JP5009109B2 - Hydrocarbon partial oxidation catalyst and method and apparatus for producing hydrogen-containing gas using the same - Google Patents

Description

  The present invention relates to a catalyst for a partial oxidation reaction of hydrocarbons, for example, a catalyst for producing a mixed gas containing methane, ethane, propane, or a gas thereof as a main component, or a mixed gas containing hydrogen from natural gas by a partial oxidation reaction. And a method and an apparatus for producing a mixed gas containing hydrogen using the same.

  The reaction of converting methane gas or natural gas into hydrogen and carbon monoxide is not only useful as a method for obtaining synthesis gas as a raw material for chemical products, but also important as a method for producing hydrogen as a clean energy source.

  Fuel cells, on the other hand, emit only water during power generation and are free of vibrations and noise, so they are expected to make a significant contribution to improving energy and environmental issues. However, there are problems with the supply of hydrogen as a fuel. It was. In particular, for fuel cells that are relatively small and dispersedly arranged for small buildings, homes, ships, etc., there is a demand for small fuel supply devices that can supply fuel on the spot.

  Hydrogen production from fossil fuels such as natural gas has been conventionally carried out on a large scale mainly by the steam reforming method, but it is usually operated at a high temperature around 800 ° C., and the steam reforming itself is an endothermic reaction. For this reason, a large amount of energy was required, and a large amount of carbon dioxide as a by-product was released to the atmosphere. It is impossible to connect such a large-scale hydrogen production apparatus to small fuel cells that are dispersedly arranged, and even if hydrogen produced on a large scale is supplied by a cylinder, the transportation cost becomes expensive, This hinders the spread of small fuel cells.

In addition to the steam reforming method, there is a partial oxidation method as a method for producing synthesis gas or hydrogen from hydrocarbons. The reaction for producing hydrogen from the partial oxidation of saturated hydrocarbons is as follows:
_{C x H 2 (x + 1} ) + (x / 2) O 2 → xCO + (x + 1) H 2
Since the partial oxidation reaction is an exothermic reaction, it is not necessary to input a large amount of energy from the outside. However, the reaction temperature tends to be high, the reaction vessel material that can withstand the high temperature is limited, and the life of the apparatus is shortened. Therefore, there is a demand for a catalyst that proceeds the reaction at a relatively low temperature.

  As a partial oxidation catalyst for producing synthesis gas and hydrogen from methane and oxygen, Ru or Rh supported on zirconia or stabilized zirconia (see Patent Document 1), or Ir supported on titanium oxide. However, these catalytically active metals, Ru, Rh, and Ir are all expensive rare noble metals, and practically cheaper partial oxidation catalysts are available. It was sought after.

  In the partial oxidation reaction of hydrocarbons by a catalyst, carbon deposition is likely to occur. In these proposed partial oxidation catalysts, in principle, the reaction is continued as long as the activity of the catalyst continues while continuously supplying methane and oxygen as raw material gases. Therefore, if carbon is deposited on the catalyst surface, the catalyst is inactive. There has been a problem of shortening the service life.

There has also been proposed a Co / Al ₂ O ₃ partial oxidation catalyst in which Co, which is cheaper than a noble metal as a catalytically active metal, is supported on alumina (see Non-Patent Document 2). However, a Co-supported catalyst using alumina as a carrier has not yet been able to be practically used for the conversion rate of fuel gas and the hydrogen selectivity of the product.

Although it is not the partial oxidation reaction which is the subject of the present invention, there is a report using a catalyst in which Ni is supported on a CeO ₂ -Al ₂ O ₃ support for the CO ₂ reforming reaction of methane (see Non-Patent Document 3). ). There, it is concluded that it is optimal when the amount of CeO ₂ is 1 to 5% by weight with the Ni loading fixed at 5% by weight, and the catalyst is also effective for partial oxidation reaction. Whether it was unknown.

  In the conventional partial oxidation method, pure oxygen must be supplied together with methane. For this purpose, it is necessary to connect a gas line from a large-scale oxygen production apparatus to the partial oxidation reaction apparatus, or to transport and connect an oxygen cylinder, which increases the size and cost of the system. It was.

There is a concept of supplying oxygen necessary for the partial oxidation reaction of methane not from pure oxygen but from the catalyst itself. An oxide is used as a catalyst, and lattice oxygen is used. Triiron tetroxide (Fe ₃ O ₄ ), which was studied by Otsuka et al. As a hydrogen storage material, can also be considered as an example of such a catalyst because it also produces hydrogen by methane decomposition (non-patent literature). 4 and 5).

  In addition, research results have recently been reported in which a perovskite oxide is used as a catalyst and methane is partially oxidized using the catalyst's own oxygen to obtain a synthesis gas (see Non-Patent Document 6). In order to design a practical system, there are many problems that are problematic in terms of cost.

The present inventors have developed and announced a novel catalyst using ferric oxide as a catalytically active component as a partial oxidation catalyst with improved problems as described above. (Non-patent Document 7) According to the previous invention, it was necessary to contain yttria as a support, and a high-performance partial oxidation catalyst was obtained by adding rhodium which is a noble metal. Since the amount of rhodium added is small and the active main component is an inexpensive iron oxide, the catalyst of the previous invention is never expensive. However, if the catalyst can be produced from a cheaper and less scarce raw material, it is naturally useful industrially.
JP-A-5-221602 K. Nakagawa, T. Suzuki, T. Kobayashi and M. Haruta, Chem. Lett., (1996) 1029 S. Teng, J. Lin and KL Tan, Catalysis Letter 59 (1999) 129-135 S. Wang and GQ Lu, Applied Catalysis B, 19, (1998) 267-277 Takenaka So, Mitsuko Aiko, Yamanaka Ichiro, Otsuka Kiyoshi, Catalyst, 42 (2000) 351 Takenaka So, Van Tho Dinh Son, Hanaizumi Noriko, Yamanaka Ichiro, Otsuka Kiyoshi, Catalyst, 46 (2004) 146 SHEN Shikong, LI Ranjia, ZHOU Jiping and YU Changchun, Chinese J. Chem. Eng., 11 (2003) 649-655 Osami Nakayama, Na-oki Ikenaga, Takanori Miyake, Eriko Yagasaki and Toshimitsu Suzuki, Europacat VIII, P.11-44 (26-31 Aug. 2007, Finland)

  If hydrocarbons such as methane gas can be used as raw materials to perform partial oxidation with the catalyst's own oxygen and a catalyst that can be regenerated can be found, energy-saving, compact, and quick start-up can replace the conventional steam reforming method. This leads to the production of hydrogen and synthesis gas. Such hydrogen production is optimal for supplying hydrogen to small fuel cells, which are clean distributed power sources, and contributes to the stable supply of energy to society and the improvement of the environment.

The first object of the present invention relates to the production of a hydrogen-containing gas by a partial oxidation reaction of hydrocarbons, which does not require oxygen supply in the partial oxidation reaction step, is inexpensive, can suppress carbon deposition, and can be regenerated. Is to provide.
A second object of the present invention is to provide a method for producing the catalyst.
A third object of the present invention is to provide a method for producing a hydrogen-containing gas using the catalyst.
The fourth object of the present invention is to provide an apparatus for producing a hydrogen-containing gas using the catalyst.

  As a result of intensive studies, the present inventors have found that if a catalyst comprising nickel and chromium oxides and an oxide that plays a role as a carrier is used, hydrocarbons such as methane can be obtained using the oxygen of the catalyst itself. It has been found that the partial oxidation reaction proceeds, the hydrogen selectivity in the product is increased, and carbon deposition can be suppressed. Further, this catalyst is easy to regenerate and is not limited to pure oxygen, but also air or the like. After confirming that it can be reproduced, the present invention has been completed.

  The partial oxidation catalyst of the present invention was developed mainly for showing good activity for partial oxidation reaction of hydrocarbons such as methane without the need to supply oxygen from the outside. Oxidized to produce a mixed gas containing hydrogen and carbon monoxide, characterized by containing nickel and chromium oxides. It is possible for hydrocarbon gas such as methane and the lattice oxygen of the oxide constituting the catalyst itself to react to proceed a partial oxidation reaction that produces synthesis gas mainly composed of hydrogen and carbon monoxide, Lattice oxygen consumed in the reaction can be regenerated by oxidizing the catalyst after the reaction with oxygen, air, etc., so that the catalyst can be used repeatedly.

As the carrier for forming the catalyst of the present invention, various oxides used in ordinary catalysts can be used, but depending on the chemical composition and production method, an excellent partial oxidation catalyst can be obtained and function sufficiently. May not. As the support, magnesia (MgO), silica (SiO ₂ ), and yttria (Y ₂ O ₃ ) are preferable. When alumina (Al ₂ O ₃ ) or ceria (CeO ₂ ) is used, sufficient catalytic activity is obtained. Often not.

  There are various methods for producing the catalyst. The first production method includes a step of preparing a solution in which a salt containing nickel and chromium as metal elements as catalyst components and magnesium, silicon or yttrium metal elements as metal elements as carriers is dissolved; The method includes a drying step of removing the solvent of the solution and a baking step of baking in an oxidizing atmosphere after the drying step. In this case, magnesium, silicon or yttrium is converted into an oxide from the aqueous solution together with the catalyst component. In the present invention, such a form is also called a carrier. Thus, in the catalyst obtained by previously mixing the aqueous solution of the material and evaporating the solvent and then calcining, carbon deposition, which is an undesirable side reaction of the partial oxidation reaction, is suppressed.

  The second production method includes a step of adding a solution in which a salt containing nickel and chromium metal elements is dissolved to magnesium oxide, silica, or yttrium oxide as a carrier, and then a drying step of removing the solvent of the solution. And a baking step of baking in an oxidizing atmosphere after the drying step.

  The method for producing a hydrogen-containing gas of the present invention comprises contacting a raw material gas containing hydrocarbon with the partial oxidation catalyst of the present invention under heating, and oxidizing the metal in the partial oxidation catalyst without supplying an oxygen-containing gas as an oxidant. A partial oxidation step in which hydrocarbons are partially oxidized by lattice oxygen constituting the product to generate a mixed gas containing hydrogen and carbon monoxide, and a partial oxidation catalyst that has undergone the partial oxidation step is brought into contact with an oxygen-containing gas under heating. And a regeneration step for regenerating the partial oxidation catalyst.

  The oxygen-containing gas used in the regeneration process may be pure oxygen gas, but as shown in the examples, it may be a mixed gas of oxygen and an inert gas, or may be water vapor or air. From the viewpoint of cost, it is most preferable to use air.

  The hydrogen-containing gas production apparatus of the present invention comprises a reaction tube holding the partial oxidation catalyst of the present invention, a heating furnace for heating the catalyst, and a raw material gas containing hydrocarbons such as methane is sent to the reaction tube and brought into contact with the catalyst. And a regeneration gas supply passage for sending an oxygen-containing gas used for catalyst regeneration to the reaction tube and bringing it into contact with the catalyst, in a state where no oxygen-containing gas as an oxidant is present in the reaction tube. In the catalyst, the hydrocarbon of the raw material gas is partially oxidized by lattice oxygen constituting the metal oxide in the catalyst to generate a mixed gas containing hydrogen and carbon monoxide, and the regeneration gas supply flow path in the absence of the raw material gas The partial oxidation catalyst is regenerated with the oxygen-containing gas from

  If the reaction tube is a fixed bed reaction tube that is fixed so that the partial oxidation catalyst cannot move, it is possible to regenerate the other catalyst during one partial oxidation reaction if there are two series of reaction tubes. Thus, a continuous hydrogen-containing gas production apparatus can be realized. That is, in that case, two sets of reaction tubes and heating furnaces are provided, and the source gas supply flow path and the regeneration gas supply flow path are connected to both reaction tubes via switching valves, and the heating furnace and switching valve are By controlling this, the catalyst in the other reaction tube is regenerated during the partial oxidation reaction in one reaction tube, and the operation can be switched alternately.

  When the reaction tube is a moving bed reaction tube held in a state where the catalyst is movable, the reaction unit in which the reaction tube performs the partial oxidation reaction and the regeneration unit in which the catalyst regeneration is performed at a location different from the reaction unit And a transport path for transporting the catalyst between the reaction section and the regeneration section is provided, the source gas supply flow path is connected to the reaction section, and the regeneration gas supply flow path is connected to the regeneration section. As a result, the partial oxidation reaction and the catalyst regeneration can be continuously continued while the catalyst is moved.

  In the examples, only methane is taken up as a hydrocarbon as a raw material, but it is not limited to methane. It may be a saturated hydrocarbon such as ethane or propane. However, methane is most preferable because the carbon deposition amount tends to increase as the number of carbon atoms in the hydrocarbon increases. Moreover, although unsaturated hydrocarbon may be used, it is not preferable because the carbon deposition amount tends to increase.

  By using the partial oxidation catalyst of the present invention, a mixed gas containing hydrogen and carbon monoxide can be produced by a partial oxidation method without the need to connect an oxygen supply gas line or an oxygen cylinder for partial oxidation. Hydrogen can be separated from the obtained mixed gas, or a mixed gas of hydrogen and carbon monoxide can be used as a synthesis gas for a raw material for organic compound synthesis. In particular, a hydrogen production apparatus suitable for a small fuel cell can be realized.

  The catalyst composition described in the present invention excludes the preparation of a catalyst by mixing other components for obtaining characteristics generally required for a catalyst, such as improvement in mechanical strength, with the catalyst composition of the present invention. It is not a thing. Further, the catalyst composition described in the present invention does not exclude trace impurity components inevitably mixed in the catalyst production process.

(1) Preparation of MgO support Magnesium nitrate (Mg (NO ₃ ) ₂ · 6H ₂ O) was heated to 600 ° C. under air flow and held for 5 hours to prepare MgO.

(2) Preparation of Y ₂ O ₃ carrier Yttrium oxalate (Wako, Y ₂ (C ₂ O ₄ ) ₃ · 4H ₂ O) was raised from room temperature to 600 ° C. at a heating rate of 5 ° C./min. Warm and hold at 600 ° C. for 5 hours to prepare Y ₂ O ₃ .

(3) Preparation of Other Carriers CeO ₂ was also prepared from cerium (III) nitrate hexahydrate (Wako, Ce (NO ₃ ) ₃ · 6H ₂ O) by the same preparation method as the Y ₂ O ₃ carrier.
Other carriers (Al ₂ O ₃ (Merck), La ₂ O ₃ (Nacalai Tesque), SiO ₂ (FUJI SILYSIA)) were used as they were.

(4) Preparation of NiO (16) -Cr ₂ O ₃ (4) / MgO catalyst An aqueous solution in which a predetermined amount of Ni (NO ₃ ) ₂ .6H ₂ O and Cr (NO ₃ ) ₃ · 9H ₂ O is dissolved To 1 g of carrier (MgO), Ni was added in an amount of 16 mmol and Cr as 4 mmol, and after standing overnight, it was dried by evaporation to dryness. Thereafter, the temperature was raised from room temperature to 600 ° C. under air circulation, and the catalyst was prepared by holding at 600 ° C. for 5 hours. This is a so-called impregnation supporting method, and hereinafter referred to as “(supported substance) / (support)” when supported by this method.
The numbers in parentheses such as NiO (16) in the catalyst display represent the amount of metal element supported per gram of support in millimoles.

(5) Preparation of NiO (16) -Cr ₂ O ₃ (4) -MgO catalyst Predetermined amounts of Ni (NO ₃ ) ₂ .6H ₂ O, Cr (NO ₃ ) ₃ · 9H ₂ O and Mg (NO ₃ ) the ₂ · 6H ₂ O was dissolved in water and dried by evaporation to dryness. Thereafter, the temperature was raised from room temperature to 600 ° C. under air circulation, and the catalyst was prepared by holding at 600 ° C. for 5 hours. Hereinafter, when prepared by this method, it is expressed as “(supported substance)-(support)”. The numbers in parentheses are the same as in the catalyst preparation by the impregnation support method.
A catalyst prepared by the same method as described above was also prepared except that the calcination temperature was 800 ° C.
In addition, the catalyst of other compositions, such as a comparative example, was prepared by the same method using the water-soluble salt of each component.

(5) Experimental apparatus for evaluation The reaction apparatus shown in FIG. 1 was used as an experimental apparatus for evaluation. However, this reactor is only an experimental device for evaluation, and an apparatus for actually producing a hydrogen-containing gas using this catalyst is not limited to this reactor. It can be changed as appropriate according to the situation.

  In the reaction apparatus of FIG. 1, the reaction tube 2 is a quartz glass tube, and has an inner diameter of 10 mm and a length of 250 mm, for example, and is filled with the partial oxidation catalyst layer 4. The catalyst layer 4 is sandwiched between quartz glass wool from both sides and fixed in the reaction tube 2. An electric furnace 6 is provided for heating the reaction tube 2, and the reaction tube 2 is positioned with respect to the electric furnace 6 so that the reaction tube 2 is accommodated in the electric furnace 6. A quartz glass thermocouple protective tube (not shown) is installed for the catalyst layer 4, and a thermocouple (not shown) is passed through it to contact the catalyst layer 4. The temperature of the catalyst layer 4 is detected by the thermocouple, and energization to the electric furnace 6 is controlled by a temperature controller (not shown) so that the detected temperature becomes a set temperature.

  At one end of the reaction tube 2, a raw material gas supply flow path 8 for supplying methane as a raw material gas for partial oxidation reaction, and a regeneration gas for supplying a mixed gas of oxygen and argon, water vapor or air as an oxygen-containing gas at the time of catalyst regeneration. The supply flow path 10 is connected so that gas can be supplied by being switched by the three-way switching valve 12. Each of the flow paths 8 and 10 includes mass flow controllers 14 and 18 for supplying respective gases at a constant flow rate. On-off valves 16 and 20 are arranged upstream of the respective mass flow controllers 14 and 18.

  The other end of the reaction tube 2 is connected to a gas chromatograph 24 and a mass spectrometer 26 via a three-way valve 22. Although a quadrupole mass spectrometer is used as the mass spectrometer 26, other types of mass spectrometers may be used. By switching the three-way valve 22, the reaction gas from the reaction tube 2 is led to the gas chromatograph 24 or the mass spectrometer 26 and analyzed as appropriate. However, such an arrangement of analyzers is an arrangement for collecting experimental data and is not indispensable for a practical system.

  In addition, when diluting the gas used for the experiment, argon was used as the diluting gas because of restrictions on the use conditions of the analyzer. This is because, when attempting to analyze carbon monoxide with a mass spectrometer, nitrogen having the same mass number as carbon monoxide cannot be used as a diluent gas. And since argon is an inert gas, it has been confirmed that it has no influence on the catalytic reaction.

(6) Hydrogen production reaction from methane using the partial oxidation catalyst of the present invention The produced catalyst was evaluated by a partial oxidation reaction of methane. Note that methane was diluted and introduced with argon, an inert gas, due to restrictions on the sensitivity and resolution of the analyzer, but argon has no effect on the evaluation of catalyst activity.

(7) Regeneration reaction of catalyst of the present invention The catalyst after carrying out hydrogen production reaction by partial oxidation of methane for a certain period of time is oxidized with oxygen gas diluted with argon or air, and again subjected to partial oxidation reaction of methane, It was evaluated that it was completely regenerated by its performance. Further, as shown in FIG. 2 to be described later, it was confirmed that the catalyst of the present invention was regenerated by oxidation also from the result of X-ray diffraction of the catalyst.

  In an actual partial oxidation experiment, 0.5 g of the prepared catalyst was charged into a reaction tube, a mixed gas of argon: methane = 4: 1 was supplied at a flow rate of 25 ml / min, and a flow rate SV = 3,000 ml / g-cat · h ( The temperature of the catalyst was raised to 700 ° C. at a rate of 10 degrees per minute in an environment where SV is flowing at a space velocity), and then held at 700 ° C. for a predetermined time. When the experiment is performed by alternately repeating partial oxidation and catalyst regeneration, the partial oxidation reaction is performed for a predetermined time, and then the gas is switched to a mixed gas of argon: oxygen = 4: 1 at 700 ° C. The catalyst was regenerated by reacting at a space velocity of SV = 3,000 ml / g-cat · h for the same time as the partial oxidation.

The above reaction conditions are experimental conditions for evaluation, and are appropriately changed according to the purpose when actually producing industrially.
Hereinafter, the present invention will be described in more detail with reference to examples.

NiO (16) -Cr ₂ O ₃ (4) -MgO catalyst prepared at a calcination temperature of 600 ° C. (Mg, Ni, and Cr are added so that 16 mmol of NiO and 4 mmol of Cr ₂ O ₃ are contained per 1 g of MgO. Using a catalyst prepared from an aqueous solution dissolved in this manner, repeated experiments of methane partial oxidation reaction-catalyst regeneration were carried out. The reaction and regeneration time was 10 minutes each and repeated 3 times. The reaction temperature and regeneration temperature were 600 ° C for the first time, 700 ° C for the second time, and 800 ° C for the third time. The results are shown in Table 1. In the reaction at 600 ° C., the conversion rate of methane as a raw material was low, but at a temperature of 700 ° C. or higher, a conversion rate of 90% or higher was obtained. Further, in the reactions at 600 ° C. and 700 ° C., the CO selectivity is high, but the CO ₂ selectivity is low, so that it is understood that the partial oxidation reaction for generating synthesis gas (H ₂ + CO) proceeds. Although a higher methane conversion rate is exhibited at 800 ° C., it can be said that the catalyst of the present invention sufficiently performs its function at 700 ° C. because the rate of complete oxidation is increased and carbon deposition is slightly increased. It goes without saying that a lower reaction temperature requires less energy for heating and is industrially advantageous.

  Using the catalyst of Example 1, an experiment was conducted in which a partial oxidation reaction at 700 ° C. and a regeneration reaction at 700 ° C. were repeated 10 times. As shown in Table 2, the methane conversion ratio was maintained at around 90% even after 10 reaction-regeneration cycles, indicating that the catalyst of this example had a long life. The hydrogen selectivity was slightly lower in the first and second rounds, but remained around 90% thereafter.

For the NiO (16) -Cr ₂ O ₃ (4) -MgO catalyst prepared at a calcination temperature of 700 ° C., an experiment was conducted in which a partial oxidation reaction at 700 ° C. and a regeneration reaction at 700 ° C. were repeated 10 times. The results of this experiment are also shown in Table 2. Through 10 repeated experiments, the methane conversion was 90% or more, and the hydrogen selectivity and CO selectivity were both stable and high, indicating that the catalyst was excellent in both activity and life.

For the NiO (16) -Cr ₂ O ₃ (4) -MgO catalyst prepared at a calcination temperature of 800 ° C., an experiment was performed in which the partial oxidation reaction at 700 ° C. and the regeneration reaction at 700 ° C. were repeated 10 times. The results of this experiment are also shown in Table 2. Compared to the case of Example 1, the methane conversion rate was slightly decreased, but the hydrogen selectivity was 87.6% for the first time and exceeded 90% for the second time and thereafter, and the catalyst was excellent in stability. Showed that.

The same catalyst as in Example 1 except that the content of Cr ₂ O ₃ was doubled to 8 mmol, ie, NiO (16) -Cr ₂ O ₃ (8) -MgO catalyst ((16 mmol of NiO per 1 g of MgO) And a catalyst prepared from an aqueous solution in which Mg, Ni and Cr are completely dissolved so as to contain 8 mmol of Cr ₂ O ₃ , repeated experiments of methane partial oxidation reaction-catalyst regeneration were conducted. The regeneration time was 10 minutes each and was repeated 5. The reaction temperature and regeneration temperature were 600 ° C. for the first time, 650 ° C. for the second time, 700 ° C. for the third time, and 750 ° C. for the fourth time. The results were shown in Table 3. The results are shown in Table 3. The catalyst performance is almost the same as that of Example 1, and it can be seen that this increase in Cr ₂ O ₃ does not affect the catalyst performance.

The same catalyst as in Example 4 except that the NiO content was doubled to 32 mmol, that is, NiO (32) -Cr ₂ O ₃ (8) -MgO catalyst ((32 mmol of NiO per 8 g of MgO and 8 mmol) In the same manner as in Example 4, a methane partial oxidation reaction-catalyst regeneration repeated experiment was conducted on a catalyst prepared from an aqueous solution in which Mg, Ni, and Cr were all dissolved so that Cr ₂ O ₃ was contained. The reaction and regeneration time were 10 minutes each and repeated 5 times, the reaction temperature and regeneration temperature were also 600 ° C. for the first time, 650 ° C. for the second time, and 700 ° C. for the third time as in Example 4. The fourth time was 750 ° C. and the fifth time was 800 ° C. The results are shown in Table 3.
Although the methane conversion rate is high as in Example 4, the generation of CO ₂ and H ₂ O increases, so it is considered that the combustion reaction is likely to occur when the NiO content is increased.

For NiO (16) -Cr ₂ O ₃ (4) / MgO catalyst prepared by impregnating and supporting an aqueous solution containing Ni and Cr on an MgO support, the partial oxidation reaction of methane-catalyst regeneration reaction is performed 3 times, 10 minutes each. Repeated experiments were performed. The reaction temperature was 600 ° C for the first time, 700 ° C for the second time, and 800 ° C for the third time. The results are shown in Table 1 together with Example 1. Both the methane conversion rate and the hydrogen selectivity showed the same performance as in Example 1, and an excellent catalyst was obtained by the preparation method of this example. However, it can be said that Example 1 is a more excellent catalyst because the amount of deposited carbon is slightly larger than that of Example 1, and the CO selectivity is low and the ratio of complete oxidation is high.

A NiO (16) -Cr ₂ O ₃ (4) -SiO ₂ catalyst prepared in the same manner as in Example 1 except that silica (SiO ₂ ) was used as a support (16 mmol of NiO per 4 g of SiO ₂ and 4 m Using a catalyst prepared from an aqueous solution in which all of Si, Ni, and Cr were dissolved so as to contain mol Cr ₂ O ₃ , repeated experiments of methane partial oxidation reaction-catalyst regeneration were performed. The reaction and regeneration time was 10 minutes each and repeated 3 times. The reaction temperature was 600 ° C for the first time, 700 ° C for the second time, and 800 ° C for the third time. The results are shown in Table 4. In the reaction at 600 ° C., the conversion rate of methane as a raw material was low, but at a temperature of 700 ° C. or higher, a conversion rate of 90% or higher was obtained. Although a higher methane conversion is exhibited at 800 ° C., it can be said that the catalyst of the present invention exhibits its function sufficiently at 700 ° C. as in Example 1 because the rate of complete oxidation becomes high. Only a small amount of carbon deposition is observed, indicating excellent performance.

A NiO (16) -Cr ₂ O ₃ (4) -Y ₂ O ₃ catalyst (per 1 g of Y ₂ O ₃ ) prepared in the same manner as in Example 1 except that yttria (Y ₂ O ₃ ) was used as the carrier. Using a catalyst prepared from an aqueous solution in which all of Y, Ni, and Cr are dissolved so that 16 mmol of NiO and 4 mmol of Cr ₂ O ₃ are contained, repeated experiments of partial oxidation reaction of methane-catalyst regeneration Carried out. The reaction and regeneration time was 10 minutes each and repeated 3 times. The reaction temperature was 600 ° C for the first time, 700 ° C for the second time, and 800 ° C for the third time. The results are shown in Table 4. In the reaction at 600 ° C., the conversion rate of methane as a raw material was low, but a good conversion rate of 83.4% at 700 ° C. and 93.3% at 800 ° C. was obtained. In particular, in the reaction at 700 ° C., the CO selectivity is high and carbon deposition is suppressed, and it is a catalyst that fully exhibits its function at 700 ° C. as in Example 1.

[Comparative Example 1]
A catalyst similar to Example 1 except that it does not contain Cr ₂ O ₃ , that is, a NiO (16) -MgO catalyst (a catalyst prepared from an aqueous solution in which Mg and Ni are dissolved so as to contain 16 mmol of NiO per 1 g of MgO) ), Repeated experiments of partial oxidation reaction of methane-catalyst regeneration were conducted. The reaction and regeneration time was 10 minutes each and was repeated 4 times. The reaction temperature was 500 ° C for the first time, 600 ° C for the second time, 700 ° C for the third time, and 800 ° C for the fourth time. The results are shown in Table 4. Although the methane conversion increases at 700 ° C. or higher, carbon deposition is large and not suitable for practical use.

  Table 5 shows the results of experiments in which partial oxidation reaction of methane at 700 ° C. and catalyst regeneration were repeated 10 times for 10 minutes each using this catalyst. Even if the reaction-regeneration at 700 ° C. is repeated, the amount of carbon deposition is consistently large and is not suitable as a partial oxidation reaction catalyst.

[Comparative Example 2]
The same catalyst as in Example 1 except that ceria (CeO ₂ ) was used as a support, ie, NiO (16) -Cr ₂ O ₃ (4) -CeO ₂ catalyst (16 mmol NiO and 4 mmol mol per gram CeO ₂ A catalyst prepared from an aqueous solution in which all of Ce, Ni, and Cr were dissolved so as to contain Cr ₂ O ₃ was subjected to repeated experiments of partial oxidation reaction of methane-catalyst regeneration. The reaction and regeneration time was 10 minutes each and repeated 3 times. The reaction temperature was 700 ° C for the first time, 600 ° C for the second time, and 800 ° C for the third time. The results are shown in Table 4. Although the methane conversion rate increases at 700 ° C. or higher, the complete oxidation reaction proceeds because the CO ₂ selectivity is high while the selectivity of hydrogen and CO is low, and MgO and SiO It is clear that the catalyst is not a partial oxidation reaction catalyst such as the catalyst of the present invention using ₂ as a support.

[Comparative Example 3]
NiO (16) -Cr ₂ O ₃ (4) prepared by impregnating and supporting an aqueous solution containing Ni and Cr on a CeO ₂ carrier, except that ceria (CeO ₂ ) was used as the carrier. For the / CeO ₂ catalyst, a partial oxidation reaction of methane-catalyst regeneration reaction was carried out for 10 minutes each at temperatures of 500 ° C., 600 ° C., 700 ° C., and 800 ° C. Although the methane conversion rate increases at 700 ° C. or higher, it is clear that the combustion reaction proceeds because of the large amount of CO ₂ and H ₂ O, and the activity as a partial oxidation catalyst is low.

[Comparative Example 4]
The same catalyst as in Example 1 except that lanthanum oxide (La ₂ O ₃ ) was used as the carrier, ie, NiO (16) -Cr ₂ O ₃ (4) -La ₂ O ₃ catalyst (16 m per gram of La ₂ O ₃ (catalyst prepared from an aqueous solution in which all of La, Ni, and Cr are dissolved so as to contain 4 mol of NiO and 4 mmol of Cr ₂ O ₃ ), a partial oxidation reaction of methane under the same conditions as in Comparative Example 2 Experiments were repeated three times for catalyst regeneration. This result is also shown in Table 4, but the hydrogen selectivity is low but the CO ₂ selectivity is high, which is not suitable as a catalyst for partial oxidation reaction of methane.

[Comparative Example 5]
Similar catalyst except that an alumina (Al ₂ O ₃₎ as carrier as in Example 6, i.e. Al ₂ O ₃ carrier was prepared by impregnation with an aqueous solution containing Ni and Cr NiO (16) -Cr ₂ O _{3 For the} (4) / Al ₂ O ₃ catalyst, a partial oxidation reaction of methane-catalyst regeneration reaction was carried out for 10 minutes each at temperatures of 500 ° C., 600 ° C., 700 ° C., and 800 ° C. Although this result is also shown in Table 4, it can be seen that the methane conversion increases at 700 ° C. or higher, but the CO selectivity is low and the partial oxidation reaction activity is poor.

[Comparative Example 6]
A catalyst similar to that of Example 1 except that CaO was used instead of Cr ₂ O ₃ , that is, a NiO (16) -CaO (4) -MgO catalyst (containing 16 mmol of NiO and 4 mmol of CaO per 1 g of MgO). For example, a catalyst prepared from an aqueous solution in which Mg, Ni, and Ca are completely dissolved) was subjected to partial oxidation reaction of methane-catalyst regeneration reaction at temperatures of 500 ° C, 600 ° C, 700 ° C, and 800 ° C for 10 minutes each. Table 6 shows the results. Although the partial oxidation reaction proceeds at 700 ° C. or higher, the carbon deposition amount is large in this temperature range, which is not suitable as a practical catalyst.

[Comparative Example 7]
The same catalyst as in Example 1 except that Fe ₂ O ₃ was used instead of Cr ₂ O ₃ , that is, NiO (16) -Fe ₂ O ₃ (4) -MgO catalyst (16 mmol of NiO and 4 mmol of MgO per 1 g of MgO). Table 6 shows the results of experiments similar to those of Comparative Example 6 for a catalyst prepared from an aqueous solution in which Mg, Ni, and Fe are all dissolved so that Fe ₂ O ₃ is contained. Since there is much CO ₂ generation at any temperature, it is clear that the complete oxidation reaction is dominant and it does not become a partial oxidation reaction catalyst.

[Comparative Example 8]
The same catalyst as in Example 1 except that Al ₂ O ₃ was used instead of Cr ₂ O ₃ , that is, NiO (16) -Al ₂ O ₃ (4) -MgO catalyst (16 mmol of NiO and 4 mmol of MgO per 1 g of MgO). Table 6 shows the results of experiments similar to those of Comparative Example 6 for a catalyst prepared from an aqueous solution in which Mg, Ni, and Al are all dissolved so that Al ₂ O ₃ is contained. If the reaction temperature is increased to 800 ° C., a high methane conversion rate is obtained and a partial oxidation reaction proceeds. However, since the amount of carbon deposition is large, it is not practical.

[Comparative Example 9]
The same catalyst as in Example 1 except that Nd ₂ O ₃ was used instead of Cr ₂ O ₃ , that is, NiO (16) -Nd ₂ O ₃ (4) -MgO catalyst (16 mmol of NiO and 4 mmol of MgO per 1 g of MgO). Table 6 shows the results of experiments similar to those of Comparative Example 6 for a catalyst prepared from an aqueous solution in which Mg, Ni, and Nd were dissolved so that Nd ₂ O ₃ was contained. As in Comparative Example 8, if the reaction temperature is increased to 800 ° C., a high methane conversion rate is obtained and the partial oxidation reaction proceeds. However, since the amount of carbon deposition is large, it is not practical.

[Comparative Example 10]
The same catalyst as in Example 1 except that Co ₃ O ₄ was used instead of Cr ₂ O ₃ , that is, NiO (16) -Co ₃ O ₄ (4) -MgO catalyst (16 mmol of NiO and 4 mmol of MgO per 1 g of MgO). Table 6 shows the results of experiments similar to those of Comparative Example 6 for a catalyst prepared from an aqueous solution in which Mg, Ni, and Co are all dissolved so that Co ₃ O ₄ is contained. As in Comparative Example 8, if the reaction temperature is increased to 800 ° C., a high methane conversion rate is obtained and the partial oxidation reaction proceeds. However, since the amount of carbon deposition is large, it is not practical.

(Confirmation of catalyst regeneration by X-ray diffraction)
It was confirmed by X-ray diffraction measurement of the catalyst that the lattice oxygen of the catalyst of the present invention was involved in the partial oxidation reaction and could be regenerated. The result of the X-ray diffraction measurement is shown in FIG. The catalyst of Example 1 was used as the catalyst. In the figure, (A) and (B) are different in scale of the vertical axis 10 times.

a) is an X-ray diffraction pattern of the catalyst after preparation. A NiMgO ₂ peak indicated by a symbol “◯” in the figure is recognized, and it can be seen that Ni is present as a composite oxide by reacting with MgO of the carrier. When the vertical scale is enlarged, it can be confirmed that MgCr ₂ O ₄ indicated by the symbol □ in the figure also exists.

The X-ray diffraction patterns after the partial oxidation reaction of methane on this catalyst are (A) b), c) and (B) b). NiMgO ₂ shown by a symbol of ○, in addition to MgCr ₂ O _4, which is indicated by the symbol of □, the peak of the metal Ni indicated by △ are emerging. That is, it is clear that the lattice oxygen of the Ni complex oxide constituting the catalyst was consumed in the partial oxidation reaction of methane, and Ni was reduced.

The X-ray diffraction pattern of the catalyst after repeating the methane partial oxidation reaction-catalyst regeneration reaction 10 times is shown in d) of (A). Only the peak of NiMgO ₂ indicated by ○ was seen, and it was confirmed that the state was returned to the state equivalent to a) of (A) immediately after preparation.
Note that the pattern c) in (B) is an X-ray diffraction pattern of Cr ₂ O ₃ —MgO not containing Ni synthesized for identification of each peak.

(Catalyst regeneration by air)
The experiments presented so far have used oxygen diluted with argon gas for regeneration of the catalyst after being subjected to a partial oxidation reaction. However, if the catalyst regeneration by reoxidation can be performed with air, it is not necessary to install an oxygen supply facility in the apparatus, and the system can be reduced in size and cost, and it is clear that there are significant advantages in practical use. is there. Thus, catalyst regeneration using air was performed using the catalyst of Example 1. The results are shown in Table 7. When air was used as the regeneration gas, the amount of carbon deposition, methane conversion, CO selectivity, and CO ₂ selectivity could not be measured due to the limitations of the experimental apparatus in which the analysis was performed with a mass spectrometer, but the hydrogen selectivity, As far as the lattice oxygen conversion rate and the amount of other products are observed, it is clear that the catalyst regeneration by oxygen diluted with argon gas is the same as the catalyst regeneration by air.

(Example 1 of a hydrogen-containing gas production apparatus)
FIG. 3 schematically shows an embodiment of a hydrogen-containing gas production apparatus using a fixed bed reaction tube fixed so that the partial oxidation catalyst cannot move.
A heating furnace 6a is arranged in the first reaction tube 2a, and a heating furnace 6b is arranged in the second reaction tube 2b. The reaction tubes 2a and 2b and the heating furnaces 6a and 6b are basically the same as those of the evaluation apparatus shown in FIG. The partial oxidation catalyst layer of the present invention is filled in the reaction tubes 2a and 2b.

  A three-way switching valve is provided at one end of one reaction tube 2a with a source gas supply channel 8 for supplying methane and other hydrocarbons as source gas, and a regeneration gas supply channel 10 for supplying air as an oxygen-containing gas during catalyst regeneration. It connects so that gas can be supplied by switching by 12a. One end of the other reaction tube 2b is connected to the source gas supply flow path 8 and the regeneration gas supply flow path 10 so that gas can be supplied by being switched by a three-way switching valve 12b. As shown in FIG. 1, the source gas supply flow path 8 and the regeneration gas supply flow path 10 are each provided with an on-off valve and a mass flow controller.

  The three-way switching valves 12a and 12b are simultaneously switched by the controller 30, and when the raw material gas is supplied to the reaction tube 2a, the regeneration gas is supplied to the reaction tube 2b, and conversely, the raw material gas is supplied to the reaction tube 2b. Is controlled so that the regeneration gas is supplied to the reaction tube 2a.

  The temperatures of the heating furnaces 6a and 6b are also controlled by the controller 30 and adjusted so as to be set to partial oxidation reactions or catalyst regeneration temperatures in the respective reaction tubes 2a and 2b. When the set temperature of the reaction tubes 2a and 2b is not changed between the partial oxidation reaction and the catalyst regeneration, the controller 30 controls the temperature of the reaction tubes 2a and 2b to be constant.

  In this way, by controlling the heating furnaces 6a and 6b and the switching valves 12a and 12b, the catalyst in the other reaction tube is regenerated during the partial oxidation reaction in one reaction tube, and the operation is alternately performed. You can switch to

(Example 2 of a hydrogen-containing gas production apparatus)
FIG. 4 schematically shows an embodiment of a hydrogen-containing gas production apparatus using a moving bed reaction tube in which a partial oxidation catalyst is held in a movable state.

  The reaction tube includes a reaction unit 20 that performs a partial oxidation reaction, and a regeneration unit 22 that performs catalyst regeneration at a location different from the reaction unit 20. The reaction unit 20 and the regeneration unit 22 are each provided with a heating furnace and adjusted so as to have respective set temperatures. The set temperatures of the reaction unit 20 and the regeneration unit 22 may be the same or different.

  A regeneration unit 22 is disposed above the reaction unit 20. A regeneration gas supply passage 24 for supplying air as an oxygen-containing gas for catalyst regeneration is connected to the lower part of the regeneration unit 22, and a gas discharge port 26 is provided at the upper part. The regeneration unit 22 can store the regenerated catalyst, and has an opening at the bottom, and drops the regenerated catalyst from the opening to the reaction unit 20 by a certain amount per unit time.

  A raw material gas supply passage 28 for supplying methane and other hydrocarbons as a raw material gas is connected to the upper part of the reaction unit 20, and a partial oxidation reaction is performed in contact with a fluidized catalyst in the reaction unit 20. An opening is provided at the bottom of the reaction unit 20, and a catalyst receiving unit 32 is provided at the bottom of the reaction unit 20, and a used catalyst that has dropped from the opening at the bottom of the reaction unit 20 is received by the catalyst receiving unit 32.

  A transport path 34 is provided for transporting the catalyst received by the catalyst receiver 32 to the regeneration unit 22. The transport path 34 is a lifter that transports the catalyst by pushing it up with a belt or a screw in the flow path.

  The reaction gas that has undergone the partial oxidation reaction in the reaction section 20 is sent to the regeneration section 22 through the flow path of the transport path 34 and is taken out together with the used regeneration gas from the gas outlet 26 of the regeneration section 22.

  In this hydrogen-containing gas production apparatus, the partial oxidation reaction and the catalyst regeneration are executed in parallel at different locations, and the catalyst circulates between the reaction unit 20 and the regeneration unit 22, and therefore can be operated continuously.

  The partial oxidation catalyst of the present invention and the production method and apparatus using the catalyst can be used to produce a hydrogen-containing mixed gas that is a raw material for producing hydrogen or synthesis gas. In particular, in the catalyst of the present invention, since the lattice oxygen of the oxide constituting the catalyst itself is used in the partial oxidation reaction, and oxygen in the air can be used for catalyst regeneration after the reaction, it is extremely compact and inexpensive. A mixed gas production apparatus can be constructed. Such a hydrogen-containing mixed gas production apparatus is suitable, for example, as a fuel supply apparatus for a fuel cell as a distributed power source. Incorporating two series of catalyst reaction tubes so that one is regenerated while the other is being used for the reaction, or using the catalyst reaction tube as a moving bed to circulate the catalyst between the reaction section and the regeneration section Thus, continuous operation becomes possible. For example, in a system that uses a hydrogen-containing mixed gas during the day and wants to stop during the night, only one series of catalyst is used, a partial oxidation reaction is performed during operation, and the catalyst is regenerated during the night out. A compact device configuration is possible.

It is a schematic block diagram which shows the reaction apparatus for evaluating a catalyst. It is a figure which shows the X-ray-diffraction pattern before and behind the partial oxidation reaction of the catalyst of Example 1, and after reproduction | regeneration. It is a schematic block diagram which shows one Example of a hydrogen containing gas manufacturing apparatus. It is a schematic block diagram which shows the other Example of the hydrogen containing gas manufacturing apparatus.

Explanation of symbols

2, 2a, 2b Reaction tube 4 Partial oxidation catalyst layer 6, 6a, 6b Electric furnace 8 Material gas supply flow path 10 Regeneration gas supply flow path 12, 12a, 12b Three-way switching valve 20 Reaction section 22 Regeneration section 30 Controller 32 Catalyst receiver Part 34 Conveyance path

Claims (12)

In a partial oxidation catalyst that partially oxidizes hydrocarbons to produce a mixed gas containing hydrogen and carbon monoxide,
A partial oxidation catalyst comprising at least a catalyst component and a support, wherein the catalyst component contains only nickel oxide and chromium oxide.   The partial oxidation catalyst according to claim 1, wherein the support contains an oxide of magnesium.   2. The partial oxidation catalyst according to claim 1, wherein the support contains an oxide of silicon.   The partial oxidation catalyst of claim 1, wherein the support comprises an oxide of yttrium. A step of preparing only nickel and chromium, and magnesium as the metal element serving as a carrier, a mixed solution prepared by dissolving a salt containing the metal elements of silicon or yttrium as a metal element as a catalyst component,
A drying step of removing the solvent of the solution;
A firing step of firing in an oxidizing atmosphere after the drying step;
The catalyst manufacturing method which manufactures the partial oxidation catalyst of Claim 1 containing this. Adding a solution in which a salt containing only nickel and chromium metal elements is dissolved to magnesium oxide (MgO), silica (SiO ₂ ) or yttrium oxide (Y ₂ O ₃ ) as a carrier;
Thereafter, a drying step of removing the solvent of the solution;
A firing step of firing in an oxidizing atmosphere after the drying step;
The catalyst manufacturing method which manufactures the partial oxidation catalyst of Claim 1 containing this. A metal in the partial oxidation catalyst is brought into contact with the partial oxidation catalyst according to any one of claims 1 to 4 under heating without supplying an oxygen-containing gas as an oxidant. A partial oxidation step of partially oxidizing the hydrocarbon with lattice oxygen constituting the oxide to generate a mixed gas containing hydrogen and carbon monoxide;
A regeneration step of regenerating the partial oxidation catalyst by contacting the partial oxidation catalyst that has undergone the partial oxidation step with an oxygen-containing gas under heating;
A method for producing a hydrogen-containing gas comprising:   The method for producing a hydrogen-containing gas according to claim 7, wherein water vapor is used as the oxygen-containing gas.   The method for producing a hydrogen-containing gas according to claim 7, wherein air is used as the oxygen-containing gas. A reaction tube in which the partial oxidation catalyst according to any one of claims 1 to 4 is held,
A heating furnace for heating the catalyst;
A raw material gas supply channel for sending a raw material gas containing hydrocarbons to the reaction tube and contacting the catalyst;
A regeneration gas supply flow path for sending an oxygen-containing gas used for catalyst regeneration to the reaction tube and bringing it into contact with the partial oxidation catalyst,
In the reaction tube, in the absence of an oxygen-containing gas as an oxidant, the hydrocarbon in the raw material gas is partially oxidized by lattice oxygen constituting the metal oxide in the partial oxidation catalyst, and is oxidized with hydrogen. An apparatus for producing a hydrogen-containing gas, which generates a mixed gas containing carbon and regenerates the partial oxidation catalyst with an oxygen-containing gas from the regeneration gas supply flow path in a state where the source gas does not exist. The reaction tube is a fixed bed reaction tube fixed so that the partial oxidation catalyst cannot move,
Two sets of the reaction tube and the heating furnace are provided,
The source gas supply channel and the regeneration gas supply channel are connected to both reaction tubes via a switching valve,
By controlling the heating furnace and the switching valve, the catalyst in the other reaction tube is regenerated during the partial oxidation reaction in one reaction tube, and the operation can be switched alternately. The hydrogen-containing gas production apparatus according to claim 10. The reaction tube is a moving bed reaction tube held in a state where the catalyst is movable, and the reaction tube performs a partial oxidation reaction and a regeneration for performing catalyst regeneration in a place different from the reaction unit. Department and
A transport path for transporting the catalyst between the reaction unit and the regeneration unit is provided;
The hydrogen-containing gas production apparatus according to claim 10, wherein the source gas supply flow path is connected to the reaction section, and the regeneration gas supply flow path is connected to the regeneration section.

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