JP4486330B2 - Hydrodesulfurization catalyst and hydrodesulfurization method for gasoline fraction - Google Patents

Description

  The present invention relates to a hydrodesulfurization catalyst and hydrodesulfurization method for a gasoline fraction that can sufficiently suppress a decrease in octane number and has a high selective hydrodesulfurization ability.

  Currently, for global warming gas typified by carbon dioxide, frameworks for emission regulations are being developed both at home and abroad, and measures to reduce them are becoming an increasingly important issue. One of the reduction measures is to suppress carbon dioxide emissions from a transport internal combustion engine equipped with a gasoline engine. In order to achieve this, improvement in fuel efficiency of the engine is an essential condition. Therefore, it is considered that the spread of new systems such as a direct injection engine or a lean burn engine, which are engine systems that can improve fuel efficiency relatively, will be further promoted in the future.

  However, in these new systems, when a three-way catalyst that is a conventional NOx removal catalyst in exhaust gas is used, there is a problem that NOx cannot be sufficiently removed. In response to these problems, new NOx removal catalysts have been proposed. However, these NOx removal catalysts are generally easily poisoned by sulfur, thereby reducing the NOx removal activity. Therefore, it is necessary to reduce the sulfur content of gasoline fuel itself, and recently, the necessity of gasoline having a sulfur content of 10 mass ppm or less (so-called sulfur-free gasoline) is being discussed.

  By the way, as a method for producing a gasoline base material, a gasoline fraction obtained by reforming a straight-run gasoline fraction obtained by distillation of crude oil or a gasoline fraction obtained by decomposition of heavy oil can be appropriately treated. Can be mentioned. Among these, the catalytic cracking gasoline fraction obtained from a fluid catalytic cracking unit (FCC) is characterized by being rich in olefins and aromatics and having a high octane number compared to straight-run gasoline.

  However, when trying to hydrodesulfurize a gasoline fraction containing olefins, the hydrodesulfurization reaction and the olefin hydrogenation reaction proceed at the same time, so the octane number of the gasoline fraction via the hydrodesulfurization process decreases. There was a big problem of doing it. Therefore, the hydrodesulfurization process of gasoline fractions including such catalytic cracking gasoline fractions has a selectivity that suppresses the hydrogenation reaction of olefins and promotes only the hydrodesulfurization reaction, so-called “selection”. It is required to be a “hydrohydrodesulfurization process”.

In order to meet the requirements for the selective hydrodesulfurization process described above, for example, Patent Document 1 discloses that the octane number decreased by the hydrotreatment after the hydrotreatment, through the catalytic reforming step or the isomerization step. A method to recover is described. Patent Document 2 describes a method for producing a gasoline fraction through a hydrogenation step of an unsaturated sulfur-containing compound and a decomposition step of the saturated sulfur-containing compound. In addition to this, a method using a catalyst in which the supported amounts of Mo and Co and the surface area of the support are controlled (see Patent Document 3), a method for preventing a decrease in octane number by combining with a zeolite catalyst (see Patent Document 4), and a certain amount A method using a pretreated catalyst (see Patent Document 5) has been proposed.
JP-T 6-509830 JP 2000-239668 A Special Table 2000-505358 US Pat. No. 5,352,354 U.S. Pat. No. 4,149,965

  However, the present inventors have examined the prior art described in these patent documents in detail, and in these prior arts, the sulfur content in the gasoline fraction could be reduced to 10 ppm by mass or less. However, it became clear that the decrease in octane number could not be sufficiently suppressed. In addition, it has been found that these conventional techniques require a special equipment configuration, and furthermore, the operating conditions must be managed for each process. Therefore, it is not always efficient considering the cost of capital investment. .

  Therefore, the present invention has been made in view of the above circumstances, and hydrogenation of olefins that occur as a side reaction when hydrodesulfurizing a catalytic cracked gasoline fraction, which is one of the important constituent base materials of gasoline, is performed. A gasoline distillate having a sufficiently high selective hydrodesulfurization capacity that can sufficiently suppress and maintain the octane number and sufficiently reduce the sulfur content in the catalytic cracked gasoline distillate after hydrodesulfurization. It is an object of the present invention to provide a hydrodesulfurization catalyst and hydrodesulfurization method.

  As a result of intensive studies to achieve the above object, the present inventors inhibit the hydrodesulfurization reaction by using a catalyst in which the support is modified with a specific metal oxide in a hydrodesulfurization process of a gasoline fraction. The inventors have found that only hydrogenation of olefins can be sufficiently suppressed without arriving at the present invention.

That is, the hydrodesulfurization catalyst of the gasoline fraction of the present invention is mainly composed of alumina, and the content of silica, silica alumina, boria, titania, magnesia and their composite oxides and phosphorus is 5 masses relative to the support mass. At least one metal selected from the group consisting of yttrium, scandium, and lanthanoid metals that modify the carrier, and a carrier that is not more than% (except for silica-containing alumina that has a silica content of 2% by weight or more). a metal oxide having, supported on the carrier, and at least one active metal at least selected from one member of the group consisting of active metal and the group 8 metal selected from 6A Zokukin genus or Ranaru group, a It is characterized by including. At this time, the mass ratio of the metal oxide to the mass of the carrier is more preferably 0.3 to 30% by mass.

  The metal oxide is preferably a metal oxide having at least one metal selected from the group consisting of yttrium, lanthanum, cerium, neodymium, samarium and ytterbium, and is selected from the group consisting of yttrium, cerium and ytterbium. It is more preferable to use a metal oxide having at least one metal, and it is more preferable to use ytterbium oxide. Hydrodesulfurization catalysts for gasoline fractions using such metal oxides tend to exhibit very high hydrodesulfurization selectivity.

  Furthermore, the hydrodesulfurization catalyst of the gasoline fraction of the present invention is preferably used for hydrodesulfurization of a gasoline fraction containing 70% by volume or more of the catalytic cracking gasoline fraction, since the effect can be further exhibited. .

  Further, the hydrodesulfurization catalyst carries 10 to 20% by mass in terms of metal oxide with respect to the mass of the hydrodesulfurization catalyst, as the active metal, at least one metal selected from the group consisting of group 6A metals. And at least one metal selected from the group consisting of Group 8 metals is preferably supported in an amount of 3 to 6% by mass in terms of metal oxide with respect to the mass of the hydrodesulfurization catalyst.

  Further, the hydrodesulfurization catalyst is obtained by adding the metal oxide to an alumina precursor and then calcining to obtain a carrier modified with the metal oxide, and carrying the active metal on the carrier. preferable.

  Although it has not been clarified at present whether the hydrodesulfurization catalyst of the present invention exhibits high hydrodesulfurization selectivity, the present inventors consider as follows. That is, the metal oxide used for the modification of the carrier selectively interacts with the hydrogenation active sites of the olefin, thereby suppressing the activity and generating mercaptan, which is one of the causes of decreasing the desulfurization rate. It is considered that the reaction of by-product hydrogen sulfide that causes the reaction is inhibited. However, the factor is not limited to this.

  As explained above, according to the hydrodesulfurization catalyst of the present invention and the hydrodesulfurization method using the same, particularly when hydrodesulfurizing feedstock containing a catalytic cracked gasoline fraction containing a large amount of olefin, By suppressing the olefin hydrogenation reaction, it is possible to sufficiently suppress the decrease in octane number. Thereby, the hydrodesulfurization catalyst and the hydrodesulfurization method can have high selectivity for the hydrodesulfurization reaction. Therefore, by adopting the hydrodesulfurization catalyst of the present invention and the hydrodesulfurization method using the same, a gasoline base material capable of producing sulfur-free gasoline having a sulfur content of 10 mass ppm or less is excessively capital investment. It becomes possible to manufacture efficiently without carrying out.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

First, an embodiment of the hydrodesulfurization catalyst (hereinafter simply referred to as “desulfurization catalyst”) of the gasoline fraction of the present invention will be described. The desulfurization catalyst of this embodiment is mainly composed of alumina as a carrier from the viewpoint of increasing the specific surface area of the catalyst. The alumina is preferably porous γ-alumina (γ-Al ₂ O ₃ ), but may be α-alumina, β-alumina, amorphous alumina, or the like.

In addition to the above, the support includes silica (SiO ₂ ), silica alumina (SiO ₂ / Al ₂ O ₃ ), boria (B ₂ O ₃ ), titania (TiO ₂ ), magnesia (MgO), or a composite thereof. An oxide or the like may be included, and phosphorus may be included. These contents are preferably 5% by mass or less based on the mass of the carrier. When these contents are more than 5% by mass with respect to the mass of the support, coke generation is promoted by expressing acid properties on the desulfurization catalyst, which affects the hydrodesulfurization activity of the desulfurization catalyst.

  Alumina, the main component of the support, is via an alumina intermediate from either a method of neutralizing or hydrolyzing aluminum salts and aluminates, or a method of hydrolyzing aluminum amalgam or aluminum alcoholate. In addition to these methods, a commercially available alumina intermediate or boehmite powder may be used as a precursor.

  The carrier of the desulfurization catalyst of this embodiment is modified with a metal oxide having at least one metal selected from the group consisting of yttrium, scandium and lanthanoid metals. Among these, the carrier of the desulfurization catalyst of the present embodiment is preferably modified with a metal oxide having at least one metal selected from the group consisting of yttrium, lanthanum, cerium, neodymium, samarium and ytterbium. More preferably, it is modified with a metal oxide having at least one metal selected from the group consisting of cerium and ytterbium, and more preferably modified with ytterbium oxide. The ratio of the mass of these metal oxides is preferably 0.3 to 30% by mass, more preferably 0.5 to 20% by mass, and 0.7 to 10% by mass with respect to the mass of the support. And more preferably 0.9 to 5% by mass. When the ratio of the mass of the metal oxide is more than 30% by mass, the hydrodesulfurization activity of the desulfurization catalyst tends to decrease, and when it is less than 0.3% by mass, the hydrodesulfurization selectivity by modification is reduced. There is a tendency not to be recognized.

  In this embodiment, it is not clear what mechanism the desulfurization catalyst exhibits high selectivity. For example, the metal oxide as described above selectively interacts with the hydrogenation active site of the olefin, and its activity It is conceivable that the reaction of by-product hydrogen sulfide causing mercaptan production, which is one of the factors that lower the desulfurization rate, is inhibited.

  The desulfurization catalyst of this embodiment carries at least one metal selected from the group consisting of Group 6A metals and Group 8 metals as active metals. At that time, it is preferable to support at least one metal selected from the group consisting of Group 6A metals and at least one metal selected from the group consisting of Group 8 metals. Specific examples of such active metal combinations include cobalt-molybdenum, nickel-molybdenum, cobalt-tungsten, nickel-tungsten, cobalt-nickel-molybdenum, and the like. Of these, the cobalt-molybdenum combination is more preferable because the hydrodesulfurization activity tends to be particularly high and the olefin hydrogenation reaction tends to be suppressed.

  The amount of the active metal supported is not particularly limited, but is preferably 10 to 20% by mass of the group 6A metal and 3 to 6% by mass of the group 8 metal in terms of metal oxide with respect to the desulfurization catalyst mass, More preferably, the group metal is 12 to 18% by mass, the group 8 metal is 3.5 to 5.5% by mass, the group 6A metal is 13 to 17% by mass, and the group 8 metal is 4 to 5.3% by mass. More preferably.

  The desulfurization catalyst of the present embodiment described above can be prepared by a conventional method, for example, as follows. First, in order to obtain a carrier, an “alumina precursor” such as an alumina gel-containing liquid, boehmite powder, alumina suspension or kneaded product obtained by a conventional method is prepared. Next, in order to introduce a metal oxide that modifies the support, the metal acetate, chloride, nitrate, sulfate, naphthenate, trifluoromethanesulfonate, or various coordination compounds are added to water or an organic solvent. The dissolved material is added to the alumina precursor or blended by a method such as coprecipitation. Among these, it is preferable to use acetate or nitrate, and it is more preferable to use acetate. If trace amounts of sulfate or chloride counter anions remain, the acid properties of the alumina surface may be modified to affect hydrodesulfurization selectivity. A carrier is obtained by kneading, drying, molding, firing, and the like as necessary. The metal oxide for modifying the carrier is obtained by firing the carrier and then dissolving the metal acetate, chloride, nitrate, sulfate, naphthenate or various coordination compounds in water or an organic solvent. You may introduce | transduce by impregnating a support | carrier.

  The modification of the carrier with these metal oxides is described below from the viewpoint of preventing these metal oxides from covering the active sites composed of the 6A group metal or the 8th group metal and reducing the desulfurization activity. It is preferable to carry out before the impregnation support of the group metal or group 8 metal.

  Then, impregnating with active metal carbonate, nitrate, sulfate, organic acid salt or oxide aqueous solution or water-soluble organic solvent or water-insoluble organic solvent as the active metal raw material It is supported on a carrier by a supporting method used in a conventional hydrodesulfurization catalyst such as an ion exchange method. When a plurality of metals are supported, they may be supported simultaneously using a mixed solution, or may be sequentially supported using a single solution. The active metal may be supported on the support after completion of the entire preparation process of the support, or after the active metal is supported on an appropriate oxide, composite oxide, zeolite, or the like in the intermediate process of the support preparation, Processes such as a blending process, heat compression, and kneading may be performed, but it is preferable to perform the process after the completion of the entire carrier preparation process. Then, the desulfurization catalyst of the present embodiment can be obtained by firing the impregnated and supported active metal under desired conditions.

  The desulfurization catalyst of this embodiment can adjust the average pore diameter, the pore volume, or the specific surface area by changing various conditions during the preparation of the desulfurization catalyst described above, as in the conventional method.

  The average pore diameter of the desulfurization catalyst is preferably 3 to 10 nm, and more preferably 5 to 9 nm. When the average pore diameter is smaller than 3 nm, the reaction molecules tend not to diffuse sufficiently in the pores. When the average pore diameter is larger than 10 nm, the surface area of the desulfurization catalyst is decreased, leading to a decrease in activity.

  Moreover, it is preferable that the pore volume of the desulfurization catalyst of this embodiment is 0.3 mL / g or more. When the pore volume is smaller than this, the metal impregnation operation to the desulfurization catalyst tends to be difficult.

Furthermore, the specific surface area of the desulfurization catalyst is preferably 200 m ² / g or more. From the viewpoint of the activity of the desulfurization catalyst, the specific surface area should be as high as possible. However, when the specific surface area is smaller than 200 m ² / g, the area on which the active metal can be supported is decreased, so that the activity tends to decrease particularly. . The specific surface area and pore volume of the desulfurization catalyst are determined by a nitrogen gas adsorption method based on the BET method, and the average pore diameter is calculated from the specific surface area and the pore volume.

  The desulfurization catalyst of this embodiment can be used as a desulfurization catalyst in a hydrodesulfurization process after preliminary sulfidation in the same manner as a general hydrodesulfurization catalyst. This preliminary sulfidation method is performed, for example, by passing straight-run naphtha or a sulfiding agent or a mixture thereof through the desulfurization catalyst, and applying heat of 180 ° C. or higher according to a predetermined procedure under hydrogen pressure conditions. By this preliminary sulfidation, the active metal on the desulfurization catalyst becomes sulfurized and the hydrodesulfurization activity can be exhibited. As the sulfurizing agent, sulfur compounds such as dimethyl disulfide or polysulfide are generally used. Note that the desulfurization catalyst may be subjected to sulfurization treatment in advance before being filled in the catalyst layer of the hydrodesulfurization process, and is subjected to activation treatment with a sulfur-containing, oxygen-containing or nitrogen-containing organic solvent. Also good.

  The catalyst of the present embodiment as described above is a high hydrodesulfurization selection that can sufficiently suppress the hydrogenation of olefins while sufficiently removing the sulfur content in the gasoline fraction by the hydrodesulfurization reaction. It has sex. Therefore, the gasoline fraction obtained using the catalyst can sufficiently meet the demand for sulfur-free gasoline and can be kept sufficiently high without reducing the octane number.

  Next, an embodiment of the hydrodesulfurization method (hereinafter simply referred to as “desulfurization method”) of the gasoline fraction of the present invention will be described. The desulfurization method of the present embodiment performs a hydrotreatment by passing a gasoline fraction used as a raw material oil through a catalyst layer filled with a hydrodesulfurization catalyst of the present invention together with hydrogen gas under predetermined reaction conditions. The product oil is obtained.

  The gasoline fraction used as the feedstock in the present embodiment preferably contains a gasoline fraction distilled from a fluid catalytic cracking unit (FCC) from the viewpoint of further exerting the effect of the desulfurization catalyst. The gasoline fraction usually contains about 10 to 1000 ppm by mass of sulfur. Examples of the sulfur component include thiophene, alkylthiophene, benzothiophene, alkylbenzothiophene, thiacyclopentane, alkylthiacyclopentane, mercaptan compound, or sulfide compound. Moreover, n-olefin or isoolefin is mentioned as an olefin content contained in this gasoline fraction.

  The gasoline fraction preferably contains a sulfur content of 250 mass ppm or less, more preferably 200 mass ppm or less. When the sulfur content is higher than 250 ppm by mass, a higher desulfurization rate is required. Therefore, by adjusting the reaction temperature or the like, olefin hydrogenation tends to proceed as a result.

  The olefin content in the gasoline fraction is preferably 10 to 50% by volume, more preferably 15 to 45% by volume, and even more preferably 20 to 40% by volume. When the olefin content is less than 10% by volume, the effects of the present invention tend not to be fully exhibited. When the olefin content is more than 50% by volume, the olefin hydrogenation reaction tends not to be sufficiently suppressed, and the addition reaction of hydrogen sulfide produced as a by-product with the desulfurization of the thiophene compound to the olefin occurs. Since it proceeds, the hydrodesulfurization reaction tends not to proceed sufficiently.

  In addition to this, the feedstock used in this embodiment has a boiling point of 30 to 30 such as a gasoline fraction obtained from an atmospheric distillation apparatus, a gasoline fraction produced from various hydrorefining equipment, or a gasoline fraction produced by thermal decomposition. A fraction of about 250 ° C. may be included. In this case, the feedstock oil preferably contains 70% by volume or more of catalytic cracked gasoline fraction, more preferably 80% by volume or more, from the viewpoint of further exerting the effects of the present invention. When the catalytic cracking gasoline fraction is less than 70% by volume, the content of the olefin in the raw material oil is small, and thus the effects of the present invention tend not to be fully exhibited.

  Further, the boiling range of the gasoline fraction of the feedstock used in this embodiment is not particularly limited as long as it is a normal gasoline fraction boiling range, but the initial boiling point is 30 ° C. or higher and the end point is 250 ° C. or lower. It is preferable. If the initial boiling point is lower than 30 ° C, it tends to be difficult to satisfy the vapor pressure and distillation property standards in the gasoline standard defined in JIS K2202 “Automobile Gasoline”. Of the gasoline standards defined in JIS K2202, it is difficult to satisfy the vapor pressure standards, and the content of high-boiling compounds having low desulfurization reactivity increases, so that desulfurization itself tends to be difficult.

In addition, the “content of sulfur content” in this specification is the sulfur content based on the total amount of gasoline fraction measured according to JIS K2541 “Sulfur content test method” or the method described in ASTM-D5453. Mean mass content. The “desulfurization rate” is defined by the following formula (1), where S ₀ is the sulfur content in the feed oil and S is the sulfur content in the product oil.
(Desulfurization rate) <%> = 100− (S / S ₀ ) × 100 (1)

“Olefin content” is determined from the bromine number based on the gasoline fraction, which is measured according to the method described in JIS K2605 “Petroleum products—Bromine test method—Electro titration method” or ASTM-D1492. Means an estimate. The “olefin hydrogenation rate” indicating how much olefin content in the feedstock has been hydrogenated is given by the following formula (2) where the bromine number of the feedstock oil is B ₀ and the bromine number of the product oil is B: Defined by
(Olefin hydrogenation rate) <%> = 100− (B / B ₀ ) × 100 (2)

  The octane number of the gasoline fraction is measured by a research method, and more specifically, according to the method described in JIS K2280 “Testing method for octane number and cetane number and cetane index calculation method” or ASTM-D2699.

  The catalytic cracking gasoline fraction used in the feedstock oil contains a relatively large amount of sulfur in the heavy gasoline fraction (high boiling fraction), while the olefin content in the light gasoline fraction (low boiling fraction). There is a tendency to include a relatively large amount. Therefore, the catalytic cracking gasoline fraction may be further fractionated into a light gasoline fraction and a heavy gasoline fraction, and a heavy gasoline fraction having a relatively low olefin content may be used as the feedstock. More specifically, for example, a light gasoline fraction having a boiling point of 30 ° C. to 180 ° C. and a heavy gasoline fraction of 80 ° C. to 250 ° C. are fractionated in advance, and only the heavy gasoline fraction is described above. The hydrodesulfurization catalyst layer can also be circulated. Thereby, hydrodesulfurization of a gasoline fraction can be performed more efficiently.

  The reaction pressure in the desulfurization method of the present embodiment is 1 to 5 MPa, more preferably 1 to 3 MPa, and further preferably 1.2 to 2.5 MPa. When the reaction pressure is higher than 5 MPa, the by-produced hydrogen sulfide is added to the olefin in the raw material oil to produce a mercaptan compound, thereby reducing the desulfurization rate. When the reaction pressure is lower than 1 MPa, the hydrodesulfurization reaction does not proceed sufficiently.

The LHSV (liquid space velocity) in the catalyst layer in the present embodiment is ¹ to 10 h ⁻¹ , preferably 1.5 to 8 h ⁻¹ , and more preferably 2 to 5 h ⁻¹ . When the LHSV is lower than 1 h ⁻¹ , the olefin hydrogenation reaction is promoted, so that the octane number of the resulting oil decreases. On the other hand, when it is higher than 10 h ⁻¹ , the hydrodesulfurization reaction does not proceed.

“LHSV (liquid hourly space velocity)” refers to the volume flow rate of the raw material oil in the standard state (25 ° C., 101325 Pa) per volume of the catalyst layer filled with the catalyst, The unit “h ⁻¹ ” indicates the reciprocal of time (hour).

  Moreover, the reaction temperature in a catalyst layer is 190-300 degreeC, It is more preferable in it being 200-295 degreeC, and it is more preferable in it being 210-290 degreeC. When the reaction temperature is lower than 190 ° C., sufficient hydrodesulfurization cannot be performed. Moreover, when reaction temperature is higher than 300 degreeC, there exists a possibility that an olefin hydrogenation reaction may advance rapidly and runaway reaction may be caused.

  Furthermore, the hydrogen / oil ratio, which is the ratio of the raw oil to the accompanying hydrogen gas, is 100 to 600 NL / L, preferably 200 to 500 NL / L, and more preferably 250 to 450 NL / L. When the hydrogen / oil ratio is lower than 100 NL / L, hydrogen sulfide in the system cannot be sufficiently removed, so that the addition reaction of hydrogen sulfide to olefin cannot be suppressed. In addition, when the hydrogen / oil ratio is higher than 600 NL / L, the gasoline fraction and the catalyst cannot be sufficiently contacted, so that a desired reaction activity cannot be obtained, leading to a huge capital investment as equipment and economically. It is not preferable.

  Note that “NL”, which is a unit of hydrogen capacity in the hydrogen / oil ratio, indicates a hydrogen capacity (L) in a normal state (0 ° C., 101325 Pa).

  In this embodiment, the reaction conditions are adjusted within the above range so that the desulfurization rate is 90% or more, more preferably 93% or more, and the olefin hydrogenation rate is 40% or less. Thereby, the base material of sulfur free gasoline can be obtained from produced | generated oil, and the high octane number of the gasoline base material can be maintained. When the desulfurization rate or olefin hydrogenation rate is not within the above range, the superiority of high hydrodesulfurization selectivity, which is the effect of the present invention, is reduced.

  The product oil obtained in the present embodiment preferably has a sulfur content of 10 mass ppm or less, and more preferably 5 mass ppm or less. When the sulfur content in the product oil is 10 mass ppm or less, a sulfur-free gasoline base material can be obtained from this product oil, and the impact on the exhaust gas cleaning device of the gasoline engine can be minimized. It becomes.

  In this way, the apparatus for hydrotreating the feedstock oil may have any configuration, and the reaction towers filled with the catalyst layer may be used alone or in combination. For the purpose of reducing the hydrogen sulfide concentration in the reaction tower, Alternatively, a gas-liquid separation facility or other hydrogen sulfide removal facility may be provided between the plurality of reaction towers.

  Moreover, as a reaction format of the hydrotreating apparatus used in the present embodiment, a fixed bed system may be used. That is, hydrogen can take either a countercurrent or a cocurrent flow with respect to the raw material oil, or a combination of countercurrent and cocurrent flow having a plurality of reaction towers. The general format is downflow, and there is a gas-liquid twin parallel flow format. The reaction tower may be composed of a plurality of catalyst beds, and hydrogen gas may be injected between each catalyst bed for the purpose of removing reaction heat or increasing the hydrogen partial pressure (quenching hydrogen).

In the desulfurization method in the present embodiment, hydrogen gas is accompanied with the raw material oil as described above, but as an injection method of such hydrogen gas,
(1) From the entrance of the first reaction tower (the reaction tower into which the feedstock is first introduced), or (2) between each catalyst bed or between a plurality of reaction towers,
There are two injection methods. In this embodiment, either (1) alone or both methods (1) and (2) can be adopted, but a method of injecting hydrogen gas from both (1) and (2) is preferable. . In order to more reliably remove by-produced hydrogen sulfide and efficiently proceed with the hydrodesulfurization reaction, preferably 90% by volume or less of the total amount of hydrogen gas injected is injected from (1), and the remaining Hydrogen gas is preferably injected from (2). Further, the amount of hydrogen gas injected from (1) is more preferably 80% by volume or less, more preferably 70% by volume or less, and more preferably 60% by volume or less of the total hydrogen gas injection amount. Particularly preferred. That is, as the amount of the remaining hydrogen gas injected from (2) increases, the effect of adding hydrogen gas tends to be exhibited more efficiently. The inlet of the first reaction tower here may be before the heating furnace for heating the raw material oil to a predetermined temperature or may be the outlet of the heating furnace.

  Since the desulfurization method of the present embodiment described above can sufficiently reduce the sulfur content contained in the product oil, it is extremely useful for producing sulfur-free gasoline. In addition, since the desulfurization method can maintain a high octane number without particularly reducing the octane number of the catalytic cracking gasoline fraction, it is possible to provide gasoline with extremely excellent combustion efficiency. Therefore, the product gasoline manufactured using the product oil obtained by the desulfurization method of this embodiment can contribute to the reduction of environmental load.

  The product oil obtained by the desulfurization method of this embodiment is a mercaptan contained in the raw oil when the sulfur content is relatively low or when a hydrodesulfurization apparatus having a two-stage reaction or the like is used. Since the amount of thiol tends to be small, there is no need to sweeten at a later stage. However, since the produced oil may contain a thiol, it is preferable to provide a gasoline sweetening device after the reaction tower of the hydrodesulfurization unit or after the hydrodesulfurization unit.

  The gasoline base material containing the catalytic cracking gasoline obtained through the desulfurization method of the present embodiment can be used alone as the product gasoline, but it is usually mixed with other gasoline base materials to make the product gasoline. preferable. Various other gasoline base materials can be used, for example, aromatic hydrocarbons from desulfurized straight-run gasoline, pyrolysis gasoline, catalytic reformed gasoline, isomerized gasoline, alkylated gasoline, and catalytic reformed gasoline. For example, a residual residue (sulfolan raffinate) may be used.

  Among these, it is preferable to use contact reformed gasoline having a research octane number (RON) of 95 or more as a gasoline base other than catalytic cracked gasoline. Moreover, it is preferable to prepare such that the proportion of the catalytic reformed gasoline in the product gasoline is 20 to 50% by volume. In this case, the mixing ratio of the gasoline base material obtained through the desulfurization method of the present embodiment is preferably 60% by volume or less. By setting the mixing ratio of the gasoline base to the above range, a large amount of high-quality low-sulfur product gasoline having a high octane number having a sulfur content of 10 mass ppm or less and an olefin content of 10% by volume or more is obtained. Can get to.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

Example 1
In a reaction vessel equipped with a steam jacket, 400 g of aluminum sulfate aqueous solution (alumina concentration 3.9% by mass) and 500 g of sodium aluminate (alumina concentration 1.9% by mass) are mixed while heating to 60 ° C. to obtain an alumina hydrate slurry. Obtained. After the slurry was filtered and washed, 50 ml of 27% aqueous ammonia solution and 100 ml of distilled water were added and stirred at 90 ° C. for 12 hours to obtain alumina hydrate having an alumina concentration of 24%. The obtained hydrate was concentrated and kneaded while maintaining the temperature at 95 ° C., and then 200 mL of an aqueous solution containing 9.6 g of ytterbium acetate tetrahydrate was added. After kneading, it was extruded into a 1/16 inch column, dried at 110 ° C. for 2 hours, and fired at 550 ° C. for 1 hour to obtain a carrier. The ytterbium contained in the carrier was 1.0% by mass in terms of oxide mass.

Subsequently, 330 mL of water was added to 150 g of ammonium molybdate ((NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O) and dissolved by heating. To this aqueous solution, basic nickel carbonate (NiCO ₃ · 2Ni (OH) ₂ · 4H was added. ₂ O) 69 g was added to prepare an impregnation solution. Then, after impregnating and supporting 500 g of the carrier by a pore-filling method, the carrier was baked at 550 ° C. for 2 hours. The catalyst thus obtained had a specific surface area of 250 m ³ / g and a pore volume of 0.48 mL / g. The metal loading was 4.9% by mass for Ni in terms of NiO and 14.9% by mass for Mo in terms of MoO ₃ .

50 g of the obtained catalyst was charged into a fixed bed downflow type bench reactor, and the temperature was gradually raised to 300 ° C. in a hydrogen stream containing 5% by volume of hydrogen sulfide, and presulfided for 4 hours. Subsequently, the temperature is lowered to 230 ° C., the catalytic cracking gasoline having a density at 0.7 ° C. of 0.733 g / cm ³ , a boiling point of 31 to 198 ° C., RON of 91, sulfur content of 90 mass ppm and olefin content of 36% by volume. Hydrodesulfurization was performed under conditions of a temperature of 240 ° C., a pressure of 2 MPa, an LHSV of 4 h ⁻¹ , and a hydrogen / oil ratio of 250 NL / L. As a result, the sulfur content in the obtained product oil was 3.0 ppm by mass (97% desulfurization rate), and the olefin hydrogenation rate was 11% (RON was 90).

(Example 2)
A catalyst was prepared in the same manner as in Example 1 except that an aqueous solution containing 13.0 g of yttrium acetate tetrahydrate was used instead of 9.6 g of ytterbium acetate tetrahydrate. The yttrium contained in the support was 1.1% by mass in terms of oxide weight, the specific surface area of the catalyst was 245 m ³ / g, and the pore volume was 0.44 mL / g. The metal loading was 4.9% by mass for Ni in terms of NiO and 14.9% by mass for Mo in terms of MoO ₃ .

  50 g of the obtained catalyst was presulfided in the same manner as in Example 1. Thereafter, hydrodesulfurization was performed under the same reaction conditions as in Example 1. As a result, the sulfur content in the resulting product oil was 3.3 mass ppm (desulfurization rate 96%), and the olefin hydrogenation rate was 12% (RON was 90).

(Example 3)
A catalyst was prepared in the same manner as in Example 1 except that an aqueous solution containing 10.3 g of cerium acetate monohydrate was used instead of 9.6 g of ytterbium acetate tetrahydrate. The cerium contained in the support was 1.2% by mass in terms of oxide weight, the specific surface area of the catalyst was 240 m ³ / g, and the pore volume was 0.46 mL / g. The metal loading was 4.7% by mass for Ni in terms of NiO and 14.7% by mass for Mo in terms of MoO ₃ .

  50 g of the obtained catalyst was presulfided in the same manner as in Example 1. Thereafter, hydrodesulfurization was performed under the same reaction conditions as in Example 1. As a result, the sulfur content in the resulting product oil was 4.1 mass ppm (desulfurization rate 95%), and the olefin hydrogenation rate was 14% (RON was 89).

Example 4
Alumina hydrate was prepared in the same manner as in Example 1 and concentrated and kneaded while maintaining at 95 ° C., then extruded into a 1/16 inch column, dried at 110 ° C. for 2 hours, and dried at 550 ° C. The carrier was obtained by firing for 1 hour. After impregnating and supporting 310 mL of an aqueous solution containing 5.4 g of ytterbium acetate tetrahydrate on 500 g of the obtained support by the pore filling method, the support was calcined at 550 ° C. for 1 hour. The ytterbium contained in the carrier was 1.2% by mass in terms of oxide weight.

Subsequently, water (220 mL) was added to 100 g of ammonium molybdate ((NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O) and dissolved by heating. Basic nickel carbonate (NiCO ₃ · 2Ni (OH) ₂ · 4H) was dissolved in this aqueous solution. ₂ O) 46 g was added to prepare an impregnation solution. Then, the carrier 330g was impregnated and supported by the pore filling method, and then calcined at 550 ° C. for 2 hours. The catalyst thus obtained had a specific surface area of 250 m ³ / g and a pore volume of 0.48 mL / g. The metal loading was 5.1% by mass for Ni in terms of NiO and 14.9% by mass for Mo in terms of MoO ₃ .

  50 g of the obtained catalyst was presulfided in the same manner as in Example 1. Thereafter, hydrodesulfurization was performed under the same reaction conditions as in Example 1. As a result, the sulfur content in the resulting product oil was 4.8 mass ppm (desulfurization rate 95%), and the olefin hydrogenation rate was 16% (RON was 88).

(Comparative Example 1)
An alumina carrier was obtained in the same manner as in Example 4 except that an aqueous solution containing ytterbium acetate tetrahydrate was not added. Subsequently, 330 mL of water was added to 150 g of ammonium molybdate ((NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O) and dissolved by heating. Basic nickel carbonate (NiCO ₃ · 2Ni (OH) ₂ · 4H ₂ ) was dissolved in this aqueous solution. O) 69 g was added to prepare an impregnation solution. Then, after impregnating and supporting 500 g of the carrier by the pore filling method, it was fired at 550 ° C. for 2 hours. The obtained catalyst had a surface area of 235 m ³ / g and a pore volume of 0.46 mL / g. The metal loading was 4.8% by mass for Ni in terms of NiO and 14.8% by mass for Mo in terms of MoO ₃ .

  50 g of the obtained catalyst was presulfided in the same manner as in Example 1. Thereafter, hydrodesulfurization was performed under the same reaction conditions as in Example 1. As a result, the sulfur content in the resulting product oil was 10.5 ppm by mass (desulfurization rate 88%), and the olefin hydrogenation rate was 44% (RON was 78).

Claims (8)

A carrier containing alumina as a main component and containing silica, silica alumina, boria, titania, magnesia and their composite oxides and phosphorus in an amount of 5% by mass or less based on the mass of the carrier (however, the silica content is 2% by weight) Excluding silica-containing alumina)
A metal oxide having at least one metal selected from the group consisting of yttrium, scandium and a lanthanoid metal that modifies the carrier;
Supported on the carrier, characterized in that it comprises at least one active metal at least one member selected from the group consisting of active metal and the Group 8 metal selected from 6A Zokukin genus or Ranaru group, a , Hydrodesulfurization catalyst for gasoline fractions.   The hydrodesulfurization catalyst for a gasoline fraction according to claim 1, which is used for hydrodesulfurization of a gasoline fraction containing 70% by volume or more of a catalytic cracking gasoline fraction.   The hydrodesulfurization catalyst for a gasoline fraction according to claim 1 or 2, wherein a ratio of the mass of the metal oxide to the mass of the support is 0.3 to 30 mass%.   The metal oxide is a metal oxide having at least one metal selected from the group consisting of yttrium, lanthanum, cerium, neodymium, samarium and ytterbium. The hydrodesulfurization catalyst for gasoline fractions described in 1.   The gasoline fraction according to any one of claims 1 to 3, wherein the metal oxide is a metal oxide having at least one metal selected from the group consisting of yttrium, cerium and ytterbium. Hydrodesulfurization catalyst.   The hydrodesulfurization catalyst for a gasoline fraction according to any one of claims 1 to 3, wherein the metal oxide is ytterbium oxide.   As the active metal, at least one metal selected from the group consisting of Group 6A metals is supported by 10 to 20% by mass in terms of metal oxide with respect to the mass of the hydrodesulfurization catalyst, and Group 8 metal 7. At least one kind of metal selected from the group consisting of 3 to 6% by mass in terms of metal oxide is supported with respect to the mass of the hydrodesulfurization catalyst. The hydrodesulfurization catalyst for gasoline fractions described in the paragraph.   The metal oxide is added to an alumina precursor and then calcined to obtain the carrier modified with the metal oxide, and obtained by loading the active metal on the carrier. The hydrodesulfurization catalyst for a gasoline fraction according to any one of 7 above.