WO2004076600A1 - Method for producing liquefied petroleum gas mainly containing propane or butane - Google Patents

Abstract

A synthesis gas containing carbon monoxide and hydrogen is produced from a carbon-containing material such as natural gas, at least one kind selected from the group consisting of H2O, O2 and CO2, and a recycled low boiling-point component which is separated from a lower paraffin-containing gas. A lower paraffin-containing gas which includes the low boiling-point component that has a boiling point or a sublimation point lower than the boiling point of propane is produced from the synthesis gas in the presence of a catalyst. The hydrocarbons contained in the lower paraffin-containing gas are mainly composed of propane or butane. An LPG mainly containing propane or butane is obtained by separating the low boiling-point component from the lower paraffin-containing gas, and the separated low boiling-point component is recycled as a material for synthesis gas production.

Description

 Specification

 Method for producing liquefied petroleum gas mainly containing propane or bush

 The present invention relates to a method for producing liquefied petroleum gas whose main component is propane or butane from synthesis gas. The present invention also relates to a method for producing a liquefied petroleum gas whose main component is propane or butane from a carbon-containing raw material such as natural gas.

'' Old style art

 Liquefied petroleum gas (LPG) is obtained by compressing petroleum or natural gas hydrocarbons that exhibit a gaseous state at normal temperature and pressure, or cooling them at the same time to make them liquid, the main component of which is propane or propane. It is. LPG, which can be stored and transported in liquid form, is highly portable and, unlike natural gas, which requires a pipeline for supply, can be supplied to any location in a packed state There is a feature. Therefore, LPG containing propane as a main component, that is, propane gas, is widely used as fuel for home and business use. At present, even in Japan, provangas is supplied to approximately 25 million households (over 50% of all households). In addition to LPG, LPG is used not only for household and commercial fuels, but also as mobile fuels (mainly butane gas) such as casset stoves, disposable lit-airs, industrial fuels, and automotive fuels.

 Conventionally, LPG has been separated from 1) a method of recovering from wet natural gas, 2) a method of recovering crude oil from a sulfurizing (vapor pressure adjustment) process, and 3) a product generated in a petroleum refining process. It is produced by such methods.

 LPG, especially propane gas, which is used as a fuel for home and business use, is expected to be demanded in the future and is very useful if a new production method that can be implemented industrially can be established.

As a method of manufacturing LPG, "Selective Synthes is of LPG rom Synt hesis Gas ", Kao ru Fuj imo toeta 1., Bull. Chem. Soc. Jpn., I_8_, p. 3059-3060 (1985) has a catalyst for methanol synthesis. there _{4wt% Pd / S i0 2,} Cu- Zn- A1 mixed Sani匕物[Cu: Zn: Al = 40 : 23: 37 ( atomic ratio) or Cu-based low-pressure methanol synthesis catalyst (trade name: BASF S 3-85), via use of a Haiburitsu anode catalyst comprising a high silica Y type zeolite i bets _{S i 0 2 / a 1 2} 0 3 = 7. 6, methanol from synthesis gas, the Jimechirue one ether C A method for producing 2- to C4 paraffins with a selectivity of 69 to 85% is disclosed, however, in this method, the content of components having 2 or less carbon atoms in the product is not low, and propane ( The selectivities of C3) and butane (C4) are around 63-74%, making the product less suitable as an LPG product.

 In addition, the above-mentioned “Se l ective Sent h s し f LPG from Synt he s is Gas”, Bul l. Chem.

Jpn., 58. p. 3059-3060 (1985). The main component of the product obtained is butane. LPG used as fuel for domestic and commercial use is propane gas as mentioned above. Propane gas has the advantage that it can continue burning at a stable and high output even at low temperatures, compared to butane gas. Household • Easy-to-liquefy fuel gas, which is widely used as a commercial fuel, industrial fuel, and automotive fuel, has a higher vapor pressure, sufficient in winter or cold regions, and is suitable for combustion. In comparison, propane gas, which is the highest in calories, is superior to butane gas. Disclosure of date

An object of the present invention is to produce propane and / or pulp from synthesis gas with high selectivity, to produce LPG having a low concentration of components having 2 or less carbon atoms and a high concentration of propane and / or butane. To provide a way to do it. Furthermore, An object of the present invention is to provide a method for producing LPG having a low concentration of components having 2 or less carbon atoms and a high concentration of propane and / or butane from a synthesis gas more economically.

 Another object of the present invention is to provide a method capable of producing LPG having a low concentration of components having 2 or less carbon atoms and a high concentration of propane and / or butane from a carbon-containing raw material such as natural gas. is there. Furthermore, by providing a more economical method for producing LPG with low concentrations of components with 2 or less carbon atoms and high concentrations of propane and Z or butane from carbon-containing raw materials such as natural gas. is there. According to the present invention, (i) a low-boiling component which is a substance having a boiling point or a sublimation point lower than that of propane from a synthesis gas in the presence of a catalyst, and the main component of the contained hydrocarbon is propane or butane A lower paraffin production process for producing a lower paraffin-containing gas,

 (ii) a step of separating the low-boiling component from the lower paraffin-containing gas to obtain a liquefied petroleum gas containing propane or propylene as a main component;

Provided is a method for producing a liquefied petroleum gas containing propane or butane as a main component (the method for producing the 1-1_1 LPG).

Further, according to the present invention, it is separated from (i) a carbon-containing starting material, H ₂ 0, 0 at least a one selected from ₂ and C 0 ₂ Tona Ru group, lower-paraffin-containing gas in the separation step, A synthesis gas production process for producing synthesis gas from low-boiling components recycled as a raw material of the synthesis gas production process in the recycling process;

 (iii) in the presence of a catalyst, from the synthesis gas, a low boiling point component containing a low boiling component that is a substance having a boiling point or a sublimation point lower than the boiling point of propane, and the main component of the contained hydrocarbon is propane or butane; '' Low-paraffin production process for producing raffin-containing gas,

(iii) a step of separating the low-boiling component from the lower paraffin-containing gas to obtain a liquefied petroleum gas containing propane or butane as a main component, (iv) a recycling process for recycling the separated low-boiling components as a raw material for the synthesis gas production process.

A method for producing a liquefied petroleum gas containing propane or pulp as a main component (a method for producing LPG of 1-2) is provided.

Further, according to the present invention, (i) propane is produced from a synthesis gas containing carbon monoxide and hydrogen at a CO: H ₂ = 1: 0.5 to 1: 1.4 (molar ratio) in the presence of a catalyst. A lower-paraffin-producing process for producing a lower-paraffin-containing gas containing a low-boiling component that is a substance having a boiling point or a sublimation point lower than the boiling point of, and the main component of the contained hydrocarbon is propane or butane.

 (ii) a separation step of separating the low-boiling component from the lower paraffin-containing gas obtained in the lower paraffin production step to obtain a liquefied petroleum gas mainly containing propane or butane;

Provided is a method for producing a liquefied petroleum gas containing propane or butane as a main component (a method for producing the 2_1st LPG).

Further, according to the present invention, (i) a carbon-containing raw material and a low-boiling component separated from a lower paraffin-containing gas in a separation step and recycled as a raw material in a synthesis gas production step in a recycling step, A synthesis gas production process for producing a synthesis gas containing carbon oxide and hydrogen in a ratio of CO: H ₂ = 1: 0.5 to 1: 1.4 (molar ratio);

 (ii) The synthesis gas obtained in the synthesis gas production process in the presence of a catalyst contains low-boiling components that are substances having a boiling point or sublimation point lower than the boiling point of propane, and the main component of the contained hydrocarbon is propane. Or a lower paraffin production process for producing a lower noraffin-containing gas that is butane;

 (iii) a separation step of separating the low-boiling component from the lower paraffin-containing gas obtained in the lower paraffin production step to obtain a liquefied petroleum gas mainly containing propane or butane;

(iv) recycling the low-boiling components separated from the lower paraffin-containing gas in the separation process as a raw material in the synthesis gas production process; The present invention provides a method for producing a liquefied petroleum gas containing propane or butane as a main component (the second method for producing LPG).

 Further, according to the present invention, there is provided the above-described method for producing a liquefied petroleum gas, wherein the content of the recycled low-boiling component in the raw material is 40 to 75 mol% in the synthesis gas production process. .

 According to the present invention, the liquefied petroleum according to the above, wherein the content of low-boiling components (excluding hydrogen) in the lower-paraffin-containing gas produced in the lower-paraffin production step is 60% or less on a carbon basis. A method for producing a gas is provided.

 Further, according to the present invention, there is provided the above-described method for producing a liquefied petroleum gas, wherein the low-boiling component is at least one selected from the group consisting of ethane, ethylene and methane.

 Here, the synthesis gas refers to a mixed gas containing hydrogen and carbon monoxide, and is not limited to a mixed gas composed of hydrogen and carbon monoxide. The synthesis gas may be, for example, a mixed gas containing carbon dioxide, water, methane, ethane, ethylene and the like. The synthesis gas obtained by reforming natural gas usually contains carbon dioxide and water vapor in addition to hydrogen and carbon monoxide. Further, the synthesis gas may be a coal gas obtained by coal gasification or a water gas produced from coal coke. According to the present invention, propane and / or butane can be produced from carbon-containing raw materials such as natural gas or synthesis gas with high selectivity. That is, liquefied petroleum gas (LPG) having a low concentration of components having 2 or less carbon atoms and a high concentration of propane and / or butane can be produced from a carbon-containing raw material such as natural gas or a synthesis gas.

According to the present invention, for example, an LPG having a total content of propane and butane of 90 mol% or more, and more preferably 95 mol% or more (including 100 mol%) can be produced. Further, according to the present invention, for example, it is possible to produce LPG having a propane content of 50 mol% or more, and more preferably 60 mol% or more (including 100 mol%). Can be.

 Further, according to the 2-1 LPG production method and the 2-2 LPG production method of the present invention, the concentration of the component having 2 or less carbon atoms from the carbon-containing raw material such as natural gas or the synthesis gas is reduced. LPG, which has a lower concentration of propane and / or butane, can be produced more economically.

 —When producing liquefied fossil oil gas containing propane or butane as a main component by reacting carbon oxide and hydrogen, first, methanol is synthesized from carbon monoxide and hydrogen according to the following formula (1). Then, according to the following formula (2), carbene (H 2 C :) is generated by dehydration of methanol, and lower olefins are generated by polymerization of the carbene, and the generated lower olefins are hydrogenated to form lower paraffins (H 2 C:). LPG).

CO + 2H ₂ → CH ₃ OH (1)

Conventionally, in Fischer's Tropsch synthesis (FT synthesis) and methanol synthesis, carbon monoxide and hydrogen are used as raw material gases containing CO: H ₂ = 1: 1.8 to 1: _2.5 (molar ratio). Gas is often used. When liquefied petroleum gas is produced using a synthesis gas having such a composition as a raw material, the lower paraffin-containing gas produced from the synthesis gas is a low-boiling component having a boiling point or a sublimation point lower than the boiling point of propane, specifically, Contains relatively high amounts of unreacted raw materials, hydrogen and carbon monoxide, and by-products such as carbon dioxide, ethane, ethylene and methane. Such low-boiling components can be separated from the lower paraffin-containing gas and recycled as a raw material. However, if the amount of low-boiling components contained in the produced lower-paraffin-containing gas increases, the amount of recycle increases, which tends to lower the economic efficiency.

On the other hand, in the present invention, carbon monoxide and hydrogen are converted to CO: E ₂ = 1: 0.5 to 1: The synthesis gas containing 1.4 (molar ratio) is used as a raw material. This makes it possible to reduce the amount of low-boiling components contained in the lower-paraffin-containing gas to be produced, thereby reducing the amount of low-boiling components to be recycled as a raw material and making LPG more economical. Can be.

 The reason why LPG can be produced more economically by setting the composition of the synthesis gas as a raw material in the above range is considered as follows.

As represented by the following formula (3), in terms of stoichiometry for producing propane, the composition of the synthesis gas is preferably H ₂ / CO (molar ratio) = 7/3 = 2.33. Further, as represented by the following formula (4), in terms of the stoichiometry for producing the bush, the composition of the synthesis gas is preferably H ₂ / C 0 (molar ratio) = 9/4 = 2.25. On the other hand, in the conversion reaction from synthesis gas to LPG, water is by-produced as shown in the following equations (3) and (4). This by-produced water is considered to react with carbon monoxide to generate hydrogen as shown in the following equation (5).

3CO + 7H ₂ → C ₃ H ₈ + 3H ₂ 0 (3)

4CO + 9H ₂ → C4H10 + 4H ₂ 0 (4)

CO + H ₂ 0 → C 0 ₂ + H ₂ (5) By setting the composition of the synthesis gas as a raw material within the above range, the reaction represented by the above formula (5) proceeds, and carbon monoxide decreases. By increasing the amount of hydrogen, an optimal feed gas composition for the synthesis of LPG (pan and / or butane) is obtained, and as a result, the content of low-boiling components in the lower-paraffin-containing gas produced is reduced. It is considered to be. Simple PHP 昍 FIG. 1 is a process flow diagram showing a main configuration of an example of an LPG manufacturing apparatus suitable for carrying out the present invention.

 Explanation of major signs

 1 Reformer

 1 a Reforming catalyst (Syngas production catalyst)

 汉 instrument

 2a Catalyst for lower paraffin production

 3 Separator

 11, 12, 13, 14, 15 lines

 16 Recycling line

 Ί¾ of 开

 [Syngas production process]

In the synthesis gas production step, a carbon-containing starting material, Eta ₂ 〇, 0 at least a one is ₂ and selected Ri by the group consisting of CO _2, and low-boiling component separated from the lower-paraffin-containing gas in the step of separating later To produce a synthesis gas containing preferably carbon monoxide and hydrogen at a CO: H ₂ ratio of 1: 0.5 to 1: 1.4 (molar ratio). Low boiling components are substances that have a boiling point or sublimation point lower than that of propane.

The carbon-containing material, a substance containing carbon, can be used for H ₂ 0, 0 can generate ₂ and reacted with at least one selected from the group consisting of C0 ₂ H ₂ and CO . As the carbon-containing raw material, those known as raw materials for synthesis gas can be used. For example, lower hydrocarbons such as methyl ethane and the like, natural gas, naphtha, coal and the like can be used.

In the present invention, since a catalyst is usually used in the synthesis gas production process and the lower paraffin production process, the content of catalyst poisoning substances such as sulfur and sulfur compounds as carbon-containing raw materials (natural gas, naphtha, coal, etc.) is reduced. Less is preferred. If the carbon-containing raw material contains a catalyst poisoning substance, if necessary, Prior to this, a step of removing catalyst poisoning substances such as desulfurization can be performed.

Synthesis gas in the presence of synthesis gas production catalyst (reforming catalyst), and carbon-containing starting material as described above, and at least one selected from the group consisting of H ₂ 0, 0 ₂ and C 0 ₂ It is produced by reacting. The synthesis gas can be produced by a known method. For example, when natural gas (methane) is used as a raw material, synthesis gas can be produced by a steam reforming method, an autothermal reforming method, or the like. In this case, steam necessary for steam reforming, oxygen necessary for autothermal reforming, and the like can be supplied as needed. When coal is used as a raw material, synthesis gas can be produced using an air-blown gasifier. When producing a synthesis gas containing carbon monoxide and hydrogen in a CO: H ₂ = 1: 0.5 to 1: 1.4 (molar ratio), for example, natural gas (methane) and carbon dioxide are produced. 1: due 1 a method of reacting with (molar ratio) degree (C_〇 ₂ reforming), can be produced synthesis gas composition as described above. Among them, in the present invention, it is preferable to produce a synthetic gas by automatic thermal reforming.

In the present invention, in view of economic efficiency, and carbon-containing starting material as described above, together with at least one selected from the group consisting of H ₂ 0, 0 ₂ and co _2, lower Barafin containing in the separation degree E below It is also preferable to use low-boiling components separated from the gas as raw materials in the synthesis gas production process.

Low boiling components include hydrogen, carbon monoxide, carbon dioxide, ethane, ethylene, methane, and the like. Of these, methane, ethylene and ethylene are carbon-containing raw materials. Also, carbon dioxide, for example, can be returned to by connexion syngas C 0 ₂ Rifo gang ing reaction represented by the following formula (6). By recycling low-boiling components as raw materials in the synthesis gas production process, it is possible to reduce the raw material unit consumption.

CH ₄ + C0 ₂ 2H ₂ + 2CO (6) The content of low-boiling components in the raw material, that is, the content of recycled raw material is determined as appropriate For example, it can be 40 to 75 mol%. From the viewpoint of economy and the like, the content of the low boiling component in the raw material is more preferably 55 mol% or less.

 Then, in this synthesis gas production step, synthesis gas is produced from the above-mentioned raw materials.

Further, for example, the shift reactor provided downstream of the reformer, which is a reactor for producing synthesis gas from a raw material as described above, the shift reaction _{(CO + H 2 0 C0 2} + H 2) Niyotsu Te Synthesis The composition of the gas can also be adjusted.

In the present invention, the preferred composition of the synthesis gas produced from the synthesis gas production process is as follows: in terms of stoichiometry for producing lower paraffins, the molar ratio of H ₂ / CO is 7/3 = 2.3, The content ratio (on a molar basis) of hydrogen to carbon monoxide in the produced synthesis gas can be 1.5 to 3 [H ₂ / CO]. Since hydrogen is generated by the shift reaction with water generated in the conversion reaction from synthesis gas to LPG, the content ratio of hydrogen to carbon monoxide in the synthesis gas is determined from the viewpoint that carbon monoxide is suitably reacted.

(Mole _{basis), 1. 5 [H 2 / CO} ] or _{preferably, 1. 8 [H 2 / CO} ] on than is more preferable. In addition, hydrogen only needs to have an amount capable of suitably reacting with carbon monoxide and obtaining a liquefied petroleum gas whose main component is propane or butane.Excess hydrogen requires unnecessary total pressure of the raw material gas. Raising it reduces the economics of the technology. From this point, the content ratio (on a molar basis) of hydrogen to carbon monoxide in the synthesis gas is preferably 3 [Η, / CO] or less, more preferably 2.3 [H ₂ / CO] or less.

 In order to produce a synthesis gas having the above composition, the feed ratio of the carbon-containing raw material to steam (water), oxygen, and carbon dioxide, the content of low-boiling components in the raw material, and the synthesis gas production catalyst used And the operating conditions for the reaction may be appropriately selected.

For example, as the raw material gas, use a gas with a composition such that steam / methane (molar ratio) is 1 and carbon dioxide / methane (molar ratio) is 0.4, and 1 ^ 11% is 1111 / sintered. Reaction temperature (catalyst layer outlet temperature) 800 ~ 900 ° C, reaction pressure l ~ 4MPa, gas space velocity (GHSV) 200 in an externally heated multi-tube reaction tube type device filled with magnesia catalyst for reducing surface area Syngas can be produced under operating conditions such as Ohr- ¹ You.

When reforming using steam in syngas production, the ratio of steam to raw carbon (S / C) is preferably 1.5 or less from the viewpoint of energy efficiency. .2 is more preferable. On the other hand, if the S / C is set to such a low value, the possibility of carbon precipitation cannot be ignored. On the other hand, when the low-boiling components obtained in the separation process are recycled to the synthesis gas production process, not only methane contained in this component, but also ethylene and ethylene become carbon-containing raw materials. is, it is possible to even carbon dioxide generated by the shift reaction returned to by connexion syngas C 0 ₂ riffs Omingu reaction can either be reduced raw material consumption rate, and, as described above the S / C Even at very low values, the likelihood of carbon deposition occurring can be reduced by the co ₂ reforming reaction.

 In the case of performing the above-mentioned recycling and producing the synthesis gas at a low S / C, for example, refer to WO 98/46524, JP-A-2000-288394, or JP-A-2000-469. It is preferable to use a catalyst having good syngasification reaction activity, as described, but with reduced carbon deposition activity. Hereinafter, these catalysts will be described.

The catalyst described in WO 98/46524 is a catalyst in which at least one catalyst metal selected from rhodium, ruthenium, iridium, palladium and platinum is supported on a support made of a metal oxide. The specific surface area of the catalyst is 25 m ² / g or less, the electronegativity of metal ions in the carrier metal oxide is 13.0 or less, and the amount of the catalyst metal carried is a carrier in terms of metal. The catalyst is 0.0005 to 0.1 mol% based on the metal oxide. From the viewpoint of preventing carbon deposition, the degree of electric anisotropy is preferably from 4 to 12, and the specific surface area of the catalyst is preferably from 0.01 to 10 m ² Zg.

 The electronegativity of the metal ions in the metal oxide is defined by the following equation.

Xi = (1 + 2 i) Xo Here, Xi is the electronegativity of the metal ion, Xo is the electronegativity of the metal, and i is the number of valence electrons of the metal ion.

 If the metal oxide is a composite metal oxide, the average metal ion electronegativity is used, and the value is calculated based on the electronegativity of each metal ion contained in the composite metal oxide. The sum of the values multiplied by the mole fraction of the sword.

 The electronegativity (Xo) of metals is based on Pauling's electronegativity. Pauling's electronegativity uses the values listed in Table 15.4 of "Ryo Fujishiro, Moore Physical Chemistry (2) (4th edition), Tokyo Kagaku Dojin, p. 707 (1974)". The electronegativity (Xi) of metal ions in metal oxides is described in detail in, for example, “Catalysis Society of Japan, Catalyst Course, Vol. 2, p. 145 (1985)”.

 In this catalyst, examples of the metal oxide include metal oxides containing one or more metals such as Mg, Ca, Ba, Zn, AlZr, and La. An example of such a metal oxide is magnesia (MO).

 In the case of a method in which methane reacts with steam (steam reforming), the reaction is represented by the following equation (7).

_{CH 4 + H 2 0 3H 2} + CO (7) when the method of reacting methane and carbon dioxide (C_〇 ₂ Rifo one timing), the reaction is represented by the following formula (8).

For _{CH 4 + C0 2 2H 2 +} 2CO (8) a method of reacting methane with steam and carbon dioxide (steam / C_〇 ₂ mixed riffs O one timing), the reaction is represented by the following formula (9).

3CH ₄ + 2H ₂ 0 + C0 ₂ 8H ₂ + 4CO (9) When performing steam reforming using the above catalyst, the reaction temperature is preferably 600 to 1200 ° C, more preferably 600 to 1000 ° C, and the reaction pressure is preferably 0.098 MPa aG. ~ 3.9MPaG, more preferably 0.49MPaG ~ 2.9MPaG (G indicates gauge pressure). When the steam reforming is performed by the fixed bed method, the gas space velocity

(GHS V) is preferably from 1,000 to 10,000, and more preferably from 2,000 to 8,000 Ohr ¹ . The ratio of the use of steam to the carbon-containing raw material is as follows: 1 mol of carbon in the carbon-containing raw material (including the recycled raw material, excluding C〇2), preferably 0.5 to ₂ mol of steam (H ₂₀ ). The ratio is more preferably 0.5 to 1.5 mol, and even more preferably 0.8 to 1.2 mol.

When performing C 0 ₂ Rifo one timing using the above catalyst, the reaction temperature is preferably rather is 500 ~ 1200 ° C, more preferably from 600 to 1000 ° C, the reaction pressure is preferably 0 49 MPaG to 3.9MPaG ヽ More preferably, it is 0.49MPaG to 2.9MPaG. Also, when performing the C 0 ₂ reforming a fixed bed scheme, the gas space velocity (GHSV) preferably 000~ 1 0 ₃ 000 hr ~ \ more preferably 2, 000~8, 00 Oh r ¹ It is. A rate of C 0 ₂ for carbonaceous MotoHara charges, including carbon-containing starting material (recycle material,

C_〇 except ₂₎ carbon per mole in a proportion of preferably C_〇 ₂ from 20 to 0.5 mol, and more favorable Mashiku 10-1 mol.

Using the above catalyst, by reacting a mixture of steam and C 0 ₂ in a carbon-containing starting material for producing a synthesis gas (performing steam / co ₂ mixed Rifo one timing), the mixing of the steam and C0 ₂ the proportion is not particularly limited, in general, H ₂ 0 / C_〇 ₂ (molar ratio) is 0. 1 to a 10, the reaction temperature is preferably 5 50~ 1 200 ° C, more preferably Is from 600 to 1,000 ° C., and the reaction pressure is preferably from 0.29 MPa aG to 3.9 MPa, more preferably from 0.49 MPa aG to 2.9 MPa aG. When this reaction is carried out in a fixed bed system, its gas space velocity (GHS V) is preferably 1,000 to; L◦, 00 Ohr, more preferably 2,000 to 8, OO Ohr ¹ . A rate of steam to carbon-containing starting material, (including recycle material, C0 ₂ except) a carbon-containing starting material carbon per mole in, rather preferably the steam (H ₂ 0) 0. 5 to 2 mol, The ratio is more preferably 0.5 to: 0.5 mol, and further preferably 0.5 to 1.2 mol.

The catalyst described in JP-A-2000-288394 is composed of a composite oxide having a composition represented by the following formula (I), and M ¹ and Co are highly dispersed in the composite oxide. It is a catalyst characterized by the above.

^{a 1 M 1 · b 1 C} 0 · c 'Mg · d x Ca ■ e x O (I)

^{(Wherein, a. 1, b 1,} c 1, d 1, e 1 is the mole ^{fraction, a 1 + b 1 + c} 1 + d 1 = 1, 0. 0001 ^ a ^ O. 10, 0. 0001≤b ^! ≤0.20,

0.70≤ (c ^ d ¹ ) ≤ 0.9998, 0 <c ^! ≤ 0.99998,

0≤ά '<0.9998, and e ¹ is the number necessary for the element to keep charge balance with oxygen.

M ¹ is at ^{least one} of Group 6A elements, Group 7A elements, Group 8 transition elements except Co, Group IB elements, Group 2B elements, Group 4B elements, and Lanthanoid elements. Is also one type of element. )

The catalyst described in JP-A-2000-469 is composed of a composite oxide having a composition represented by the following formula (II), and M ² and Ni are highly dispersed in the composite oxide. A catalyst characterized in that:

a ² M ² -b ² Ni-c ² Mgd ² Cae ²⁰ (II)

(Where a ² , b ² , c ² , d ² , and e ² are mole fractions, a ² + b ² + c ² + d ² = 1 ヽ 0. 0001≤a ² ≤0.10, 0.0001≤b ² ≤0.10,

0.80≤ (c ² + d ² ) ≤ 0.9998, 0 <c ² ≤ 0.99998,

0≤d ² <0.9998, and e ² is the number required for the element to be in charge balance with oxygen.

M ² is a group 3B element, a group 4A element, a group 6B element, or a group 7B element of the periodic table. Element, at least one element of Group 1A element and lanthanide element. These catalysts can be used in the same manner as the catalyst described in WO98 / 46524.

From the viewpoint of economy, in a more preferred 2-2 method for producing LPG, in this synthesis gas production process, carbon monoxide and hydrogen are converted from CO: H ₂ = 1: 0.5 to 1: 1.4 (molar ratio). Manufacturing is the ratio of hydrogen to carbon monoxide in the synthesis gas (molar _{basis), 0. 55 [H 2 / CO} ] or _{preferably, 0. 6 [H 2 / CO} ] above is more preferable. A ratio (molar basis) of hydrogen to carbon monoxide in the synthesis gas produced is: 1. preferably ₂ [H 2 / CO] Hereinafter, 1. favored more is 1 [H ₂ / CO] or less correct .

 By setting the composition of the synthesis gas within the above range, as described above, the amount of low boiling components contained in the lower paraffin-containing gas obtained in the next lower paraffin production process is reduced, and as a result, the low boiling components are converted into raw materials. As a result, the amount to be recycled is reduced, and LPG can be produced more economically.

Further, for example, the shift reactor provided downstream of the reformer, which is a reactor for producing synthesis gas from a raw material as described above, synthetic Te shift reaction _{(CO + H 2 0 → C0} 2 + H) Niyotsu The composition of the gas can be adjusted to the above range.

 In order to produce a synthesis gas having a composition within the above range, the supply ratio of the carbon-containing raw material to at least one selected from the group consisting of water, oxygen and carbon dioxide, the content of the low-boiling component in the raw material The type of the synthesis gas production catalyst to be used and other reaction conditions may be appropriately selected.

The synthesis gas containing CO and H ₂ = l: 0.5 to 1: 1.4 (molar ratio) containing carbon monoxide and hydrogen used as a raw material of the lower paraffin-containing gas in the present invention is, for example, as follows: It can be manufactured by such a method.

In the presence of a reforming catalyst comprising a composite oxide having a composition represented by the following formula (III), a carbon-containing raw material (a carbon-containing raw material in a low-boiling component separated from a lower paraffin-containing gas) ), Oxygen, carbon dioxide, and steam (steam) in the raw material gas introduced into the reactor with a (carbon dioxide + steam) / carbon ratio of 0.5 to 3, and an oxygen / force-carbon ratio of 0.5. By performing the reaction at a temperature of 900 to 1100 ° C. and a pressure of 5 to 60 kg / cm ² at the reactor outlet, the synthetic gas used in the present invention can be produced.

 aM- bCo-cNi-dMg-eCa-f O (III)

 (Where M is a Group 6A element, a Group 7A element, a Group 8 transfer element other than Co and Ni, a Group 1B element, a Group 2B element, a Group 4B element and a Represents at least one element selected from the group consisting of node elements, a, b, c, d and e represent the atomic ratio of each element, and when a + b + c + d + e = l , 0≤a≤0.1, 0.01≤ (b + c) ≤0.3, 0≤b≤0.3, 0≤c≤0.3, 0.6≤ (d + e) ≤ 0.999, 0 <d ≤ 0.999, 0 ≤ e ≤ 0.999, and f is the number required for each element to maintain charge balance with oxygen.)

The ratio of (carbon dioxide + steam) / carbon in the raw material gas introduced into the reactor is preferably about 0.5 to 2. The temperature at the outlet of the reactor is preferably 950 to 1050 ° C. The pressure at the outlet of the reactor is preferably 15 to 20 kg / cm ² .

The space velocity of the raw material gas is usually 500~200000hr- ^1, 1000 -100000 hr one ¹ are preferred, 1000 to 70000 hr one ¹ is more preferred. In the composite oxide having the composition represented by the above formula (III), MgO ヽ CaO has a rock salt type crystal structure, and some of the Mg or Ca atoms located in the lattice are replaced with Co, Ni or M. It is a kind of solid solution that forms a single phase.

 In the above formula (III), M may be at least one element selected from the group consisting of manganese, molybdenum, rhodium, ruthenium, platinum, palladium, copper, silver, zinc, tin, lead, lanthanum and cerium. preferable.

The content (a) of M is 0≤a 0.1, preferably 0≤.a≤0.05, and more preferably 0≤a≤0.03. If the M content (a) exceeds 0.1, the activity of the reforming reaction decreases. The cobalt content (b) is 0≤b≤0.3, preferably O ^ b ^ O.25, and more preferably 0≤b≤0.2. If the content of the cobalt (b) exceeds 0.3, it is difficult to sufficiently obtain the effect of preventing carbonaceous deposition.

 The nickel content (c) is 0≤c≤0.3, preferably 0≤c ^ 0.25, and more preferably 0≤c≤0.2. If the nickel content (c) exceeds 0.3, it is difficult to sufficiently obtain the effect of preventing carbonaceous deposition.

 The total (b + c) of the cobalt content (b) and the nickel content (c) is 0.001≤ (b + c) ≤ 0.3, and 0.001≤ (b + c) ≤ 0.25, more preferably 0.001 ≤ (b + c) ≤ 0.2. When the total content (b + c) exceeds 0.3, it is difficult to sufficiently obtain the effect of preventing carbonaceous deposition. On the other hand, when the total content (b + c) is less than 0.001, the reaction activity decreases.

 The sum of magnesium content (d) and calcium content (e) (d + e) is 0.6 ≤ (d + e) ≤ 0.9998, and 0.7 ≤ (d + e) ≤ 0 9998, and more preferably 0.9. (D + e) ≦ 0.9998.

 Of these, the magnesium content (d) is 0 <d≤ 0.999,

d ≦ 0.9998 is preferable, and 0.37 ≦ d ≦ 0.9998 is more preferable. Further, the calcium content (e) is 0≤e <0.999, preferably 0≤e≤0.5, and more preferably 0≤e≤0.3. The catalyst may not contain calcium.

The total amount of magnesium content (d) and calcium content (e) (d + e) is determined by balancing M content (a), cobalt content (b) and nickel content (c). Can be (D + e) exhibits an excellent effect on the reforming reaction at any ratio as long as it is within the above range. However, if the content of calcium (e) and M (a) is large, it is high in suppressing carbonaceous deposition. Although effective, the catalytic activity tends to be lower than when magnesium (d) is high. In terms of activity, calcium content (e) is preferably 0.5 or less, and the M content (a) is preferably 0.1 or less. The reforming catalyst used preferably has at least one of M, Co and Ni highly dispersed in the composite oxide. Here, the dispersion is defined as the ratio of the number of atoms exposed on the catalyst surface to the total number of atoms of the supported metal. That is, if the number of atoms of the Co, Ni or M metal element or its compound is A, and the number of these atoms exposed on the particle surface is B, BZA becomes the dispersion. By using a reforming catalyst in which at least one of M, Co and Ni is highly dispersed in the composite oxide, the reaction becomes more active and the reaction proceeds stoichiometrically. ) Is more effectively prevented.

 Examples of a method for producing such a reforming catalyst include an impregnation-supporting method, a coprecipitation method, a sol-gel method (hydrolysis method), and a uniform precipitation method.

 The above-mentioned reforming catalyst is usually subjected to an activation treatment before it is used for syngas production. The activation treatment is performed in the presence of a reducing gas such as hydrogen gas at a temperature of 500 to 1000 ° C, preferably 600 to 1000 ° C, more preferably 650 to 0.5 to 30 ° C in a temperature range of L000 ° C. This is done by heating the catalyst for about an hour. The reducing gas may be diluted with an inert gas such as nitrogen gas. This activation treatment can also be performed in a reactor that performs a reforming reaction. By this activation treatment, catalytic activity is developed.

Another method of producing the synthesis gas used in the present invention is to partially oxidize a carbon-containing raw material (including a carbon-containing raw material in a low-boiling component separated from a lower paraffin-containing gas) to obtain unreacted carbon-containing material. A mixed gas containing a raw material and having a temperature of at least 600 ° C. is generated. Supporting at least one metal (catalyst metal) selected from the group consisting of rhodium, ruthenium, iridium, palladium and platinum on an oxide support, specific surface area of 25 m ² / g or less, supporting catalyst metal Under a pressurized condition, carbon dioxide gas and / or steam was added in the presence of a catalyst in an amount of 0.0005 to 0.1 mol% based on the carrier metal oxide in terms of metal. A method of producing a synthesis gas by reacting is exemplified. In addition, a mixed gas comprising a carbon-containing raw material (including a carbon-containing raw material in low-boiling components separated from a lower-paraffin-containing gas), an oxygen-containing gas (air, oxygen, etc.), and carbon dioxide gas and / or steam. A metal oxide having a metal ion electronegativity of 13 or less, carrying at least one metal (catalytic metal) selected from the group consisting of rhodium, ruthenium, iridium, palladium and platinum. The mixing was carried out in the presence of a catalyst having a specific surface area of 25 m ² / g or less and a supporting amount of catalyst metal of 0.0005 to 0.1 mol% in terms of metal relative to the supporting metal oxide. The carbon-containing raw material in the gas is partially oxidized to generate a mixed gas containing unreacted carbon-containing raw material and having a temperature of at least 600 ° C. With carbon dioxide And / or reacting steam to produce synthesis gas.

 Here, the catalyst metal may be supported in a metal state, or may be supported in a state of a metal compound such as an oxide. Further, the metal oxide used as the carrier may be a single metal oxide or a composite metal oxide.

 The electronegativity of the metal ions in the metal oxide for a carrier is 13 or less, preferably 12 or less, more preferably 10 or less. When the electronegativity of the metal ions in the metal oxide exceeds 13, carbon deposition becomes remarkable when the catalyst is used. The lower limit of the electronegativity of metal ions in the metal oxide for a carrier is usually about 4. The electronegativity of metal ions in the metal oxide is defined by the following equation.

 X i = (1 + 2 i) X o

 X i: electronegativity of metal ion,

 X o: electronegativity of metal,

 i: the number of valence electrons of the metal ion.

When the metal oxide is a composite metal oxide, the average metal ion electronegativity is used, and the value is calculated based on the electronegativity of each metal ion contained in the composite metal oxide. The sum of the values obtained by multiplying the acid fraction by the mole fraction is used. The electronegativity (Xo) of a metal uses the electronegativity of Pau1ing. The electronegativity of Pauling is described in Table 15.4 of "Ryo Fujishiro, Moore Physical Chemistry (2) (4th edition), Tokyo Kagaku Dojin, p. 707 (1974)". The electronegativity (Xi) of metal ions in metal oxides is described in detail in, for example, “Catalysis Society of Japan, Catalyst Course, Vol. 2, p. 145 (1985)”.

Examples of such a metal oxide include metal oxides containing one or more metals such as Mg, Ca, Ba, Zn, Al, Zr, and La. As such a metal oxide, specifically, magnesia (MgO), calcium oxide (CaO), barium oxide (B aO-), zinc oxide (ZnO), alumina (Al ₂ 〇 _3), Jirukonia (Z r 0 _2), and single metal oxides such as lanthanum oxide _{(L a 2 0 3),} MgO / CaO, Mg 〇 / B aO, MgO / ZnO, MgO / a 1 2 0 3, MgO / Z r 0 2, C aO / BaO, C aO / Z nO, C a O / A 1 ₂ 0 ₃ヽ C aO / Z r 0 ₂ , B a O / Z n 〇, BaO / Al ₂ 0 _3N B aO / Z r0 ₂ , _{ZnO / Al 2 0 3, Z} nO / Z r 0 2, A 1 2 0 3 / Z r 0 2N L a 2 0 3 / MgOヽ _{L a 2 0 3 / A 1} 2 0 3, L a 2 0 3 / C a 0 and the like.

Used specific surface area of the catalyst is at 25 m ² Zg less, preferably 20 m ² / g or less, more preferably 1 5 m ² / g, particularly preferably 1 Om ² / g or less. The lower limit of the specific surface area of the catalyst used is usually about 0.0 lm ² / g. By setting the specific surface area of the catalyst in the above range, the carbon deposition activity of the catalyst can be more sufficiently suppressed.

In the catalyst used here, the specific surface area of the catalyst and the specific surface area of the metal oxide as a support are substantially the same. Therefore, the specific surface area of the metal oxide as a carrier is 25 m ² / g or less, preferably 20 m ² / g or less, more preferably 15 m ² / g or less, and particularly preferably 10 m ² / g or less. The lower limit of the specific surface area of the metal oxide as a carrier is usually about 0.01 m ² / g.

Here, the specific surface area of the metal oxide as the catalyst or the carrier was measured at a temperature of 15 ° C. by the BET method. For catalysts with a specific surface area of 25 m ² / g or less, 300 to 1300 metal oxides are used as carriers before the catalyst metal is supported. Preferably, it is obtained by calcining at 650 to 1200 ° C, and after carrying the catalyst metal, calcining the obtained catalyst metal support at 600 to 1300 ° C, preferably 650 to 1200 ° C. Further, after the catalyst metal is supported on the metal oxide as a carrier, the obtained catalyst metal support is fired at 600 to 1300 ° C, preferably 650 to 1200 ° C. Can be. By controlling the calcination temperature and the calcination time, the specific surface area of the resulting metal oxide, which is a catalyst or a support, can be controlled.

 The supported amount of the catalyst metal with respect to the metal oxide serving as the support is 0.0005 to 0.1 mol% in terms of metal. The amount of the catalytic metal supported on the metal oxide as a support is preferably 0.001 mol% or more, more preferably 0.002 mol% or more, in terms of metal. The amount of the catalytic metal supported on the metal oxide as the carrier is preferably 0.09 mol% or less in terms of metal.

 Since the above-mentioned catalyst has a small specific surface area of the catalyst and a very small amount of catalyst metal carried thereon, it has a sufficient syngasification activity for the carbon-containing raw material and significantly suppresses the carbon deposition activity. O

 Such a catalyst can be prepared according to a known method. As a method for producing a catalyst, for example, a metal oxide serving as a carrier is dispersed in water, a catalyst metal salt or an aqueous solution thereof is added and mixed, and then the metal oxide supporting the catalyst metal is separated from the aqueous solution. Drying, baking (impregnating method) or exhausting the metal oxide as a carrier, adding a small amount of a metal salt solution for the pore volume little by little to make the carrier surface uniformly wet, and then drying and drying. Firing method (inc ipent—wet ne ss method).

By reacting carbon-containing raw materials (including carbon-containing raw materials in low-boiling components separated from lower paraffin-containing gas) with steam (steam) and / or carbon dioxide in the presence of a catalyst as described above. The synthesis gas used in the present invention can be produced. When the method of reacting a carbon-containing starting material with carbon dioxide (Rei_0 ₂ reforming), the reaction temperature is 500~1200 ° C, 600~1000 ° C is preferred. Reaction pressure is ^{5~40kg / cm 2 G, 5~ 30} kg / cm 2 G are preferred. When performing the reaction in a fixed bed system, a gas hourly space velocity (GHSV) is 1, a ^{000~1 0, O OOhr- 1, 2} , 000~8, 000 hr * - 1 is preferred. The content of C 0 ₂ in the feed gas to be introduced into the reactor, per one mole of carbon of the carbon-containing in the raw materials, a CO ₂ 20 to 0 5 mol,. 10 to;. L mol are preferred.

In the case of a method of reacting a carbon-containing raw material with steam (steam reforming), the reaction temperature is 600 to 1200 ° C, preferably 600 to 1000 ° C. The reaction pressure is 1 to 40 kg / cm ² G, preferably 5 to 30 kg / cm ² G. When performing the reaction in a fixed bed system, the gas space velocity (GHS V) is 1, a ^{000~1 0, O OOhr- 1, 2} , 000~8, 000 hr one ¹ is preferred. The content of steam in the feed gas to be introduced into the reactor, per one mole of carbon of the carbon-containing in the raw materials, steam (H ₂ 0) is 20 to 0.5 mol, 10-1 mol are preferred, 1.5 ~ 1 mole is more preferred.

When producing steam and mixture synthesized by reacting a carbon-containing feed gas co _2, but not mixed ratio particularly limited with steam and C 0 _2, typically, H ₂ 0 / C0 ₂ (molar ratio) 0.1 to 10.

 In this synthesis gas production method, the energy required for the reforming reaction is partially oxidized (partial combustion) of the carbon-containing raw material, which is a reaction raw material for the reforming, and is generated by combustion heat generated at that time. Replenished.

Partial oxidation reaction of the carbon-containing raw material, 600~ 1500 ° C, preferably from 700 to 13 00 Temperature of ° C and 5~50 kg / cm ² G, the pressure conditions of preferably 10~40 kg / cm ² G Will be implemented. Oxygen is used as an oxidizing agent for partially oxidizing the carbon-containing raw material. As the oxygen source, an oxygen-containing gas such as air or oxygen-enriched air is used in addition to pure oxygen. The oxygen content of the raw material gas introduced into the reactor is 0.1 to 4 as the atomic ratio of oxygen to carbon (0 / C) in the carbon-containing raw material. Yes, 0.5 to 2 is preferred.

 By the partial oxidation of the carbon-containing raw material, a high-temperature mixed gas containing at least 600 ° C, preferably 700 to 1300 ° C, containing the unreacted carbon-containing raw material is obtained. By reacting carbon dioxide and / or steam with the unreacted carbon-containing raw material in this mixed gas under the above conditions, a synthesis gas can be produced. Carbon dioxide and Z or steam may be added to and mixed with the mixed gas obtained by partial oxidation of the carbon-containing raw material, or may be added and mixed in advance to the carbon-containing raw material to be subjected to the partial oxidation reaction. You may leave. In the latter case, it becomes possible to simultaneously perform the partial oxidation of the carbon-containing raw material and the reforming reaction.

 The reforming reaction of the carbon-containing raw material can be carried out in various types of reactors, but is usually preferably carried out in a fixed bed system or a fluidized bed system.

 [Low-grade paraffin production process]

 In the lower paraffin production process, in the presence of a lower paraffin production catalyst, a low-boiling component, which is a substance having a boiling point or sublimation point lower than the boiling point of propane, from the synthesis gas obtained in the above synthesis gas production process. Produces lower norafine-containing gas containing hydrocarbons as the main component of the pan or pan.

The lower-paraffin production catalyst, for example, is a catalyst for methanol synthesis 4 _{wt% Pd / S i 0 2,} Cu- Zn- A1 mixed oxide [Cu: Zn: Al = 40 : 23: 37 ( atomic ratio) ] and Cu-based low-pressure methanol synthesis catalyst (trade name: BASF S3- 85) at least the one selected _{from, S i 0 2 / a 1} 2 〇 ₃ = 7. mixed catalyst obtained by mixing the Y-type Zeorai bets 6 Can be used. The mixing ratio of the former and the latter can be, for example, about 1: 1 by mass.

 Examples of the lower paraffin-producing catalyst including the above-mentioned catalyst include, for example, a catalyst containing one or more methanol synthesis catalyst components and one or more zeolite catalyst components.

Here, the methanol synthesis catalyst component refers to a component that exhibits a catalytic action in the reaction of C〇 + 2H ₂ CH ₃ OH. In addition, the zeolite catalyst component refers to methanol Refers to zeolite that exhibits a catalytic action in the condensation reaction to hydrogen chloride and / or the condensation reaction of dimethyl ether to hydrocarbon.

 When carbon monoxide is reacted with hydrogen in the presence of the lower paraffin production catalyst, the following reaction occurs, and paraffins whose main component is propane or butane can be produced.

First, methanol is synthesized from carbon monoxide and hydrogen on the methanol synthesis catalyst component. Next, the synthesized methanol is converted into a lower olefin hydrocarbon whose main component is propylene or putene at an active site in the pores of the zeolite catalyst component. In this reaction, carbene (H ₂ C :) is generated by dehydration of the methanol, and it is considered that lower olefins are formed by polymerization of the carbene. Then, the generated lower olefins escape from the pores of the zeolite catalyst component and are rapidly hydrogenated on the methanol synthesis catalyst component to become paraffins whose main component is propane or butane.

 The content ratio (by mass) of the methanol synthesis catalyst component to the zeolite catalyst component is preferably 0.5 or more [methanol synthesis catalyst component / zeolite catalyst component], and 0.8 or more [methanol synthesis catalyst]. Catalyst component / zeolite catalyst component]. Further, the content ratio (by mass) of the methanol synthesis catalyst component to the zeolite catalyst component is preferably 3 or less [methanol synthesis catalyst component / zeolite catalyst component], and 2 or less [methanol synthesis catalyst component]. / Zeolite catalyst component]. By setting the content ratio of the methanol synthesis catalyst component to the zeolite catalyst component within the above range, propane and / or pentane can be produced with higher selectivity and higher yield.

The methanol synthesis catalyst component has a function as a methanol synthesis catalyst, and the zeolite catalyst component is a solid acid zeolite catalyst whose acidity is adjusted to the condensation reaction of methanol and / or dimethyl ether to hydrocarbons. It has the function of Therefore, the content ratio of the methanol synthesis catalyst component to the zeolite catalyst component is determined by the function of the catalyst to synthesize methanol and the function of generating hydrocarbons from methanol. It is reflected in the relative ratio. In producing paraffins whose main components are propane or butane by reacting carbon monoxide and hydrogen in the present invention, carbon monoxide and hydrogen must be sufficiently converted to methanol by a methanol synthesis catalyst component. In addition, the produced methanol is sufficiently converted to olefins whose main component is propylene or butene by the zeolite catalyst component, and the main component is converted to propane or butane by the methanol synthesis catalyst component. It must be converted to certain paraffins.

 By setting the content ratio (by mass) of the methanol synthesis catalyst component to the zeolite catalyst component to 0.5 or more [methanol synthesis catalyst component / zeolite catalyst component], higher conversion of carbon monoxide and hydrogen can be achieved. Can be converted to methanol. In addition, by setting the content ratio (mass basis) of the methanol synthesis catalyst component to the zeolite catalyst component to 0.8 or more [methanol synthesis catalyst component / zeolite catalyst component], the produced methanol can be more selectively treated with propane or methanol. It can be converted to paraffins whose main component is butane.

 On the other hand, the content ratio (by mass) of the methanol synthesis catalyst component to the zeolite catalyst component is 3 or less [methanol synthesis catalyst component / zeolite catalyst component], more preferably 2 or less [methanol synthesis catalyst component / zeolite catalyst component]. ], The produced methanol can be converted into paraffins whose main component is propane or butane at a higher conversion rate.

 Examples of the methanol synthesis catalyst component include known methanol synthesis catalysts, specifically, Cu—Zn system, Cu—Zn—Cr system, Cu—Zn—A1 system, Cu—Zn—Ag system, Cu — Zn— Mn— V system, Cu—Zn— Mn— Cr system, Cu-Zn-Mn-Al—Cr—Zn system and others with a third component added, or Ni— Examples include those based on Zn, those based on Mo, those based on Ni-carbon, and those based on noble metals such as Pd. Also, a commercially available methanol synthesis catalyst can be used.

The zeolite catalyst component has a three-dimensional expansion of pores through which reactive molecules can diffuse. A medium pore zeolite or a large pore zeolite is preferred. These include, for example, ZSM_5, MCM-22, Peter, Y-type, and the like. In the present invention, small pore zeolites such as SAPO-34 or porphyrins such as mordenite generally exhibit high selectivity for the condensation reaction of methyl and / or dimethyl ether to lower olefin hydrocarbons. ZSM-5, MCM-22, etc., which generally show higher selectivity for the condensation reaction of methanol and / or dimethyl ether to alkyl-substituted aromatic hydrocarbons than zeolite, in which the diffusion of reactive molecules in the pores is not three-dimensional. Zeolite in which the diffusion of reactive molecules in pores such as medium-pore zeolite or large-pore zeolite such as Y-type is preferred. The use of zeolite 1, which has three-dimensional diffusion of reactive molecules in pores such as medium pore zeolite and large pore zeolite, allows methane or butene to be used as a main component in order to more selectively produce the generated methanol. Olefins, or paraffins containing propane or pentane as a main component.

 Here, the medium pore zeolite refers to a zeolite having a pore diameter of 0.44 to 0.65 nm formed mainly by a 10-membered ring, and the large pore zeolite has a pore diameter of Is a zeolite of 0.66-0.76 nm formed mainly by a 12-membered ring. The pore size of the zeolite catalyst component is more preferably 0.5 nm or more from the viewpoint of the selectivity of the C3 component and the C4 component in the gaseous product. Further, the skeleton pore diameter of the zeolite catalyst component is more preferably 0.77 nm or less from the viewpoint of suppressing the production of liquid products such as aromatic compounds such as benzene and gasoline components such as C5 component.

As the Zeorai bets catalyst component, the so-called髙Shirikazeorai DOO, specifically _{S i 0 2 / A 1 2} 0 3 molar ratio Zeorai bets 1 0-5 0 preferred. By S I_〇 ₂ / A 1 ₂ 0 ₃ molar ratio is used high Shirikazeorai bets 1 0-5 0, Orefin such that the generated main component more selectively propylene or butene with methanol, more propane or It can be converted to paraffins containing butane as the main component.

The Zeorai bets catalyst component in _{S i 0 2 / Α 1 2} 0 3 molar ratio of 1 0-5 0, counter A medium pore zeolite or a large pore zeolite having three-dimensional expansion of pores through which a reactive molecule can diffuse is particularly preferable. As such, for example, a solid acid zeolite such as USY ゃ high silica type Beiyu can be mentioned.

 As the zeolite catalyst component, a solid acid zeolite as described above whose acidity is adjusted by ion exchange or the like is used.

 As the catalyst for producing lower paraffin, a mixture prepared by separately preparing a methanol synthesis catalyst component and a zeolite catalyst component and mixing them is preferable. By separately preparing the methanol synthesis catalyst component and the zeolite catalyst component, it is easy to optimally design the composition, structure, and physical properties of each function for each function.

 Some methanol synthesis catalysts need to be activated by reduction before use. In the present invention, it is not always necessary to preliminarily reduce and activate the methanol synthesis catalyst component, and the methanol synthesis catalyst component and the zeolite catalyst component are mixed and molded to form a lower paraffin production catalyst. After the production, a reduction treatment can be performed before starting the reaction to activate the methanol synthesis catalyst component. The lower paraffin-producing catalyst may contain other additional components as needed, as long as the desired effect is not impaired.

 In the lower paraffin production step, carbon monoxide is reacted with hydrogen using the above catalyst to produce paraffins whose main component is propane or butane, preferably paraffins whose main component is propane.

The gas fed into the reactor is the synthesis gas obtained in the above synthesis gas production process. In other words, in the more preferred 2-1 method for producing LPG and the 2-2 method for producing LPG from the viewpoint of economy, the gas fed into the reactor contains carbon monoxide and hydrogen. CO: H ₂ = 1: 0.5 to 1: 1.4 (molar ratio). Ratio of hydrogen to carbon monoxide in the gas fed to the reactor (mol _{basis), 0. 55 [H 2 / CO} ] or _{preferably, 0. 6 [H 2 / CO} ] on more than more preferable. A ratio of hydrogen to carbon monoxide in the gas fed to the reactor (mol basis), 1. preferably ₂ [H 2 / CO] Hereinafter, 1. 1 [H ₂ / CO] is more preferable.

 The concentration of carbon monoxide in the gas fed into the reactor is preferably at least 20 mol% from the viewpoints of securing a pressure (partial pressure) of carbon monoxide suitable for the reaction and improving the unit consumption of raw materials. , 25 mol% or more is more preferable. Further, the concentration of carbon monoxide in the gas fed into the reactor is preferably 67 mol% or less, more preferably 60 mol% or less, from the viewpoint that the conversion of carbon monoxide becomes sufficiently high. .

 Therefore, the concentration of carbon monoxide in the synthesis gas produced in the synthesis gas production process is preferably 20 mol% or more, more preferably 25 mol% or more, and preferably 67 mol% or less. 0 mol% or less is more preferable.

 In some cases, the concentration of carbon monoxide in the gas fed into the reactor is preferably 40 mol% or less, more preferably 35 mol% or less.

 The gas fed into the reactor may contain, for example, carbon dioxide, water, methane, ethane, ethylene, an inert gas, and the like, in addition to carbon monoxide and hydrogen.

 The gas fed into the reactor may be a mixture of carbon monoxide and hydrogen, which are raw materials for producing lower paraffin, and carbon dioxide. By recycling the carbon dioxide emitted from the reactor as the carbon dioxide, or by using an amount commensurate with it, the production of carbon dioxide by the shift reaction from carbon monoxide in the reactor is substantially reduced. Or reduce carbon dioxide production.

 Further, the gas fed into the reactor may contain steam.

 The reaction temperature is preferably at least 270 ° C, more preferably at least 300 ° C, from the viewpoint that the methanol synthesis catalyst component and the zeolite catalyst component exhibit sufficiently higher activities, respectively. The reaction temperature is preferably 400 ° C or lower, more preferably 380 ° C or lower, in view of the limit temperature for use of the catalyst, the regulation of equilibrium, and the ease of removing and recovering the reaction heat. .

The reaction pressure is set to 1 because the methanol synthesis catalyst component shows a sufficiently high activity. It is preferably at least MPa, more preferably at least 2 MPa. The reaction pressure is preferably 1 OMPa or less, more preferably 5 MPa or less, from the viewpoint of economy.

Gas space velocity, in terms of economic efficiency, 5 0 O ^hr-1 or more preferably, 2 0 0 0 hr one ¹ or more is more preferable. Further, the gas hourly space velocity is preferably ¹⁰⁰ Ohr-11 or less from the viewpoint that the methanol synthesis catalyst component and the zeolite catalyst component each provide a contact time showing a sufficiently high conversion. , 5 0 0 O hr one ¹ or less is not more preferable.

 The gas sent to the reactor can be split and sent to the reactor, thereby controlling the reaction temperature.

 The reaction can be carried out in a fixed bed, a fluidized bed, a moving bed or the like, but it is preferable to select from both the control of the reaction temperature and the method for regenerating the catalyst. For example, fixed beds include quench-type reactors such as internal multi-stage quench type, multi-tube type reactors, multi-stage type reactors including multiple heat exchangers, multi-stage cooling radial type single-hole type, and double-tube heat type. Other reactors such as an exchange type, a cooling coil built-in type, and a mixed flow type can be used.

 The catalyst for producing lower paraffins can be diluted with silica, alumina or the like or an inert and stable heat conductor for the purpose of controlling the temperature. In addition, the catalyst for producing lower paraffin can be used by coating it on the surface of a heat exchanger for the purpose of controlling temperature.

 In the lower paraffin-containing gas obtained in this lower paraffin production step, the main component of the contained hydrocarbon is propane or butane. From the viewpoint of liquefaction characteristics, the total content of propane and pentane in the lower paraffin-containing gas is as high as possible. In the present invention, the total content of propane and butane is 50 mol% or more, more preferably 60 mol% or more, and even 70 mol% or more (including 100 mol%) of the contained hydrocarbon. A lower paraffin-containing gas can be obtained.

Further, the lower paraffin-containing gas obtained in the lower paraffin production step preferably contains more propane than butane from the viewpoint of flammability and vapor pressure characteristics. In the present invention, the content of propane is 50 mol% or more, more preferably 55 mol% or more, and even 60 mol% or more (including 100 mol%) of lower hydrocarbons contained. Gas can be obtained.

 The lower paraffin-containing gas obtained in the lower paraffin production step contains a low-boiling component having a boiling point or a sublimation point lower than that of propane. Examples of low boiling components include by-products ethane, methane, and ethylene. Examples of the low-boiling components include carbon dioxide generated by the shift reaction, and unreacted raw materials such as hydrogen and carbon monoxide. The low boiling point component contained may be one kind or two or more kinds.

 In particular, according to the 2-1 method for producing LPG and the 2-2 method for producing LPG of the present invention, a low-paraffin-containing gas having a low content of low-boiling components can be obtained. Specifically, low-paraffin-containing gas containing 75% or less, more preferably 70% or less, and even 60% or less (excluding ◦%) of low-boiling components excluding hydrogen is based on carbon. Obtainable. In addition, a lower paraffin-containing gas having a hydrogen content of 40 mol% or less, or even 38 mol% or less (excluding 0 mol%) can be obtained.

 (Separation step)

 In the separation process, after separating water and the like as necessary from the lower paraffin-containing gas obtained in the above lower paraffin production process, low boiling components are separated, and liquefaction mainly comprising pan bread or butane Obtain oil and gas (LPG). Pressurization and / or cooling may be performed as needed to obtain liquefied petroleum gas.

 Before separating low-boiling components or after separating low-boiling components, high-boiling components that are substances with a boiling point higher than that of butane, such as high-boiling paraffin gas, are separated from lower-paraffin-containing gas. May be. Separation of the high boiling component can be carried out by a known method.

Separation of low-boiling components can be performed by a known method such as gas-liquid separation, absorption separation, or distillation. More specifically, gas-liquid separation or absorption separation at pressurized room temperature, cooling Alternatively, it can be performed by gas-liquid separation, absorption separation, or a combination thereof. Further, it can be carried out by membrane separation or adsorption separation, and can also be carried out by combining these with gas-liquid separation, absorption separation, and distillation. For the separation of low boiling components, gas recovery processes commonly used in refineries ("Petroleum Refining Process"

/ Ed., Kodansha Scientifiq, 1989, .28-p. 32) can be applied.

 As a method for separating low-boiling components, an absorption process in which a liquefied fossil oil gas containing propane or butane as a main component is absorbed by a high-boiling paraffin gas having a boiling point higher than that of butane or an absorbent such as gasoline is preferable.

 For consumer use, from the viewpoint of safety during use, it is preferable, for example, to reduce the content of low boiling components in LPG to 5 mol% or less (including 0 mol%) by separation. The total content of propane and butane in the LPG thus produced can be at least 90 mol%, and more preferably at least 95 mol% (including 100 mol%). Further, the content of propane in the LPG to be produced can be 50 mol% or more, and further, 60 mol% or more (including 100 mol%). According to the present invention, it is possible to produce LPG having a composition suitable for propane gas widely used as a fuel for home and business use.

 [Recycling process]

 In the recycling process, the low-boiling components separated from the lower paraffin-containing gas in the above separation process are recycled as raw materials for the synthesis gas production process (reforming process).

9 one.

As described above, the low-boiling components separated from the lower paraffin-containing gas include substances that can be reused as raw materials in the synthesis gas production process, such as methane, ethane, and ethylene. Furthermore, carbon dioxide contained in the low-boiling components can be returned to the synthesis gas by Rei_0 ₂ Li follower one timing reaction. Further, the low-boiling components include unreacted raw materials such as hydrogen and carbon monoxide. Therefore, the low-boiling components separated from the lower paraffin-containing gas are recycled to the synthesis gas production process. All the low-boiling components separated from the lower paraffin-containing gas may be recycled to the synthesis gas production process, or a part may be extracted out of the system and the rest may be recycled to the synthesis gas production process . Low boiling components can be recycled to the synthesis gas production process by separating only the desired components.

 In order to recycle the low-boiling components, a known technique such as appropriately providing a booster in the recycling line can be adopted.

 [Production method of LPG]

 Next, an embodiment of the method for producing LPG of the present invention will be described with reference to the drawings.

 FIG. 1 shows an example of an LPG manufacturing apparatus suitable for carrying out the LPG manufacturing method of the present invention.

 First, methane is supplied to the reformer 1 via the lines 11 and 12 as a carbon-containing raw material. Although not shown, steam is supplied to the line 12 to perform steam reforming. Further, a low-boiling component having a boiling point or a sublimation point lower than that of propane is supplied from the separator 3 to the line 12 via the recycle line 16. In the reformer 1, a reforming catalyst 1a is provided. In addition, the reformer 1 includes a heating means (not shown) for supplying heat required for reforming. In the reformer 1, methane is reformed in the presence of the reforming catalyst 1a to obtain a synthesis gas containing hydrogen, carbon monoxide, carbon dioxide, and steam.

 The synthesis gas thus obtained is supplied to the reactor 2 via the line 13. The reactor 2 is provided with a lower paraffin production catalyst 2a. In this reactor 2, a lower paraffin-containing gas containing ethane, propane and butane is synthesized from the synthesis gas in the presence of the lower paraffin production catalyst 2a.

The synthesized lower paraffin-containing gas is supplied to a separator 3 as a distillation column via a line 14. Then, a substance having a boiling point higher than the boiling point of propane, that is, LPG as a product, is obtained from the bottom of the column by pressure distillation at room temperature, and a substance having a boiling point or sublimation point lower than the boiling point of propane from the top of the column, that is, a low boiling point Components are obtained as residual gas Can be In this way, a product LPG is obtained from the line 15. On the other hand, the residual gas (low-boiling components) obtained from the top of the tower is recycled to the reformer 1 by the recycling line 16.

 Although not shown, the LPG manufacturing apparatus is provided with a booster, a heat exchanger, a valve, an instrumentation control device, and the like as necessary. Example

 Hereinafter, the present invention will be described in more detail with reference to Examples. Note that the present invention is not limited to these examples.

 (Reference Example 1)

 (Production of low-grade paraffin)

A commercially available Cu—Zn based methanol synthesis catalyst (manufactured by Nippon Suede Hemi Co., Ltd.), which was mechanically powdered, was used as the methanol synthesis catalyst component. Separately, as Zeorai preparative catalysts _{component, S i 0 2 / A 1} 2 0 3 molar ratio was prepared pro ton Z SM- 5 peptidase Orai preparative powder 14.5. Then, the methanol synthesis catalyst component and the zeolite catalyst component are uniformly mixed in the same amount on a mass basis, press-molded and sized, and then reduced in a hydrogen stream at 300 ° C for 3 hours to obtain a lower grade. A catalyst for paraffin production was obtained.

The prepared catalyst was charged into a reaction tube, and a raw material gas having a composition of 62.0 mol% of hydrogen, 31.0 mol% of carbon monoxide, 5.0 mol% of carbon dioxide, and 2.0 mol% of methane was supplied. It was distributed. The reaction conditions were as follows: reaction temperature 325 ° C, reaction pressure 2. OMP a ヽ gas space velocity 3000 hr- ¹ .

 When the product was analyzed by gas chromatography, the conversion of carbon monoxide was 71%. The conversion of carbon monoxide to carbon dioxide was 35%, and the conversion to hydrocarbons was 37%. Propane and butane accounted for 75% of the generated hydrocarbon gas on a carbon basis. Propane and butane consisted of 56% of propane and 44% of butane on a carbon basis.

(Separation and recycling of low boiling components) After gas-liquid separation of the reaction gas from the production of LPG (production of lower paraffin), the reaction gas is dried with a molecular sieve, and then methane is added to an octane solution maintained at around 0 ° C. A low-boiling gas having a composition of 7 mol%, ethylene and ethylene 1.2 mol%, carbon dioxide 21.1 mol%, unreacted carbon monoxide 12.0 mol% and hydrogen 62.0 mol%. Minutes.

 Then, the separated low boiling point component was pressurized to 2.5 MPa by a compressor and fed into the synthesis gas production process as 67 mol% of the raw material gas.

 (Syngas production)

The raw material gas having the composition of low boiling point recycled gas from the LPG production process of 67.0 mol%, natural gas of 14.7 mol%, steam of 14.8 mol%, and carbon dioxide of 3.5 mol% was obtained from WO 98 / The catalyst was prepared in advance in a stream of hydrogen in an externally heated reaction tube type apparatus filled with a Ru / sintered low surface area magnesia catalyst prepared according to Catalyst Preparation Example 9 of 46524, 900. After performing a reduction treatment with C for 1 hr, the reaction temperature is 870 ° C, the reaction pressure is 2. Reforming under the operating conditions of IMP a, GHSV2000 hr " ¹ and 58 mol% of hydrogen, 29 mol% of carbon monoxide, A synthesis gas with a composition of 6 mol% of carbon and 7 mol% of methane was obtained.

 From this composition, the obtained synthesis gas can be used as a raw material in the production of lower paraffin.

 (Example 1)

 LPG was manufactured using the LPG manufacturing apparatus shown in FIG. The reforming catalyst (synthesis gas production catalyst) and the lower paraffin production catalyst used were prepared as follows.

 (Preparation of reforming catalyst)

Magnesium oxide calcined at 920 ° C for 2 hours in air was sized to 0.27 to 0.75 mm, and Ru was supported by impregnation. The Ru-impregnated body was obtained by repeatedly dropping an aqueous solution of ruthenium (III) chloride hydrate (Ru content: 1.0% by weight) into calcined MgO little by little and shaking. And this Ru impregnated body After drying in air at 120 ° C for 2.5 hours, it was calcined in air at 920 ° C for 2 hours to obtain a reforming catalyst (1 ^ 11 supported ^ [0 catalyst).

Obtained: Ru-supporting MgO catalyst, 1. 5x 10- ³ g supported amount of Ru is relative to MgO 1 g, is 0. 06mo 1% by mo 1 terms, a surface area of 9. 6 m ² / g Atsushi.

 (Preparation of catalyst for lower paraffin production)

As a methanol synthesis catalyst component, a commercially available Cu—Zn-based methanol synthesis catalyst (manufactured by Nippon Sudohemi Co., Ltd.) that was mechanically powdered was used. The Zeorai preparative catalyst _{Ingredients, S i0 2 / Al 2 0} 3 molar ratio which is separately prepared proton type Z SM- 5 Zeorai bets 14. 5 (pore diameter: minor 0. 53 nm, major axis 56 nm) powder Using.

 This methanol synthesis catalyst component and the same weight of zeolite catalyst component are uniformly mixed, press-molded and sized, and then reduced at 300 ° C for 3 hours in a hydrogen stream to obtain a lower paraffin production catalyst. Obtained.

 (Syngas production process)

 After the above-mentioned reforming catalyst was charged into an externally heated reaction tube type apparatus, the catalyst was reduced in a hydrogen stream at 900 ° C. for 1 hour before the reaction.

7.8 mol% of natural gas, 14.3 mol% of steam, 3.9 mol% of carbon dioxide, and 74 mol% of low-boiling components separated from the lower paraffin-containing gas described below and recycled as a raw material for syngas production Was passed through the reforming catalyst layer. The reaction conditions, reaction temperature 870 ° C, the reaction pressure 2. LMPA, was GHS V (gas space velocity) 2000 hr ^1.

Analysis of the product (synthesis gas) by gas chromatography revealed that the composition was 44 mol% of hydrogen, 43 mol% of carbon monoxide, 6 mol% of carbon dioxide, and 7 mol% of methane. The resulting synthesis gas contains carbon monoxide and hydrogen in a CO: H ₂ = 1: 1.0 (molar ratio).

(Low-grade paraffin production process) The synthesis gas obtained in the synthesis gas production process was passed through the lower paraffin production catalyst layer. The reaction conditions were a reaction temperature of 325 ° C, a reaction pressure of 2.0 MPa, and GHS V3000 hr- ¹ .

When the product (lower paraffin-containing gas) was analyzed by gas chromatography, the conversion of carbon monoxide was 72%, the shift conversion of carbon monoxide to carbon dioxide was 36%, and the conversion to hydrocarbons was 36%. The conversion was 36%. Propane and butane accounted for 70% of the generated hydrocarbons on a carbon basis, and the breakdown of propane and butane was 41% propane on a carbon basis and 59% _S -butane. The content of low-boiling components (excluding hydrogen) in the lower paraffin-containing gas was 69% on a carbon basis.

 (Separation and recycling process)

 After gas-liquid separation of the lower paraffin-containing gas obtained in the lower paraffin production process, the lower paraffin-containing gas is dried by a molecular sieve and bubbled into an octane solution maintained at about 0 ° C. A gas consisting of 0.6 mol% of methane, 0.8 mol% of ethane and ethylene, 39 mol% of carbon dioxide, 22 mol% of unreacted carbon monoxide and 38 mol% of hydrogen was separated as a low-boiling component, and LPG was separated. Was manufactured.

 The separated low-boiling components were pressurized to 2.5 MPa by a compressor and then recycled as raw materials for the synthesis gas production process.

 (Comparative Example 1D

In the synthesis gas production process, the raw material gas composition is separated from natural gas 14.7 mol%, steam 14.8 mol%, carbon dioxide 3.5 mol%, and gas containing lower paraffin, and recycled as a raw material for syngas production. 67.0 mol% of low-boiling components, reaction temperature of 870 °, reaction pressure of 2. IMP a, GHSV of 2000 hr " ¹ , 58 mol% of hydrogen, 29 mol% of carbon monoxide, 6 mol of carbon dioxide % Of methane and 7 mol% of methane, and LPG was produced in the same manner as in Example 1 except that a lower paraffin-containing gas was produced from this synthesis gas. The synthesis gas obtained above contains carbon monoxide and hydrogen in CO: H ₂ = l: 2 (molar ratio).

 The product in the lower paraffin production process (lower paraffin-containing gas before the separation of low-boiling components) was analyzed by gas chromatography. The conversion of carbon monoxide was 73%. The conversion to shift reaction to methane was 34%, and the conversion to hydrocarbons was 37%. Propane and butane accounted for 78% of the generated hydrocarbons on a carbon basis, and the proportion of propane and butane was 40% for propane and 60% for butane on a carbon basis. The content of low-boiling components (excluding hydrogen) in the gas containing lower paraffins was 69% on a carbon basis.

 In the separation-recycling process, the composition of low-boiling components separated from the lower paraffin-containing gas was 0.7 mol% of methane, 1.2 mol% of ethylene and ethylene, 15 mol% of carbon dioxide, The content was 10 mol% of carbon monoxide and 73 mol% of hydrogen.

 In Comparative Example 1, the amount of low boiling components contained in the lower paraffin-containing gas produced from the synthesis gas was larger than that in Example 1. Specifically, in Comparative Example 1, the content of low-boiling components (carbon-containing low-boiling components) other than hydrogen in the lower paraffin-containing gas was the same as in Example 1, but the content of lower paraffin-containing gas was lower. Has a large hydrogen content. In Comparative Example 1, the entire low-boiling component separated from the lower paraffin-containing gas could not be recycled as a raw material in the synthesis gas production process. Available items

 As described above, according to the present invention, propane and / or butane can be produced from carbon-containing raw materials such as natural gas or synthesis gas with high selectivity.

 Further, according to the present invention, it is possible to more economically produce LPG having a low concentration of components having 2 or less carbon atoms and a high concentration of propane and / or butane from a carbon-containing raw material such as natural gas or a synthesis gas. Can be.

Claims

The scope of the claims

1. (i) In the presence of a catalyst, a lower gas containing a low-boiling component that is a substance having a boiling point or sublimation point lower than that of propane from a synthesis gas, and the main component of the contained hydrocarbon is propane or butane. A lower paraffin production process for producing a paraffin-containing gas;

 (ii) a step of separating the low-boiling component from the lower paraffin-containing gas to obtain a liquefied petroleum gas containing propane or propylene as a main component;

A method for producing a liquefied petroleum gas containing propane or butane as a main component, comprising:

2. (i) and carbon-containing starting material, at least the one H ₂ 0, 0 that is selected from ₂ and C0 ₂ made of the group, is separated from the lower-paraffin-containing gas in the separation step, the synthesis gas production step in degree Recycling et A synthesis gas production process for producing synthesis gas from low-boiling components recycled as raw materials;

 (ϋ) In the presence of a catalyst, from the synthesis gas, contains a low-boiling component that is a substance having a boiling point or a sublimation point lower than the boiling point of propane, and contains a lower paraffin in which the main component of the contained hydrocarbon is propane or butane. A low-grade paraffin production process for producing gas;

 (iii) a step of separating the low-boiling component from the lower paraffin-containing gas to obtain a liquefied petroleum gas containing propane or butane as a main component,

 (iv) a recycling process for recycling the separated low-boiling components as a raw material in a synthesis gas production process.

A method for producing a liquefied petroleum gas containing propane or butane as a main component, comprising:

3. (i) In the presence of a catalyst, CO: H ₂ = 1: 0.5-1 : Lower paraffins containing low-boiling components that are substances having a boiling point or sublimation point lower than the boiling point of propane from the synthesis gas containing 1.4 (molar ratio), and the main component of the contained hydrocarbon is propane or butane. A low-grade paraffin production process for producing a contained gas;

 (ii) a separation step of separating the low-boiling component from the lower paraffin-containing gas obtained in the lower paraffin production step to obtain a liquefied petroleum gas mainly containing propane or butane;

A method for producing a liquefied petroleum gas containing propane or butane as a main component, comprising:

4. (i) The carbon-containing raw material, at least one selected from the group consisting of H ₂ 〇, O ₂ and CO ₂ , and separated from the lower paraffin-containing gas in the separation step, A synthesis gas production process for producing a synthesis gas containing carbon monoxide and hydrogen in a ratio of CO: H ₂ = 1: 0.5 to 1: 1.4 (molar ratio) from low-boiling components recycled as raw materials. ,

 (ii) The synthesis gas obtained in the synthesis gas production process in the presence of a catalyst contains low-boiling components that are substances having a boiling point or sublimation point lower than the boiling point of propane, and the main component of the contained hydrocarbon is propane. Or a lower paraffin production process for producing a lower noraffin-containing gas that is butane;

 (iii) a separation step of separating the low-boiling component from the lower paraffin-containing gas obtained in the lower paraffin production step to obtain a liquefied petroleum gas mainly containing propane or butane;

 (iv) recycling the low-boiling components separated from the lower paraffin-containing gas in the separation process as a raw material in the synthesis gas production process;

A method for producing a liquefied petroleum gas containing propane or butane as a main component, characterized in that:

5. The method for producing a liquefied petroleum gas according to claim 4, wherein in the synthesis gas production process, the content of the recycled low-boiling component in the raw material is 40 to 75 mol%.

6. The liquid according to any one of claims 3 to 5, wherein the content of low-boiling components (excluding hydrogen) in the lower paraffin-containing gas produced in the lower paraffin production step is 60% or less on a carbon basis. A method for producing dani petroleum gas.

7. The liquefied petroleum gas according to any one of claims 1 to 4, wherein the low-boiling component is at least one selected from the group consisting of hydrogen, carbon monoxide, carbon dioxide, ethane, ethylene and methane. Manufacturing method.