JP5324265B2 - 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.

  Conventionally, hydrogen production from fossil fuels such as natural gas has been carried out on a large scale mainly by the steam reforming method. However, since the steam reforming itself is an endothermic reaction, it requires a large amount of energy input. There were problems such as releasing a large amount of carbon dioxide, a living organism, into 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 published a novel catalyst using ferric oxide as a catalytic active component as a partial oxidation catalyst that has improved the above problems (Non-patent Document 7). According to the 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 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 K.L. Tan, Catalysis Letter 59 (1999) 129-135 S. Wang and G. Q. 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.

  The second object of the present invention is to provide a method for producing a hydrogen-containing gas using the catalyst.

  A third 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 conducted a partial oxidation reaction of hydrocarbons such as methane using the lattice oxygen of the catalyst itself, using a catalyst containing an oxide of iron and chromium, and the product It was confirmed that the hydrogen selectivity in the catalyst was high and that the catalyst was easily regenerated and could be regenerated with oxygen, air, etc., and the present invention was completed.

  That is, the first embodiment of the present invention is a binary catalyst made of an oxide of iron and chromium.

  When this binary catalyst was examined in detail, it was found that there was much carbon deposition. However, since this catalyst is accompanied by a regeneration step in which the catalyst is regenerated with oxygen, air or the like, the produced carbon is removed as carbon dioxide gas during the regeneration step. For this reason, carbon deposition is not a significant drawback in this catalyst. Nevertheless, in order to lengthen the use time until the regeneration step, it is preferable that the carbon deposition is small. From such a viewpoint, as a result of studying measures for suppressing carbon deposition, it was found that it is effective to add magnesium as the third catalyst component.

  Therefore, the second embodiment of the present invention is a ternary oxide catalyst containing magnesium in addition to iron and chromium. By setting it as such a ternary catalyst, carbon deposition can be suppressed rather than the binary catalyst which consists of an oxide of iron and chromium of the first form.

  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 a catalyst containing an oxide of iron and chromium, or further containing an oxide of magnesium.

  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.

  In addition to the oxide of iron and chromium or the oxide of iron, chromium and magnesium, in order to form the catalyst of the present invention, for example, for the purpose of increasing the specific surface area, it contains a so-called carrier component. Is fine. As the component of the support, various oxides used for ordinary catalysts can be used.

  In the method for producing a hydrogen-containing gas of the present invention, a raw material gas containing hydrocarbon is brought into contact with the partial oxidation catalyst of the present invention under heating, and the hydrocarbon is partially oxidized by lattice oxygen constituting the metal oxide in the partial oxidation catalyst. A partial oxidation step for generating a mixed gas containing hydrogen and carbon monoxide, and a regeneration step for 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. Yes.

  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, but oxygen gas may be used when oxygen gas can be easily procured at the location where the catalyst is used.

  Even if pure oxygen gas is not used, it can be said that it is a remarkable effect that a mixed gas containing hydrogen or a synthesis gas containing no nitrogen can be produced from hydrocarbon gas using air. That is, if an attempt is made to produce a synthesis gas by partially oxidizing hydrocarbons with another catalyst that does not use oxygen of the catalyst itself, an oxygen-containing gas is required as a reaction gas. If air is used as a reaction gas instead of pure oxygen gas, a large amount of nitrogen is mixed in the generated synthesis gas. However, even if air is used in place of pure oxygen gas in the catalyst of the present invention, air is only used in the regeneration process of the catalyst. In the partial oxidation reaction process, oxygen-containing gas is not required and oxygen in the catalyst is not used. Is used, nitrogen is not mixed into the generated synthesis gas.

  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. A raw material gas supply channel, and a regeneration gas supply channel for sending an oxygen-containing gas used for catalyst regeneration to the reaction tube to contact the catalyst, and the raw material gas by lattice oxygen constituting oxides in the catalyst in the reaction tube The hydrocarbon is partially oxidized to produce a mixed gas containing hydrogen and carbon monoxide.

  If two catalyst reaction tubes are used, it is possible to regenerate the other catalyst during one partial oxidation reaction, thereby realizing a continuous hydrogen-containing gas production apparatus. 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.

  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, since methane is a main component of natural gas, methane or natural gas is most preferable from the viewpoint of low-cost hydrogen-containing gas production.

  The partial oxidation catalyst of the present invention is a mixed gas containing hydrogen and carbon monoxide by a partial oxidation method using oxygen of the catalyst itself without the need to connect an oxygen supply gas line or an oxygen cylinder for partial oxidation reaction. The catalyst can be regenerated with air or the like. 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.

  The method and apparatus for producing a hydrogen-containing gas using the partial oxidation catalyst of the present invention can be used to produce a hydrogen-containing mixed gas that is a raw material for producing hydrogen or synthesis gas. In particular, the catalyst of the present invention used therein utilizes the lattice oxygen of the oxide constituting the catalyst itself in the partial oxidation reaction, and the catalyst after the reaction is regenerated by oxidation in the air or the like, so that it is extremely compact and inexpensive. An apparatus for producing a hydrogen-containing mixed gas 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 2, 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.

  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 catalyst of the present invention When preparing a binary catalyst composed of iron and chromium, predetermined amounts of iron nitrate [Fe (H ₂ O) ₆ ] (NO ₃ ) and chromium nitrate Cr (NO ₃ ) ₃ · 9H ₂ O-aqueous were combined and dried by evaporation to dryness after standing overnight. Then, it heated up to 800 degreeC under air circulation, and baked to make the catalyst.

When preparing a ternary catalyst comprising iron, magnesium and chromium, a predetermined amount of iron nitrate [Fe (H ₂ O) ₆ ] (NO ₃ ), magnesium nitrate (Mg (NO ₃ ) ₂ .6H ₂ O) And an aqueous solution of chromium nitrate Cr (NO ₃ ) ₃ .9H ₂ O were mixed and left to stand overnight to dry by evaporation to dryness. Then, it heated up to 800 degreeC under air circulation, and baked to make the catalyst.

(2) 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.

(3) 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.

(4) Regeneration reaction of the catalyst of the present invention The catalyst after carrying out the 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 750 to 800 ° C. at a rate of 10 ° C. per minute in an environment where SV is flowing at a space velocity), and then held at that temperature for a predetermined time. When the experiment is performed by alternately repeating partial oxidation and catalyst regeneration, after performing the partial oxidation reaction for a predetermined time, the gas is switched to a mixed gas of argon: oxygen = 4: 1 at the same temperature, and 25 ml / 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. In addition, since the catalyst of Example 1 does not contain magnesium, it is not included in the present invention. Example 1 should be interpreted as a reference example. The numbers in parentheses such as Fe (16) in the following catalyst notation represent the amount of metal element contained in units of millimolar (mmol) based on 1 g of Cr ₂ O ₃ in the catalyst. is there.

As a binary catalyst composed of an oxide of iron and chromium, Fe (16) -Cr ₂ O ₃ catalyst (containing 16 mmol of Fe per 1 g of Cr ₂ O ₃ ) to Fe (32) -Cr ₂ O ₃ catalyst A catalyst was prepared in which the Fe content was changed in the range of (containing 32 mmol of Fe per 1 g of Cr ₂ O ₃ ). These catalysts were prepared at a calcination temperature of 800 ° C. by the above-mentioned method from an aqueous solution in which all of Fe and Cr nitrates were dissolved.
Using these catalysts, methane partial oxidation reaction-one catalyst regeneration was carried out. The reaction and regeneration time is 10 minutes each, and the reaction temperature is 800 ° C. The results are shown in Tables 1 and 2. For the catalysts shown in Table 1, partial oxidation reaction and one catalyst regeneration were repeated three times. Table 2 shows a comparison between a catalyst containing only Fe and a case where the metal combined with Fe is a metal other than Cr.

From the Fe (16) -Cr ₂ O ₃ catalyst to the Fe (32) -Cr ₂ O ₃ catalyst, a methane conversion rate of approximately 50% or more and a lattice oxygen conversion rate of approximately 30% were obtained. The CO selectivity is not so high and the amount of carbon deposition is large, but the H ₂ selectivity is high. Since the CO ₂ selectivity is low, it can be seen that the partial oxidation reaction for generating synthesis gas (H ₂ + CO) proceeds. The precipitated carbon is removed in the regeneration process.

From the results of Table 2, it can be seen that the Fe-only catalyst has a high CO ₂ selectivity and complete oxidation is the main reaction. In the binary catalyst of Fe and another metal, complete oxidation is the main reaction in the catalyst using Ni or Co instead of Cr. Further, although the binary catalyst of Fe and Al is also partially oxidized, it can be seen that the catalytic activity is low because the conversion rate of methane is low.

Thus, in the binary catalyst containing Fe as the partial oxidation catalyst, the combination of Fe and Cr is most preferable, and the content of Fe per 1 g of Cr ₂ O ₃ is in the range of at least 16 to 32 mmol. Shows good results.

  Using the catalyst of Example 1, an experiment was performed in which a partial oxidation reaction at 800 ° C. and a regeneration reaction at 800 ° C. were repeated three times. As shown in Table 1, it was confirmed that the reaction proceeded stably even when the reaction-regeneration was repeated three times.

Fe (16) -Mg (3) -Cr ₂ O ₃ catalyst prepared at a calcining temperature of 800 ° C. (Fe, Mg and Cr nitrates were added so that 16 mmol of Fe and 3 mmol of MgO were contained per 1 g of Cr ₂ O _3. Using a catalyst prepared from a completely dissolved aqueous solution, partial oxidation reaction of methane and one catalyst regeneration were carried out. The reaction and regeneration time is 10 minutes each, and the reaction temperature is 800 ° C. The results are shown in Tables 3 and 4.

A methane conversion of 52.9% and lattice oxygen conversion of 46.8% were obtained. The one CO selectivity is high, since the CO ₂ selectivity is low, it can be seen that the partial oxidation reaction to produce synthesis gas (H ₂ + CO) is in progress.

  Using the catalyst of Example 2, an experiment was performed in which a partial oxidation reaction at 800 ° C. and a regeneration reaction at 800 ° C. were repeated three times. As shown in Table 4, it was confirmed that the reaction proceeded stably even after repeating one reaction and three regenerations.

Fe (12) -Mg (3) -Cr ₂ O ₃ catalyst prepared at a calcination temperature of 800 ° C. (Fe, Mg, Cr nitrates were added so that 12 mmol of Fe and 3 mmol of MgO were contained per 1 g of Cr ₂ O _3. For all the catalysts prepared from the dissolved aqueous solution, an experiment was conducted in which a partial oxidation reaction at 800 ° C. and a regeneration reaction at 800 ° C. were repeated three times. The results of this experiment are also shown in Table 4.
Through three repeated experiments, the methane conversion was over 70%, and the hydrogen selectivity and CO selectivity were both stable and high, indicating that the catalyst was excellent in both activity and life. However, compared with Example 2, there is a little more carbon deposition.

Fe (8) -Mg (3) -Cr ₂ O ₃ catalyst prepared at a firing temperature of 800 ° C. (Fe, Mg and Cr nitrates were added so that 8 mmol of Fe and 3 mmol of MgO per 1 g of Cr ₂ O ₃ were contained. For all the catalysts prepared from the dissolved aqueous solution, an experiment was conducted in which a partial oxidation reaction at 800 ° C. and a regeneration reaction at 800 ° C. were repeated three times. The results of this experiment are also shown in Table 4. Through three repeated experiments, both the methane conversion rate and the lattice oxygen conversion rate are high, and both the hydrogen selectivity and the CO selectivity are stable and high. However, there is more carbon deposition than in Examples 2 and 3. As a result.

Fe (32) -Mg (3) -Cr ₂ O ₃ catalyst prepared at a calcination temperature of 800 ° C. (Fe, Mg and Cr nitrates were added so that 32 mmol of Fe and 3 mmol of MgO were contained per 1 g of Cr ₂ O _3. For all the catalysts prepared from the dissolved aqueous solution, an experiment was conducted in which a partial oxidation reaction at 800 ° C. and a regeneration reaction at 800 ° C. were repeated three times. The results of this experiment are also shown in Table 4. Compared with Examples 2 and 3, carbon deposition is suppressed to a slight level, but the methane conversion rate and lattice oxygen conversion rate are reduced, hydrogen generation is reduced, and CO ₂ generation is increased.

Fe (48) -Mg (3) -Cr ₂ O ₃ catalyst (from an aqueous solution in which all nitrates of Fe, Mg, and Cr are dissolved so that 48 mmol of Fe and 3 mmol of MgO are contained per 1 g of Cr ₂ O ₃ For the prepared catalyst), an experiment was conducted in which a partial oxidation reaction at 800 ° C. and a regeneration reaction at 800 ° C. were repeated three times. The results of this experiment are also shown in Table 4. Compared with Examples 2 and 3, carbon deposition is suppressed to a slight level, but the methane conversion rate and lattice oxygen conversion rate are reduced, hydrogen generation is reduced, and CO ₂ generation is increased.

  The catalysts of Examples 7 to 9 were prepared by changing the Mg content with respect to the catalyst of Example 3.

In Example 7, the Mg content was increased from 3 mmol of Example 3 to 4 mmol. Fe (12) -Mg (4) -Cr ₂ O ₃ catalyst prepared at a firing temperature of 800 ° C. (Fe, Mg and Cr nitrates were added so that 12 mmol of Fe and 4 mmol of MgO were contained per 1 g of Cr ₂ O _3. For all the catalysts prepared from the dissolved aqueous solution, an experiment was conducted in which a partial oxidation reaction at 800 ° C. and a regeneration reaction at 800 ° C. were repeated three times. The results are shown in Table 5. Compared to Example 3 having the same iron content, the methane conversion rate and the lattice oxygen conversion rate are comparable, the amount of carbon deposition is small, and the hydrogen and CO selectivity are high.

In Example 8, the Mg content was increased from 3 mmol of Example 3 to 5 mmol. Fe (12) -Mg (5) -Cr ₂ O ₃ catalyst prepared at a firing temperature of 800 ° C. (Fe, Mg and Cr nitrates were added so that 12 mmol of Fe and 5 mmol of MgO were contained per 1 g of Cr ₂ O _3. For all the catalysts prepared from the dissolved aqueous solution, an experiment was conducted in which a partial oxidation reaction at 800 ° C. and a regeneration reaction at 800 ° C. were repeated three times. The results are shown in Table 5. The same tendency as in Example 7 shows good results.

In Example 9, the Mg content was increased from 3 mmol of Example 3 to 6 mmol. Fe (12) -Mg (6) -Cr ₂ O ₃ catalyst prepared at a calcination temperature of 800 ° C. (Fe, Mg and Cr nitrates were added so that 12 mmol of Fe and 6 mmol of MgO were contained per 1 g of Cr ₂ O _3. For all the catalysts prepared from the dissolved aqueous solution, an experiment was conducted in which a partial oxidation reaction at 800 ° C. and a regeneration reaction at 800 ° C. were repeated three times. The results are shown in Table 5. Although suppression of carbon deposition, hydrogen selectivity, and CO selectivity are good, the methane conversion is slightly inferior to Examples 3, 7, and 8.

  For Examples 3, 7, 8, and 9, the experiment was repeated three times: partial oxidation reaction-regeneration reaction at 750 ° C. The results are shown in Table 6.

  Even when any of the catalysts of Examples 3, 7, 8, and 9 was used, the amount of carbon deposition decreased, and it became clear that the catalyst of the present invention was more suitable for the reaction at 750 ° C. than 800 ° C. It was. Lowering the reaction temperature is preferable because it results in a reduction in fuel costs for system operation. The reason why the amount of carbon deposition increased in the reaction at 800 ° C. compared to the reaction at 750 ° C. is considered to be due to the decomposition reaction of methane as a side reaction.

Table 7 shows the results of repeating the partial oxidation reaction and regeneration reaction 20 times at 750 ° C. using the Fe (12) -Mg (4) -Cr ₂ O ₃ catalyst of Example 7. Even in 20 repeated experiments, the partial oxidation reaction activity appeared stably, and it was confirmed that the catalyst of the present invention has a long life.

Comparative Example 1

The same catalyst as in Example 2 except that 3 mmol of Ca was used instead of Mg, that is, Fe (16) -Ca (3) -Cr ₂ O ₃ catalyst (16 mmol of Fe and 3 mmol of CaO per 1 g of Cr ₂ O ₃ (Catalyst prepared from an aqueous solution in which all nitrates of Fe, Ca, and Cr were dissolved so as to contain N), a partial oxidation reaction of methane at 800 ° C. and a catalyst regeneration experiment were conducted. The reaction and regeneration time was 10 minutes each. The results are shown in Table 3. Compared to Example 2, the methane conversion rate and the lattice oxygen conversion rate are low, and more CO _{2 is} generated, which is not suitable for practical use.

Comparative Example 2

The same catalyst as in Example 2 except that 3 mmol of Sr was used instead of Mg, that is, Fe (16) -Sr (3) -Cr ₂ O ₃ catalyst (16 mmol of Fe and 3 mmol of SrO per 1 g of Cr ₂ O ₃ (Catalyst prepared from an aqueous solution in which all nitrates of Fe, Sr, and Cr were dissolved so as to contain), a partial oxidation reaction of methane at 800 ° C. and a catalyst regeneration experiment were conducted. The reaction and regeneration time was 10 minutes each. The results are shown in Table 3. Compared to Example 2, the methane conversion rate and the lattice oxygen conversion rate are low, and the amount of CO ₂ generated is somewhat high, which is not suitable for practical use.

(Confirmation of catalyst regeneration by X-ray diffraction)
Among the catalyst components of the present invention, the origin of lattice oxygen involved in the partial oxidation reaction was confirmed by X-ray diffraction measurement. The result of the X-ray diffraction measurement is shown in FIG. The catalyst of Example 3 was used as the catalyst.
c) is an X-ray diffraction pattern of the catalyst before the partial oxidation reaction. In the figure, the peak of Mg and Cr composite oxide MgCr ₂ O ₄ indicated by the symbol ● and of Cr and Fe indicated by an asterisk. A peak of the composite oxide Cr _l.3 Fe _0.7 O ₄ was observed. d) is an X-ray diffraction pattern of the catalyst after the reaction with methane, and a peak of FeCr ₂ O ₄ and metal Fe in which the composite oxide of Cr and Fe is oxidized appears in the composite oxide of Cr and Fe. It was suggested that oxygen near the iron atom contributed to the reaction.
An equivalent spectrum was obtained after one reoxidation and after three reaction-reoxidation cycles, confirming that the catalyst of the present invention was stably regenerated.

(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.

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 (6)

In a partial oxidation catalyst that partially oxidizes hydrocarbons to produce a mixed gas containing hydrogen and carbon monoxide,
A partial oxidation catalyst comprising an iron oxide and a chromium oxide, and further comprising a magnesium oxide. A raw material gas containing a hydrocarbon is brought into contact with the partial oxidation catalyst according to claim 1 under heating, without supplying oxygen-containing gas as oxidizing agent, lattice oxygen constituting the metal oxide of the partial oxidation catalyst A partial oxidation step in which the hydrocarbon is partially oxidized to produce 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 2 , wherein air is used as the oxygen-containing gas. A reaction tube in which the partial oxidation catalyst according to claim 1 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 4 . 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 4 , wherein the source gas supply channel is connected to the reaction unit, and the regeneration gas supply channel is connected to the regeneration unit.

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