JP4514419B2 - Hydrocarbon partial oxidation catalyst, method for producing the same, and method for producing hydrogen-containing gas - Google Patents

Description

  The present invention relates to a hydrocarbon partial oxidation catalyst, a method for producing the same, and a method for producing a hydrogen-containing gas, and more particularly, a catalyst suitable for producing a hydrogen-containing gas by partially oxidizing hydrocarbons, a method for producing the same, and The present invention relates to a method for efficiently producing a hydrogen-containing gas using the same.

  A hydrogen-containing gas mainly composed of hydrogen and carbon monoxide is widely used as a reducing gas and a raw material for various chemical products in addition to the production of hydrogen gas. Recently, practical research has been conducted as a fuel for fuel cells. As a method for producing a hydrogen-containing gas by reforming a hydrocarbon, a hydrocarbon partial oxidation method, a steam reforming method, or an autothermal catalytic steam reforming method combining partial oxidation and steam reforming (autothermal reforming). The forming method) is known.

The partial oxidation method of hydrocarbon is a method in which a hydrocarbon is partially oxidized in the presence of a catalyst to produce a hydrogen-containing gas. For example, when the hydrocarbon is methane, it can be expressed by the following formula. CH ₄ + 1 / 2O ₂ → CO + 2H ₂
For example, the following catalysts have been proposed as catalysts used for partial oxidation of hydrocarbons.

  Patent Document 1 discloses a partial oxidation catalyst in which a coating layer is formed on an active alumina containing an oxide such as lanthanum or cerium as a stabilizer on a monolith support, and platinum and palladium are contained as catalyst components. Proposed.

  Patent Document 2 proposes a partial oxidation catalyst in which a noble metal, nickel, chromium, cobalt, cerium, or lanthanum is supported on a honeycomb-shaped carrier as a catalyst component.

  Patent Document 3 proposes a partial oxidation catalyst in which rhodium is supported on a refractory oxide containing cerium and zirconium, more specifically, a refractory inorganic oxide support made of a mixture of cerium oxide and zirconium oxide. ing. This partial oxidation catalyst is such that when a raw material gas composed of methane and air is subjected to a partial oxidation reaction without adding water vapor, the conversion rate of methane remains at a low level of about 45%.

  Patent Document 4 discloses a catalyst for reforming a lower hydrocarbon fuel by partial oxidation reaction of a raw material gas to which oxygen (or air) and, if necessary, water vapor is added, and is about 100 μm on a honeycomb support. A catalyst in which alumina is coated and a platinum group element is supported thereon is disclosed. In the case of this catalyst, it is necessary to carry 5 to 20 g of platinum group element per 1 L (liter) of the honeycomb support.

  Patent Document 5 discloses a catalyst for use in a self-heating catalytic steam reforming method of a raw material gas composed of hydrocarbon, oxygen, and water or water vapor, and includes aluminum oxide, silicon dioxide, titanium dioxide, or a mixed oxidation thereof. And a catalyst obtained by coating a support such as a ceramic honeycomb with a catalyst component in which at least one platinum group element is contained in an oxide carrier selected from the group consisting of zeolite and zeolite.

JP 59-97501 A

JP-A-1-145301 Japanese translation of PCT publication No. 2002-507535 (refer to claim 10, paragraph 0019) JP-A-7-187605 Japanese Patent Laid-Open No. 2002-12408

As a result of intensive studies on catalysts for producing a hydrogen-containing gas by partially oxidizing hydrocarbons, the inventors have found that the prior art has the following problems.
(1) In the case of partial oxidation of methane or natural gas, which are widely used as hydrocarbons, in order to obtain a high methane conversion rate, it is said that a partial oxidation reaction should be performed at a high temperature of 800 ° C. or higher. Since the catalyst layer is significantly subjected to a thermal load due to the reaction heat during the partial oxidation reaction, the catalytic activity decreases with time.
(2) A carbon generation reaction (side reaction) occurs with the partial oxidation reaction, and the generated precipitated carbon reduces the catalytic activity. In order to prevent such carbon deposition, water vapor may be added to the raw material gas. However, the addition of water vapor causes a problem of an increase in manufacturing cost.
(3) In the case of natural gas, a catalyst poison such as a sulfur content is inevitably contained in the raw material gas, so that the catalyst is poisoned and the catalytic activity decreases with time. In order to prevent such catalyst poisoning, it is conceivable that natural gas is treated in advance with a desulfurizer, etc., and the catalyst poison is removed before performing a partial oxidation reaction. If the apparatus is provided, the configuration of the entire partial oxidation reaction system becomes complicated, and problems such as an increase in maintenance costs arise.

  Thus, one of the objects of the present invention is to provide a catalyst for partial oxidation of hydrocarbons (hereinafter sometimes simply referred to as “partial oxidation catalyst”) having high activity and excellent durability. is there.

  Another object of the present invention is to provide a method for producing the partial oxidation catalyst.

  Another object of the present invention is to provide a method for producing a hydrogen-containing gas by partially oxidizing hydrocarbons using the partial oxidation catalyst.

As a result of studies by the inventors, it has been found that the above object can be achieved by the following invention.
(1) A hydrocarbon partial oxidation catalyst comprising a monolithic carrier carrying a catalyst component containing (A) a platinum group element, (B) a zirconium-cerium composite oxide and (C) a refractory inorganic oxide. In the zirconium-cerium composite oxide of (B), the white metal element of (A) is supported on a part or all of the refractory inorganic oxide of (C) in an amount of 0.4 to 40% by mass. ratio, zirconium oxide and zirconium and cerium _(ZrO 2): as cerium oxide _(CeO 2) (mass ratio), 100: 2-100: 100 der is, the zirconium - cerium composite oxide further yttrium A sulfur poisoning-resistant hydrocarbon partial oxidation catalyst characterized by containing 0.1 to 15% by mass as an oxide based on the total mass of component (B) .
(2) A hydrogen-containing gas is produced by bringing a source gas containing sulfur as a hydrocarbon, oxygen, and catalyst poison into contact with the sulfur-toxic poisoned hydrocarbon partial oxidation catalyst described in (1) above to partially oxidize the hydrocarbon. A method for producing a hydrogen-containing gas.

  The partial oxidation catalyst of the present invention is highly active and excellent in durability. More specifically, the catalyst for partial oxidation of the present invention is suppressed in deterioration of catalytic activity even at high temperatures, is also suppressed in carbon deposition, and is excellent in poisoning resistance. Thus, by using the partial oxidation catalyst of the present invention, the production of a hydrogen-containing gas by partial oxidation of hydrocarbons can be carried out stably in a high yield and for a long time.

  Further, by using the partial oxidation catalyst of the present invention, it is possible to perform partial oxidation of hydrocarbons at a high conversion rate without adding water vapor to the raw material gas. Of course, water vapor may be added to the raw material gas, and by adjusting the mixing ratio of hydrocarbon, oxygen and water vapor, for example, adjustment of the heat balance of the reaction system, composition ratio of hydrogen and carbon monoxide in the produced gas Or the desired hydrocarbon conversion can be achieved.

  In addition, since the partial oxidation catalyst of the present invention has excellent durability against a catalyst poison such as a sulfur content, even if a raw material gas containing a sulfur content is used as it is, Deterioration is suppressed and the partial oxidation reaction can be carried out stably over a long period of time. For this reason, according to the present invention, it is not necessary to provide a catalyst poison removing device such as a desulfurization device, and inexpensive natural gas can be used as a raw material gas as it is, so that the manufacturing cost can be reduced.

  The “monolith carrier” of the present invention is not particularly limited, and any monolith carrier generally known to be used for the preparation of a supported catalyst carrying a catalyst component can be used.

  As the material of the monolith support, a material excellent in heat resistance strength, dust resistance and the like is preferable from the viewpoint of maintaining the shape of the support even at a high temperature during the partial oxidation reaction. For example, cordierite, mullite, α-alumina An oxide such as zirconia, titania, alumina silicate, magnesium silicate, or a heat-resistant alloy such as silicate, stainless steel, or Fe—Cr—Al alloy is preferably used. These may be used alone or in combination of two or more as monolithic carriers. Among these, a monolith carrier mainly composed of cordierite (50% by mass or more) having high heat resistance and excellent heat shock resistance is preferably used.

  The monolithic carrier has holes (cells) penetrating in the parallel direction, but the shape of the holes may be circular or any shape such as a polygon such as a triangle, quadrangle, hexagon, etc. The size can also be determined as appropriate.

  There is no particular limitation on the cell density of the monolithic carrier, and 150 to 600 cells / square centimeter, preferably 250 to 600 cells / square centimeter is preferable in order to increase the contact efficiency with the source gas. If the cell density is too high, individual cells may become small and clogging may occur, and if the cell density is too low, the contact area may be reduced and sufficient catalyst efficiency may not be obtained.

  The monolithic carrier has advantages such as excellent low-pressure loss and dust resistance and easy handling compared to other shaped carriers such as pellet carriers and spherical carriers such as spherical carriers. Have. In addition, the monolithic carrier can be easily manufactured by a known method such as casting molding, press molding, extrusion molding, or sheet molding using the materials described above.

  The catalyst for partial oxidation of the present invention comprises (A) a white metal element, (B) a zirconium-cerium composite oxide, and (C) a refractory inorganic oxide (hereinafter referred to as “component (A)”), respectively. , "Component (B)" and "component (C)").

  Representative examples of the platinum group element of component (A) include platinum, rhodium, palladium, ruthenium and iridium. Of these, platinum, rhodium and iridium are preferably used. These may be used alone or in combination of two or more. Preferred combinations include platinum-rhodium, rhodium-iridium, platinum-iridium and platinum-rhodium-iridium combinations. Of these, a combination of platinum and rhodium is preferably used. There is no restriction | limiting in particular about the ratio of each element in these combinations, and an optimal ratio can be determined suitably.

In the component (B), zirconium and cerium are converted into zirconium oxide (ZrO ₂ ) and cerium oxide (CeO ₂ ), respectively, and are 100: 2 to 100: 100 (mass ratio), preferably 100: 10 to 100 : 60 (mass ratio), more preferably 100: 20 to 100: 40 (mass ratio) (that is, zirconium oxide (ZrO ₂ ): cerium oxide (CeO ₂ ) (mass ratio)) = 100: 2 to 100: 100, The zirconium-cerium composite oxide is preferably contained at a ratio of 100: 10 to 100: 60, more preferably 100: 20 to 100: 40).

Regarding the component (B), it can be basically confirmed that zirconium and cerium form a composite oxide because no peak of cerium oxide is detected in X-ray diffraction analysis. However, depending on the preparation conditions, when zirconium oxide (ZrO ₂ ): cerium oxide (CeO ₂ ) (mass ratio) exceeds 100: 50, a broad peak of cerium oxide with low crystallinity is observed by X-ray diffraction. There is. Therefore, in the present invention, such an oxide (intimate mixture) in which cerium oxide is partly intimately mixed is referred to as “zirconium-cerium composite oxide”. However, the zirconium-cerium composite oxide used in the present invention is preferably one in which the crystal peak of cerium oxide does not appear in X-ray diffraction analysis. In this respect, zirconium oxide (ZrO ₂ ) and cerium oxide (CeO ₂ ) Is preferably 100: 20 to 100: 40.

In the zirconium-cerium composite oxide, by adjusting the ratio (mass ratio) of zirconium oxide (ZrO ₂ ) to cerium oxide (CeO ₂ ) in the range of 100: 2 to 100: 100, high activity and durability are achieved. It is possible to obtain a catalyst for partial oxidation excellent in the above.

  Cerium oxide has an oxygen storage capacity, and has the effect of changing the electronic state of the platinum group element, which is the active component, by releasing or taking in oxygen, so if the content of cerium oxide is too small, its addition On the other hand, if the effect becomes insufficient, and if the content of cerium oxide is too large, the surface area of cerium oxide decreases when used for a long time at a high temperature, and the effect is considered to be reduced.

  The zirconium-cerium composite oxide is at least one element selected from rare earth elements other than cerium and alkaline earth elements (hereinafter also referred to as “component (D)” and “component (E)”, respectively). It is preferable in terms of improving the durability of the partial oxidation catalyst. Especially, what contains a component (D) is used suitably.

  Examples of rare earth elements other than cerium of component (D) include Sc, Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb. Moreover, Mg, Ca, Sr, and Ba are mentioned as an alkaline-earth element of a component (E). These may be used alone or in combination of two or more.

The use amount of the component (D) and / or component (E), if as the oxide (component _{(D), D 2 O 3} (D: rare earth element other than cerium) terms, also components (E) In this case, it is 0.1 to 15% by mass, preferably 0.1 to 10% by mass, based on the total mass of EO (E: converted to alkaline earth element) and component (B). Incidentally, in component (B), preferably less than component (D) and / or the content of component _{(E) (D 2 O 3} , EO conversion) the content of cerium oxide (CeO ₂ conversion) . When the content of the component (D) and / or the component (E) is larger than the content of cerium oxide (CeO ₂ ), these may sometimes inhibit the combined effect of zirconium and cerium.

The zirconium-cerium composite oxide of component (B) can be easily prepared, for example, according to the following method.
(1) After mixing a cerium salt aqueous solution and a zirconium salt aqueous solution, drying and baking.
(2) A cerium salt aqueous solution and a zirconium salt aqueous solution are mixed and coprecipitated using an ammonium compound or the like, and then dried and fired.
(3) After mixing cerium oxide and zirconium oxide, a solid phase reaction is performed.
(4) After immersing the zirconium salt aqueous solution in cerium oxide, drying and firing, or immersing the cerium salt aqueous solution in zirconium oxide and then drying and firing.
(5) After impregnating a refractory inorganic oxide such as activated alumina with a cerium salt aqueous solution and a zirconium salt aqueous solution, drying and firing.

  The cerium raw material and the zirconium raw material are not particularly limited, and various compounds can be used. As the cerium raw material, commercially available cerium oxide, cerium oxide sol, cerium nitrate, cerium chloride, cerium carbonate, cerium acetate, cerium salt compounds such as cerium acetate, and cerium oxide and cerium hydroxide prepared from these compounds can be used. Zirconium raw materials include commercially available zirconium oxide, zirconium oxide sol, various halides such as zirconium tetrachloride or partial hydrolysis products thereof, various oxyhalides such as zirconyl chloride (zirconium oxychloride), zirconyl sulfate, nitric acid Various oxygenates such as zirconium and zirconyl nitrate, carbonates such as zirconium carbonate and zirconyl carbonate, various organic acid salts such as zirconium acetate, zirconyl acetate and zirconyl oxalate, alkoxides of zirconium, various complex salts and the like can be used. .

  The calcination in the methods (1) to (5) may be carried out, for example, in air at 300 to 800 ° C., preferably 400 to 800 ° C. for about 0.5 to 3 hours, thereby obtaining a zirconium-cerium composite oxide. It is done.

  In addition, when the rare earth element of component (D) and / or the alkaline earth element of component (E) is contained, starting of component (D) and / or component (E) in the above methods (1) to (5) What is necessary is just to add a raw material.

Examples of the refractory inorganic oxide of component (C) include activated alumina, zirconia, silica, titania, spinel, mullite, alumina-silica, alumina-zirconia, and titania-silica. These can be used alone or in combination of two or more. Among these, activated alumina is particularly preferably used because it has a large specific surface area and a large contact area with the reaction gas, and thus can improve partial oxidation efficiency and is excellent in high-temperature heat resistance. Further, as will be described later, activated alumina can retain the characteristics of a white metal element over a long period of time when it carries a platinum group element. Examples of the activated alumina include α-alumina, γ-alumina, δ-alumina, θ-alumina, and η-alumina. Among these, activated alumina having a specific surface area of 25 to 250 m ² / g is preferably used.

  As the activated alumina, usually commercially available alumina powder is used. In addition, boehmite, hydrated alumina in a pseudo boehmite state, aluminum hydroxide, or the like, which becomes active alumina by being fired after being supported on a monolith carrier, may be used. Alternatively, activated alumina obtained by adding an alkali to an aqueous aluminum salt solution such as aluminum nitrate to form a hydroxide precipitate, and drying and firing the precipitate may be used. Alternatively, activated alumina obtained by a sol-gel method in which an alkoxide such as aluminum isopropoxide is hydrolyzed to prepare an alumina gel, which is dried and fired may be used.

  As zirconia, commercially available zirconia powder can be used. In addition, various halides such as zirconia sol and zirconium tetrachloride or partial hydrolysis products thereof, various oxyhalides such as zirconyl chloride (zirconium oxychloride), various oxygen acids such as zirconyl sulfate, zirconium nitrate and zirconyl nitrate Zirconia obtained by drying and baking salt, carbonate such as zirconium carbonate and zirconyl carbonate, various organic acid salts such as zirconium acetate, zirconyl acetate and zirconyl oxalate, zirconium alkoxide, various complex salts and the like.

In the partial oxidation catalyst of the present invention, the component (A) is supported on a part or all of the component (C). In this case, the component (C) is preferably activated alumina.

  The amount of the catalyst component containing component (A), component (B) and component (C) supported on the monolith support should be appropriately selected within the range where a highly active and highly durable catalyst for partial oxidation can be obtained. Usually, it is 35 to 400 g, preferably 70 to 300 g, per liter of monolithic carrier. If the supported amount is too small, sufficient catalytic activity cannot be obtained, and if it is too large, clogging or increased pressure loss may be caused.

  About the usage-amount of a component (A), it is 0.3-5g normally per monolith carrier 1L, Preferably it is 0.5-3g. If the amount used is too small, sufficient catalytic activity cannot be obtained, and even if it is used in a large amount, an effect commensurate with it cannot be obtained, and problems such as an increase in cost occur.

In addition, after carrying | supporting a component (A) on a part or all of a component (C) according to the method of a postscript, a slurry is prepared and the catalyst for partial oxidation of this invention is manufactured by carrying | supporting this on a monolith support | carrier. In this case, the amount of the component (A) supported is 0.4 to 40% by mass, preferably 1 to 30% by mass, more preferably 5 to 25% by mass. The “support amount of platinum group element (or the support amount of component (A))” in the present invention is defined by the following formula.
Amount of white metal element supported (mass%) = [(mass of component (A)) / (mass of component (A) + mass of component (C) supporting component (A))] (× 100)
By using the component (A) in the above range, the heat resistance of the catalyst for partial oxidation can be improved and the catalytic activity can be prevented from being lowered. However, if the amount is too large, the component (A) that contributes to the reaction is effective. Since the active sites are reduced, the reaction efficiency during the partial oxidation reaction may be reduced.

  Conventionally, it was generally considered that a platinum group element such as component (A) was supported on other catalyst components as uniformly as possible (highly dispersed support) to obtain a catalyst with good catalytic performance. However, in the partial oxidation catalyst of the present invention, the component (A) is supported on a part or all of the component (C) in the concentration range as described above (high concentration support), thereby improving the durability. Thus, the present invention has been completed based on such novel findings.

  As described above, among the partial oxidation catalysts of the present invention, the amount of component (A) used is 0.3 to 5 g per liter of monolith support, and component (A) is a part of component (C) or The partial oxidation catalyst supported so that the supported amount is 0.4 to 40% by mass is preferably used for all.

  In addition, there is no restriction | limiting in particular about the ratio with respect to all the components (C) of the component (C) which carry | supports a component (A), It uses suitably so that the usage-amount and loading amount of a component (A) may be in the above ranges. Can be determined.

  In the partial oxidation catalyst of the present invention, the component (C) supporting the component (A) is preferably uniformly dispersed in the partial oxidation catalyst.

Component for the amount of (B), the mass ratio of cerium in the platinum group elements and of component (A) (B) (PGE: cerium oxide (CeO ₂₎ equivalent) 1: 1 to 1: 200, preferably 1: 3 to 1: 100, more preferably 1: 5 to 1:50. If the ratio of cerium to the platinum group element is too small, sufficient durability cannot be obtained. On the other hand, if the ratio is too large, the platinum group element and cerium may cause an undesirable interaction to reduce durability.

The use amount of the component (C), the mass ratio of cerium oxide contained in the component (B) (CeO ₂ conversion) and component (C) is 1: 0.5 to 1: 150, preferably 1: 1 to The ratio should be 1:80, more preferably 1: 1 to 1:40. If the ratio of the component (C) to the cerium in the component (B) is too large, sufficient durability cannot be obtained. On the other hand, if the ratio is too small, the platinum group element and cerium cause an unfavorable interaction and decrease the durability. Sometimes.

  In addition to the above components (A), (B) and (C), the catalyst component of the present invention includes metal elements belonging to periodic table groups I, II, IIIB, IV, V, VIB, VIIB and VIII, for example, , Na, K, Cs, Ni, Co, Fe, Cr, Cu, V, Pr, Mg, Mo, W, Mn, Zn, Ga, Y, Ti, Ba, Re, Bi, Nb, Ta, La, Ag And one or more of Au may be contained. When these metal elements are present in the catalyst component as solid solutions with metals, metal oxides, or platinum group elements, the catalytic action of component (A) is promoted and contributes to its stabilization, and further hydrogen Effects such as increasing the selectivity can be obtained.

The preparation of the catalyst for partial oxidation of the present invention will be described below by taking a typical method as an example.
<Method>
After supporting the platinum group element on a part or all of the refractory inorganic oxide, the remaining refractory inorganic oxide not supporting the platinum group element (A) is added to the refractory inorganic oxide supporting the platinum group element. Supply the oxide and zirconium-cerium composite oxide together with the zirconium-cerium composite oxide to a pulverizer such as a ball mill, prepare a slurry by wet pulverization, contact the monolith support with this slurry, and then dry. Bake.

As the platinum group element source, various compounds of platinum group elements can be used. For example, platinum compounds include PtCl ₄ , H ₂ PtCl ₆ , Pt (NH ₃ ) ₄ Cl ₂ , (NH ₄ ) ₂ PtCl ₂ , H ₂ PtBr ₆ , NH ₄ [Pt (C ₂ H ₄ ) Cl ₃ ]. , Pt (NH ₃ ) ₄ (OH) ₂ , Pt (NH ₃ ) ₂ (NO ₂ ) _{2 and the} like. Examples of rhodium compounds include (NH ₄ ) ₂ RhCl ₆ , Rh (NH ₃ ) ₅ Cl ₃ , RhCl ₃ , Rh (NO ₃ ) _{3 and the} like. Examples of the palladium compound include (NH ₄ ) ₂ PdCl ₄ , Pd (NH ₃ ) ₄ Cl ₂ , PdCl ₂ , Pd (NO ₃ ) _{2 and the} like. Examples of the ruthenium compound include RuCl ₃ , Ru (NO ₃ ) ₃ , Ru ₂ (OH) ₂ Cl ₄ .7NH _{3 and the} like. Examples of the iridium compound include (NH ₄ ) ₂ IrCl ₆ , IrCl ₃ , H ₂ IrCl _{6 and the} like.

  When preparing the slurry, in order to adjust the viscosity of the slurry and improve stability, acids such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid and oxalic acid, basic compounds such as ammonia and tetraammonium hydroxide, polyacrylic acid and polyvinyl A polymer compound such as alcohol may be added as necessary.

  As the method for contacting the monolithic carrier and the slurry, the catalyst component can be uniformly supported when the monolithic carrier is immersed in the slurry, and this immersion method is preferably used. After immersion, it is preferable to dry after removing excess slurry (for example, slurry remaining in the cell) adhering to the monolith carrier by a method such as air blowing.

  There is no particular limitation on the drying method, and any method can be used as long as it can remove water from the slurry. Drying may be performed at normal temperature or high temperature. When fired after drying, the catalyst component can be firmly fixed to the monolith support. About baking conditions, what is necessary is just to bake at 400-800 degreeC in air or a reducing atmosphere, for example. When a required amount of catalyst component cannot be supported by a single operation, the above immersion-drying-firing operation may be repeated.

  Specifically, the case where activated alumina is used as the refractory inorganic oxide will be described as an example. A solution in which a platinum group element source is dissolved, usually active in an aqueous solution so as to achieve a desired amount of platinum group element supported. After contacting alumina, it is dried and fired.

For the purpose of improving the solubility of the platinum group element source and adjusting the pH, an inorganic acid such as hydrochloric acid, sulfuric acid or nitric acid, or an organic acid such as acetic acid or oxalic acid may be added to the aqueous solution.
In order to bring the platinum group element source aqueous solution into contact with the activated alumina, a method such as an impregnation method, a dipping method, a wet adsorption method, a spray method, or a coating method can be appropriately selected. Of these, the impregnation method is preferably used. An optimum condition can be selected as appropriate for the contact condition. For example, it may be contacted at a temperature of about room temperature to 90 ° C., preferably under atmospheric pressure or under reduced pressure, and if necessary, heated.

  In the partial oxidation catalyst of the present invention, as described above, it is preferable to support two or more types of platinum group elements. In such a case, an aqueous solution containing two or more types of platinum group element sources is prepared. Even if activated alumina is brought into contact with this aqueous solution and two or more kinds of platinum group elements are simultaneously supported on activated alumina, or an aqueous solution containing two or more kinds of platinum group element sources individually is prepared and activated in these aqueous solutions. Alumina may be contacted sequentially.

  After bringing the platinum group element source aqueous solution and activated alumina into contact with each other and drying, the platinum group is baked in air or in a reducing atmosphere at a temperature in the range of 300 to 600 ° C. for about 2 to 6 hours, for example. An activated alumina carrying elements is obtained.

  Subsequent slurry preparation, contact with the monolith support, firing, and the like can be performed in accordance with the method described in the above method.

  In addition, the refractory inorganic oxide carrying the platinum group element or the zirconium-cerium composite oxide may be agglomerated depending on the production conditions to increase the particle diameter. For example, in the wet pulverization step during slurry adjustment, By adjusting the pulverization time and the like, the range can be set to, for example, 0.5 to 20 μm.

  In addition to the components (A) to (C), when the component (F) is used, for example, a salt compound or oxide of each metal element is mixed into the slurry, or a zirconium-cerium composite oxide or What is necessary is just to fix and use beforehand to a refractory inorganic oxide. For this immobilization, the same method as in the case where a platinum group element is supported on the refractory inorganic oxide can be employed. In addition, any generally known method may be employed as appropriate, for example, after the components (A) to (C) are supported and fired on the monolith support and the component (F) is supported by a dipping method or the like.

As described above, the component (A) is preferably supported in advance on the component (B) and / or the component (C), particularly the component (C). Component (B) or component (C) carrying the component (A), the average particle diameter in the finished catalyst after the catalyst component is carried on the monolith support (determined by the following measurement method, The “EPMA method average particle size”) is 0.5 to 20 μm, preferably 1 to 10 μm.
<Measurement method>
Using an Electron Probe Micro Analyzer (EPMA), 30 X-ray images of platinum group elements were randomly taken at a magnification of 3000 using the Electron Probe Micro Analyzer (EPMA). The diameters of the particles in these photographs are measured, and the average particle diameter is determined based on the measured values.

  Thus, by dispersing the component (B) or the component (C) carrying the component (A) as agglomerated particles having a relatively large average particle diameter in the catalyst component, a catalyst such as activity as a catalyst for partial oxidation A long-life partial oxidation catalyst that exhibits excellent durability even at high temperatures while maintaining performance can be obtained.

  In order to disperse the component (B) or the component (C) carrying the component (A) in the catalyst component as aggregated particles having a relatively large average particle diameter as described above, a powdery or pellety component After impregnating and supporting the component (A) in (C), it may be placed in a ball mill or the like and wet pulverized to adjust to the target average particle size.

  Next, a method for producing a hydrogen-containing gas by partially oxidizing hydrocarbons using the above-described partial oxidation catalyst will be described.

  According to the present invention, hydrocarbons, in particular hydrocarbon-containing gases, more specifically, by bringing a raw material gas containing hydrocarbons and oxygen into contact with the above-mentioned partial oxidation catalyst, the hydrocarbons are partially oxidized and hydrogenated. A hydrogen-containing gas mainly containing hydrogen and carbon monoxide is produced.

  As the hydrocarbon, light hydrocarbons such as methane, propane, butane, heptane and hexane, and petroleum hydrocarbons such as gasoline, kerosene and naphtha can be used. For example, natural gas or liquefied natural gas based on methane, city gas based on this liquefied natural gas, and LPG (liquefied petroleum gas) based on propane and butane are also abundant in resources. It is suitable because it is easily available. Further, various liquid fuels such as methanol or dimethyl ether starting from natural gas, and biogas mainly composed of methane are also preferable from the viewpoint of effective use of resources. The “hydrocarbon” of the present invention includes not only hydrocarbons such as methane and propane, but also organic compounds that generate a hydrogen-containing gas by partial oxidation such as methanol and dimethyl ether.

In the method of the present invention, even if the raw material gas contains a sulfur component that becomes a catalyst poison, the partial oxidation reaction can be performed without removing it. For example, natural gas contains sulfur as impurities (for example, about 5 to ³⁰ mg / Nm ³ as total sulfur) in addition to hydrocarbons such as methane, ethane, and propane. In the case of using a gas, conventionally, it has been necessary to perform a partial oxidation reaction after removing sulfur by desulfurization treatment. However, since the catalyst for partial oxidation of the present invention has excellent durability against a catalyst poison such as a sulfur content, even if a raw material gas containing a sulfur content is used as it is, Deterioration is suppressed and the partial oxidation reaction can be carried out stably over a long period of time.

  The raw material gas of the present invention is usually obtained by mixing a hydrocarbon-containing gas and an oxygen-containing gas. Usually, air is used as the oxygen-containing gas. Regarding the ratio between the hydrocarbon-containing gas and the oxygen-oxygen-containing gas, the number of moles of oxygen molecules per one carbon atom (oxygen molecule / carbon atom ratio) is 0.45 to 0.65, preferably 0.48 to 0. .6 is preferable for efficient partial oxidation of hydrocarbons.

  The partial oxidation reaction of the present invention can be carried out according to a method generally known for producing a hydrogen-containing gas by partial oxidation of hydrocarbons, except that the catalyst for partial oxidation of the present invention is used as a catalyst. As the reaction system, a continuous flow system in which the raw material gas is continuously brought into contact with the catalyst is preferably used.

The pressure during the partial oxidation reaction is normal pressure or more and 5 MPa · G or less, preferably 3 MPa · G or less. Gas space velocity (SV) is 3,000~500,000H ^-1, and it is preferably a 10,000~300,000H ^-1. Regarding the temperature, in order to perform an efficient partial oxidation reaction while preventing thermal deterioration of the catalyst for partial oxidation, the catalyst layer temperature is in the range of 600 to 1,000 ° C., preferably 700 to 950 ° C. It is good to do.

  In order to perform the partial oxidation reaction while maintaining the catalyst layer temperature within the above range, for example, a method in which the raw material gas is preheated and then introduced into the catalyst layer or a method in which the catalyst layer is heated can be employed.

  In the case of the method of preheating the raw material gas, the preheating temperature varies depending on the type of hydrocarbon, the composition of the raw material gas, the reaction conditions, etc., but generally it is preferable to heat to 200 to 700 ° C., preferably 300 to 600 ° C. . After the reaction in the catalyst layer starts, the temperature of the catalyst layer rises due to the reaction heat, and the reaction becomes self-supporting, so that the source gas need not be preheated. Of course, the raw material gas may be preheated as necessary in consideration of the heat balance of the entire reaction system.

  In the case of the method of heating the catalyst layer, the catalyst layer is heated to 200 to 700 ° C., preferably 300 to 600 ° C., prior to the introduction of the raw material gas, and heating of the catalyst layer is stopped after the reaction starts. Good. For heating the catalyst layer, a method of introducing heated air or nitrogen into the catalyst layer, a method of heating the catalyst layer from the outside with a heater, methanol, hydrogen, dimethyl ether, or the like hydrocarbons used in the present invention is easier. A method of introducing a gas containing an oxidizable compound into the catalyst layer and heating the catalyst layer with the reaction heat can be appropriately selected.

  In the partial oxidation reaction of hydrocarbons, steam is usually added to the raw material gas in order to prevent carbon deposition. However, the partial oxidation catalyst of the present invention has zero carbon deposition even in the absence of water vapor, or a very small amount that does not affect the catalytic activity even if it is deposited. It can be carried out efficiently even in the absence of water vapor.

  In the case of the partial oxidation catalyst of the present invention, when the partial oxidation reaction of hydrocarbon is performed by contacting with a raw material gas containing hydrocarbon, oxygen and water vapor, the hydrogen production ratio increases. Moreover, since exothermic reaction (partial oxidation of hydrocarbon) and endothermic reaction (reaction between hydrocarbon and water vapor) occur, the amount of heat generated can be suppressed as compared with the case where water vapor is not added. The oxygen-containing gas or water vapor may be introduced into the catalyst layer after being mixed with the hydrocarbon-containing gas, or may be introduced separately into the catalyst layer.

  The hydrogen-containing gas containing hydrogen and carbon monoxide obtained by the method of the present invention can be used for various applications similar to the hydrogen-containing gas obtained by the prior art.

  Specifically, for example, it can be suitably used as a fuel for a fuel cell. Among fuel cells, molten carbonate fuel cells and solid oxide fuel cells, which are classified as high-temperature operating types, can use carbon monoxide and hydrocarbons as fuel in addition to hydrogen. Is preferably a hydrogen-containing gas obtained by the method of the present invention. In principle, a high-temperature-operated fuel cell is said to be able to perform a partial oxidation reaction of hydrocarbons in the cell (internal reforming) by the catalytic action of an electrode. However, in practice, problems such as carbon deposition occur depending on the type of hydrocarbon and impurities contained in the hydrocarbon, and therefore the total amount of hydrocarbon may not be internally reformed. For this reason, it is necessary to pretreat the hydrocarbon before introducing the hydrocarbon into the fuel cell, but the partial oxidation catalyst of the present invention is also suitably used for such a hydrocarbon pretreatment.

  In addition, the hydrogen-containing gas obtained by the method of the present invention further reduces the carbon monoxide concentration by CO modification reaction, or removes impurities by a cryogenic separation method, PAS method, hydrogen storage alloy or palladium membrane diffusion method, etc. Thus, high purity hydrogen can be obtained. In order to reduce the carbon monoxide contained in the hydrogen gas, for example, a hydrogen-containing gas is introduced into a carbon monoxide modifier in the presence or absence of water vapor, where a CO modification reaction is performed. Carbon monoxide may be oxidized and converted to carbon dioxide gas. For this CO modification reaction, for example, a known catalyst mainly composed of copper or iron can be used. By the CO modification reaction, the carbon monoxide concentration can be reduced to about 1%, but even at this level of carbon monoxide, the electrode is poisoned in the low temperature operation type solid polymer fuel cell, and the performance is lowered. For this reason, in order to prevent such catalyst poisoning, for example, a small amount of oxygen is added to the gas after the CO modification reaction, and carbon monoxide is selectively removed, so that the carbon monoxide concentration is 100 ppm. The following is recommended.

The invention will now be described in more detail by way of examples illustrating advantageous embodiments of the invention. “%” Is “% by mass” unless otherwise specified.
Reference example 1
(Carrier)
A cordierite honeycomb carrier (manufactured by Nippon Choshi Co., Ltd.) having 400 cells per square centimeter in cross-sectional area was cut into an outer diameter of 25.4 mm and a length of 77 mm (carrier volume of 39.0 ml). A carrier was used.
(Platinum group element-supported activated alumina)
A nitric acid aqueous solution of dinitrodiamine platinum containing 22.727 g of platinum and a rhodium nitrate aqueous solution containing 4.545 g of rhodium were mixed. The solution was impregnated with 200 g of activated alumina having a specific surface area of 160 m ² / g, and then dried at 150 ° C. overnight (15 hours) to remove moisture. After drying, the powder was calcined in air at 400 ° C. for 2 hours to obtain activated alumina carrying platinum group element 12% (platinum 10%, rhodium 2%).
(Zirconium-cerium composite oxide)
An aqueous cerium nitrate solution was added to commercially available zirconium oxide (specific surface area 100 m ² / g) so that zirconium oxide (ZrO ₂ ): cerium oxide (CeO ₂ ) (mass ratio) was 100: 35, and mixed uniformly. . The obtained mixed slurry was dried at 120 ° C. to remove moisture, and then fired in air at 500 ° C. for 1 hour to obtain zirconium-cerium oxide. As a result of X-ray diffraction analysis, no crystal peak of cerium oxide was detected, and this oxide was confirmed to be a zirconium-cerium composite oxide.

The platinum group element-supported activated alumina 7.20 g and the zirconium-cerium composite oxide 69.6 g obtained above, 69.6 g of activated alumina (specific surface area 105 m ² / g), 133 g of pure water and 4.2 g of acetic acid. And wet-ground with a ball mill to obtain an aqueous slurry.

  The aqueous slurry was impregnated with the carrier to adhere the slurry, and then taken out. Next, the carrier is blown with compressed air to remove the slurry remaining in the cell, dried at 150 ° C. to adhere the catalyst component, and then calcined in air at 500 ° C. for 1 hour to remove the catalyst component. The carrier was firmly supported. The carrier carrying the catalyst component was further immersed in the slurry and the same operation was repeated to carry 9.8 g of the catalyst component on the carrier to obtain a finished catalyst (a).

The properties of the catalyst (a) were as follows.
Zirconium oxide (ZrO ₂ ): cerium oxide (CeO ₂ ) (mass ratio) = 100: 35
Amount of catalyst component used per liter of monolith support: 251 g
Amount of platinum group element used per liter of monolith support: 1.45 g (1.21 g of platinum, 0.24 g of rhodium)
Mass ratio of platinum group element: cerium oxide (CeO ₂ ) in the catalyst = 1: 22
Cerium oxide (CeO ₂ ) in catalyst: active alumina mass ratio = 1: 4
Amount of platinum group element supported on activated alumina: 12%
EPMA measurement average particle diameter of platinum group element-supported activated alumina: 4 μm
According to the distribution photograph of the platinum group element-supported activated alumina, the activated alumina particles were uniformly dispersed.
Example 1
(Zirconium-cerium-yttrium composite oxide)
Add cerium nitrate aqueous solution and yttrium nitrate to commercially available zirconium oxide (specific surface area 100 m ² / g) so that zirconium oxide: cerium oxide: yttrium oxide (Y ₂ O ₃ ) (mass ratio) is 100: 35: 2. And mixed uniformly. The obtained mixed slurry was dried at 120 ° C. to remove moisture, and then fired in air at 500 ° C. for 1 hour to obtain zirconium-cerium-yttrium oxide. As a result of X-ray diffraction analysis, only the crystal peak of zirconium oxide was detected, and this oxide was confirmed to be a zirconium-cerium-yttrium composite oxide.

Hereinafter, 7.20 g of the same platinum group element-supported activated alumina prepared in Reference Example 1, 73.2 g of the above zirconium-cerium-yttrium composite oxide, and 69.6 g of activated alumina (specific surface area 105 m ^{2 /} g) were used. Except for the above, a slurry was prepared in the same manner as in Reference Example 1, and then the finished catalyst (b) was obtained so that the amount of the catalyst component supported on the carrier was 9.7 g.

The properties of the catalyst (b) were as follows.
Zirconium oxide: cerium oxide: yttrium oxide (Y ₂ O ₃ ) (mass ratio) = 100: 35: 2
Amount of catalyst component used per liter of monolith support: 248 g
Amount of platinum group element used per liter of monolith support: 1.43 g (platinum 1.19 g, rhodium 0.24 g)
Mass ratio of platinum group element: cerium oxide (CeO ₂ ) in the catalyst = 1: 22
Cerium oxide (CeO ₂ ) in catalyst: mass ratio of activated alumina = 1: 4.1
Amount of platinum group element supported on activated alumina: 12%
EPMA measurement average particle diameter of platinum group element-supported activated alumina: 4 μm
According to the distribution photograph of the platinum group element-supported activated alumina, the activated alumina particles were uniformly dispersed.

Example 2
7.20 g of platinum group element-supported activated alumina prepared in Reference Example 1 was weighed, placed in a ball mill together with 70 g of pure water and 4.2 g of acetic acid, and wet pulverized for 12 hours. To this aqueous slurry, 73.2 g of the zirconium-cerium-yttrium composite oxide prepared in Example 1 , 69.6 g of activated alumina (specific surface area 105 m ² / g) and 63 g of pure water were added, and wet grinding was continued for 20 hours. An aqueous slurry was prepared.

Thereafter, using the above aqueous slurry, a catalyst (c) was prepared in the same manner as in Reference Example 1 so that the amount of the catalyst component supported on the monolith support was 9.8 g.

The properties of the catalyst (c) were as follows.
Zirconium oxide: cerium oxide: yttrium oxide (Y ₂ O ₃ ) (mass ratio) = 100: 35: 2
Amount of catalyst component used per liter of monolith support: 250 g
Amount of platinum group element used per liter of monolithic carrier: 1.44 g (platinum 1.20 g, rhodium 0.24 g)
Mass ratio of platinum group element: cerium oxide (CeO ₂ ) in the catalyst = 1: 22
Cerium oxide (CeO ₂ ) in catalyst: mass ratio of activated alumina = 1: 4.1
Amount of platinum group element supported on activated alumina: 12%
When the coating layer of the catalyst (c) was analyzed by EPMA in the same manner as in Reference Example 1, platinum group element-supporting activated alumina particles of 0.5 μm or more were not detected.

Comparative Example 1
Nitrogen of dinitrodiamine platinum containing 73.2 g of the zirconium-cerium-yttrium composite oxide prepared in Example 1 and 75.6 g of activated alumina (specific surface area 105 m ^{2 /} g) in a ball mill and containing 0.80 g of platinum in this ball mill. An aqueous solution and a rhodium nitrate aqueous solution containing 0.40 g as rhodium were added, and 118 g of pure water and 3.5 g of acetic acid were further added, followed by wet grinding for 20 hours to prepare an aqueous slurry.
Thereafter, using the above aqueous slurry, a catalyst ( d ) was obtained in the same manner as in Reference Example 1 so that the amount of catalyst component supported on the monolith support was 10.0 g.
The properties of the catalyst ( d ) were as follows.
Zirconium oxide (ZrO ₂ ): Cerium oxide (CeO ₂ ): Yttrium oxide (Y ₂ O ₃ ) (mass ratio) = 100: 35: 2
Amount of catalyst component used per liter of monolith support: 256 g
Amount of platinum group element used per liter of monolith support: 2.05 g (platinum 1.37 g, rhodium 0.68 g)
Mass ratio of platinum group element: cerium oxide (CeO ₂ ) in the catalyst = 1: 16
Cerium oxide (CeO ₂ ) in catalyst: active alumina mass ratio = 1: 4
Amount of platinum group element supported (platinum group element + active alumina + zirconium-cerium-yttrium composite oxide based on total amount): 0.8%
Comparative Example 2
(Zirconium-cerium composite oxide)
A zirconium-cerium composite oxide was prepared in the same manner as in Reference Example 1 except that zirconium oxide: cerium oxide was 100: 1.

Hereinafter, except that 7.20 g of the same platinum group element-supported activated alumina used in Reference Example 1, 73.2 g of the above zirconium-cerium composite oxide and 69.6 g of activated alumina (specific surface area 105 m ^{2 /} g) were used. A slurry was prepared in the same manner as in Reference Example 1, and then a comparative catalyst ( e ) was obtained so that the amount of the catalyst component supported on the support was 9.9 g.

The properties of this catalyst ( e ) were as follows.
Zirconium oxide: cerium oxide (mass ratio) = 100: 1
Amount of catalyst component used per liter of monolith support: 255 g
Amount of platinum group element used per liter of monolith support: 1.47 g (1.22 g of platinum, 0.25 g of rhodium)
Mass ratio of platinum group element: cerium oxide (CeO ₂ ) in the catalyst = 1: 0.8
Cerium oxide (CeO ₂ ) in catalyst: active alumina mass ratio = 1: 105
Amount of platinum group element supported on activated alumina: 12%
EPMA measurement average particle diameter of platinum group element-supported activated alumina: 4 μm
According to the distribution photograph of the platinum group element-supported activated alumina, the activated alumina particles were uniformly dispersed.
Comparative Example 3
(Zirconium-cerium-yttrium composite oxide)
Zirconium-cerium-yttrium oxide was obtained in the same manner as in Example 1 except that zirconium oxide: cerium oxide: yttrium oxide (Y ₂ O ₃ ) (mass ratio) was 100: 150: 5.

Hereinafter, 7.20 g of the same platinum group element-supported activated alumina as used in Reference Example 1, 73.2 g of the above zirconium-cerium-yttrium composite oxide and 69.6 g of activated alumina (specific surface area 105 m ^{2 /} g) were used. Except for the above, a slurry was prepared in the same manner as in Reference Example 1, and then a catalyst for comparison ( f ) was obtained so that the amount of the catalyst component supported on the carrier was 9.9 g.

The properties of the catalyst ( f ) were as follows.
Zirconium oxide: cerium oxide: yttrium oxide (Y ₂ O ₃ ) (mass ratio) = 100: 150: 5
Amount of catalyst component used per liter of monolith support: 253 g
Amount of platinum group element used per liter of monolith support: 1.46 g (platinum 1.22 g, rhodium 0.24 g)
Mass ratio of platinum group element: cerium oxide (CeO ₂ ) in the catalyst = 1: 50
Cerium oxide (CeO ₂ ) in catalyst: mass ratio of activated alumina = 1: 1.8
Amount of platinum group element supported on activated alumina: 12%
EPMA measurement average particle diameter of platinum group element-supported activated alumina: 4 μm
According to the distribution photograph of the platinum group element-supported activated alumina, the activated alumina particles were uniformly dispersed.
Comparative Example 4
(Zirconium-cerium-yttrium composite oxide)
Zirconium-cerium-yttrium oxide was obtained in the same manner as in Example 1 except that zirconium oxide: cerium oxide: yttrium oxide (Y ₂ O ₃ ) (mass ratio) was 100: 1: 0.5. .

120.0 g of the zirconium-cerium-yttrium composite oxide and 28.8 g of activated alumina (specific surface area 105 m ² / g) were placed in a ball mill, and dinitrodiamine platinum aqueous nitric acid solution containing 0.80 g as platinum and 0 as rhodium. An aqueous rhodium nitrate solution containing .40 g was added, and 118 g of pure water and 3.5 g of acetic acid were further added, followed by wet grinding for 20 hours to prepare an aqueous slurry. Hereinafter, using this aqueous slurry, a catalyst for comparison ( g ) was prepared in the same manner as in Example 1 so that the amount of the catalyst component supported on the carrier was 9.8 g .
The properties of this catalyst ( g ) were as follows.
Zirconium oxide: cerium oxide: yttrium oxide (Y ₂ O ₃ ) (mass ratio) = 100: 1: 0.5
Amount of catalyst component used per liter of monolith support: 252 g
Amount of platinum group element used per liter of monolith support: 2.02 g (1.35 g of platinum, 0.67 g of rhodium)
Mass ratio of platinum group element: cerium oxide (CeO ₂ ) in the catalyst = 1: 1
Cerium oxide (CeO ₂ ) in catalyst: active alumina mass ratio = 1: 24
Amount of platinum group element supported (platinum group element + active alumina + zirconium-cerium-yttrium composite oxide based on total amount): 0.8%
EPMA measurement average particle diameter of platinum group element-supported activated alumina: 4 μm
According to the distribution photograph of the platinum group element-supported activated alumina, the activated alumina particles were uniformly dispersed.
Comparative Example 5
In Reference Example 1, a comparative catalyst ( h ) was used in the same manner as in Reference Example 1 except that a mixture of zirconium oxide and cerium oxide (ZrO ₂ : CeO ₂ = 100: 35) was used instead of the zirconium-cerium composite oxide. Manufactured.
Comparative Example 6
In Comparative Example 1, a comparative catalyst ( i ) was produced in the same manner as in Reference Example 1, except that no zirconium-cerium composite oxide was used.
Example 3
The catalysts (a) to ( i ) were subjected to the following accelerated durability test and evaluated for durability.

Each catalyst was cut into a size of 7 × 7 × 10 mm and filled into an Inconel reaction tube kept warm with a refractory. A source gas obtained by mixing city gas 13A (88 volume% methane, sulfur content 5 ppm) as the carbon hydrogen gas and air as the oxygen-containing gas so that the oxygen / carbon ratio is 0.5 / 1 is 200. After preheating to ° C., the catalyst layer was supplied at a space velocity (STP) of 400,000 h ⁻¹ to carry out a partial oxidation reaction.

The partial oxidation reaction gas was analyzed using gas chromatography (Gas Chromatography GC-8A manufactured by Shimadzu Corporation), and the methane conversion rate after the initial reaction and 150 hours later was obtained. Similarly, hydrogen selectivity was determined.
Methane conversion rate (%) = (CO + CO ₂ ) / (CO + CO ₂ + CH ₄ )) (× 100)
(Here, CO, CO ₂ and CH ₄ represent the concentrations of carbon monoxide, carbon dioxide and methane, respectively, at the outlet of the reaction tube.)
Hydrogen selectivity (%) = (1 / 2H ₂ ) / (CO + CO ₂ ) (× 100)
(Here, H ₂ , CO, and CO ₂ represent the concentrations of hydrogen, carbon monoxide, and carbon dioxide, respectively, at the reaction tube outlet.)
The results are shown in Tables 1 and 2.

(*): Since the methane conversion rate was already below 40% after 50 hours from the start of the reaction, the reaction was terminated at that point.
A comparison between the catalyst (a) and the catalyst (b) shows that when yttrium is added to the zirconium-cerium composite oxide, the decrease in the methane conversion rate is suppressed and the durability of the catalyst is further improved.

  The comparative catalyst (f) and the comparative catalyst (g) have zirconium oxide: cerium oxide (mass ratio) outside the range defined in the present invention, and methane conversion compared to the catalyst (a) and the catalyst (b) It can be seen that the rate is remarkably lowered and the durability is inferior.

The catalyst ( e ) is a catalyst in which a platinum group element is supported on the entire zirconium-cerium composite oxide and activated alumina. The catalyst (a) and the catalyst (b) have a platinum group element in a part of the activated alumina. It is supported. Further, by comparing the catalyst ( e ) with the catalysts (a) and (b), it is possible to obtain a catalyst excellent in durability because the platinum group element is supported on a part of the activated alumina so that the reduction in methane conversion is less. I understand that However, the durability of the catalyst ( e ) is greatly improved as compared with the comparative catalyst (h) in which zirconium oxide: cerium oxide (mass ratio) is 100: 1.

The catalyst ( c ) has an EPMA average particle diameter of platinum-rhodium-supported active alumina particles of less than 0.5 μm, while the catalyst (a) has the same composition but an EPMA average particle diameter of 4 μm. , The catalyst ( c ) is slightly inferior in durability to the catalyst (a). From this, it can be seen that the EPMA method average particle diameter of the platinum-rhodium supported active alumina particles is 0.5 μm or more, which is superior in durability.

The catalyst ( d ) uses iridium as a platinum group element, and has the same durability as the catalyst (a) and the catalyst (b) using platinum and rhodium.

  Comparison between catalyst (a) and comparative catalyst (i) shows that a mixture of zirconium oxide and cerium oxide is used instead of zirconium-cerium composite oxide. It turns out that a catalyst cannot be obtained.

Further, by comparing the catalyst (a) with the comparative catalyst (j), even if a catalyst component not containing zirconium-cerium composite oxide is supported on a monolith support, the catalyst for partial oxidation having high activity and excellent durability. It can be seen that cannot be obtained.

Claims (4)

A catalyst for partial oxidation of hydrocarbon, comprising a monolithic carrier supporting a catalyst component containing (A) a platinum group element, (B) a zirconium-cerium composite oxide and (C) a refractory inorganic oxide, ) Is supported on a part or all of the refractory inorganic oxide (C) in an amount of 0.4 to 40 mass%, and zirconium in the zirconium-cerium composite oxide (B) ratio of the cerium, zirconium oxide _(ZrO 2): as cerium oxide _(CeO 2) (mass ratio), 100: 2-100: 100 der is, the zirconium - as cerium composite oxide further oxide yttrium A sulfur poisoning-resistant hydrocarbon partial oxidation catalyst characterized by containing 0.1 to 15% by mass based on the total mass of component (B) . EPMA method average particle diameter of the sulfur-poisoning resistance according to claim 1, wherein the range of 0.5~20μm hydrocarbon partial oxidation catalyst of a refractory inorganic oxide carrying platinum group element. A hydrogen-containing gas is produced by partially oxidizing hydrocarbons by contacting hydrocarbon, oxygen and a source gas containing sulfur as a catalyst poison with the sulfur-toxic poisoned hydrocarbon partial oxidation catalyst of claim 1. A method for producing a hydrogen-containing gas. The method for producing a hydrogen-containing gas according to claim 3 , wherein the source gas further contains water vapor.