JP4332733B2 - Hydrocarbon cracking catalyst and method for producing hydrogen using the hydrocarbon cracking catalyst - Google Patents

Description

  The present invention is a hydrocarbon cracking catalyst that produces hydrogen by steam reforming a lower hydrocarbon gas mainly composed of methane, and has excellent oxidation resistance and also has excellent catalytic activity even in a reaction at a low temperature. An object of the present invention is to provide a hydrocarbon cracking catalyst that is excellent in coking resistance (coking: a phenomenon in which carbon is deposited) even under low steam.

  In recent years, new energy technologies have been demanded due to environmental problems, and fixed-bed fuel cells that use hydrogen as a raw fuel, which is one of these technologies, can be used as a distributed power source that can produce electric energy efficiently and cleanly for household and industrial use. Are being studied for automobiles and automobiles.

  Steam reforming (SR), partial oxidation (POX), steam reforming (SR) are techniques for obtaining reformed gas mainly composed of hydrogen by reforming raw gas such as lower hydrocarbons mainly composed of methane. ) And partial oxidation (POX) in combination (autothermal reforming). Among such reforming techniques, steam reforming (SR) is a reaction method that can obtain hydrogen with the highest efficiency.

Steam reforming (SR) is performed according to the following reaction formula.
CH ₄ + H ₂ O → 3H ₂ + CO
In general, this reaction is carried out at around 600 ° C. to 800 ° C., and the S / C (water vapor / carbon ratio: Steam / Carbon ratio) is carried out at around 2.5 to 3.5. This reaction is an endothermic reaction, and the higher the temperature, the more the reaction can be promoted.

  Currently, nickel, iron, cobalt, and the like are used as active metal elements in hydrocarbon decomposition catalysts, and platinum, rhodium, ruthenium, iridium, palladium, and the like are used in noble metal systems. Among these, the catalyst which carry | supported the metallic element of nickel and ruthenium is mainly marketed from the high catalyst activity. Since base metal elements are relatively easy to cause carbon deposition, it is necessary to use them under a condition where the water vapor / carbon ratio is higher than that of the theoretical composition. In addition, noble metal elements are less likely to cause carbon deposition even under a low water vapor / carbon ratio. However, since the catalyst is expensive, the price of the fuel cell system using the catalyst becomes very expensive. This may be a factor that hinders the further spread of battery systems.

  As a commercially available catalyst, it is manufactured by spraying a solution containing nickel, which is an inexpensive base metal element, or ruthenium, which is an expensive noble metal element, on a bead-shaped carrier mainly composed of alumina or the like. There is something that is.

  In general, the catalytic properties during hydrogen production are more excellent as the supported active metal is finer, and the nickel-based catalyst obtained by the production method has several metal nickel particle sizes. It is as large as 10 nm, its catalytic activity at low temperature is low, it is weak in coking resistance and oxidation resistance, and it is not such that the deterioration of the catalyst characteristics with time can be remarkably used. Further, the ruthenium-based catalyst obtained by the above-described production method has a high degree of coking resistance because the active metal element is ruthenium, but the size of the supported metal ruthenium particles is as large as several tens of nm. Further, the catalyst activity at low temperature is low and the deterioration of the catalyst characteristics with time due to sintering is remarkable, so that it cannot be used.

  In order to maintain high catalytic activity, it is required that the oxidation of active metals such as nickel and ruthenium is suppressed and the metal state (zero valence) is maintained.

  From these, it is cheaper as a catalyst for cracking hydrocarbons, shows excellent oxidation resistance in terms of function, suppresses carbon deposition (coking) even at a low steam / carbon ratio, and is highly active. In addition, there is a strong demand for a highly durable catalyst.

  Conventionally, platinum, palladium, rhodium, ruthenium, nickel and the like are supported as catalytically active metals on a carrier such as α-alumina, magnesium oxide, and titanium oxide, and are reported as hydrocarbon decomposition catalysts (Patent Documents 1 to 5). ).

Japanese Patent Laid-Open No. 50-4001 JP 2000-503624 A Japanese Patent Laid-Open No. 2003-225566 Japanese Patent Laid-Open No. 11-276893 JP 2003-265963 A

  Patent Documents 1 to 3 describe a catalyst containing magnesium, aluminum, and nickel. However, since nickel is uniformly present in the entire particles constituting the catalyst, it contains a large amount of nickel. is there.

  Further, the technique described in Patent Document 4 has been proposed as the catalyst nickel loading is preferably 0.1 to 10 wt%, but the methane conversion rate is still sufficient particularly when the nickel loading is small. It is difficult.

  The technique of Patent Document 5 carries two components of nickel and ruthenium as catalytic active metals, but is carried by a normal impregnation method, spray method, coating method, etc. The particle diameter becomes large, the catalytic activity at low temperature is lowered, and the oxidation is weak.

  Therefore, the present invention aims to provide a hydrocarbon cracking catalyst that is excellent in oxidation resistance, has excellent catalytic activity even in a reaction at a low temperature, and is extremely excellent in coking resistance even under low steam. To do.

  The technical problem can be achieved by the present invention as follows.

  That is, the present invention includes magnesium, aluminum, and nickel as constituent elements, and is selected from alkali metals (excluding Na), alkaline earth metals (excluding Mg), Zn, Co, Ce, Cr, Fe, and La. A hydrocarbon decomposition catalyst containing one or more elements, wherein the average particle diameter of the metal nickel fine particles is 1 to 10 nm, and the content of metal nickel is 0.1 relative to the hydrocarbon decomposition catalyst. A hydrocarbon cracking catalyst characterized in that the content of metallic nickel is 0.0007 to 0.342 with respect to the total number of moles of all metal ions constituting the hydrocarbon cracking catalyst. There is (Invention 1).

  The present invention also relates to a hydrocarbon decomposition catalyst according to the first aspect of the present invention, which further contains ruthenium (Invention 2).

  Further, the present invention is the hydrocarbon decomposition catalyst of the first or second aspect of the present invention, selected from alkali metals (excluding Na), alkaline earth metals (excluding Mg), Zn, Co, Ce, Cr, Fe, and La. A hydrocarbon cracking catalyst characterized in that the content of one or more elements is 0.1 to 10.0 in a molar ratio to 1 mole of nickel and ruthenium constituting the hydrocarbon cracking catalyst. There is (Invention 3).

  The present invention also provides a method for producing hydrogen by steam reforming a gas mainly comprising lower hydrocarbons, the hydrocarbon cracking catalyst according to any one of the present inventions 1 to 3, the lower hydrocarbon gas and steam. It is the manufacturing method of hydrogen characterized by making it contact (this invention 4).

  The hydrocarbon decomposition catalyst according to the present invention is one or more elements selected from alkali metals (excluding Na), alkaline earth metals (excluding Mg), Zn, Co, Ce, Cr, Fe and La. By containing, the oxidation of nickel and / or ruthenium metal fine particles is suppressed even when exposed to an oxidizing atmosphere, so that the catalyst is excellent in oxidation resistance.

The catalyst for cracking hydrocarbons according to the present invention has metallic nickel and metal ruthenium highly dispersed on the particles constituting the hydrocarbon cracking catalyst in the form of very fine particles. The area in contact with lower hydrocarbons and water vapor increases, and has excellent catalytic activity and excellent oxidation resistance even at relatively low temperatures.
In particular, when metal nickel and metal ruthenium are supported either near the surface of the particles constituting the hydrocarbon cracking catalyst or near the surface of the catalyst molded body obtained by granulating the particles, the metal The area where nickel and metal ruthenium are in contact with lower hydrocarbons and water vapor is further increased, the catalytic activity is further improved, and coking can be suppressed even when steam reforming is performed under low water vapor conditions.

  Furthermore, since the porous carrier contains a large amount of magnesium, it has excellent sulfur poisoning resistance, and therefore has excellent catalytic activity in terms of durability.

  Furthermore, the hydrocarbon decomposition catalyst according to the present invention uses a lower hydrocarbon gas such as methane as a hydrocarbon decomposition catalyst such as autothermal reforming (ATR) or partial oxidation (POX), or a carbon dioxide reforming catalyst. You can also.

  The configuration of the present invention will be described in more detail as follows.

  First, the hydrocarbon cracking catalyst according to the present invention will be described.

  The hydrocarbon decomposition catalyst according to the present invention is one or more elements selected from alkali metals (excluding Na), alkaline earth metals (excluding Mg), Zn, Co, Ce, Cr, Fe and La. (Hereinafter referred to as “foreign metal element”). By supporting the dissimilar metal, oxidation of metallic nickel or metallic nickel and metallic ruthenium can be suppressed. More preferred are Li, K, Zn, Ce, La and the like.

  The content of the dissimilar metal element in the hydrocarbon cracking catalyst according to the present invention is preferably 0.1 to 10 mol with respect to 1 mol in terms of metal with respect to metal nickel and metal ruthenium. When the amount is less than 0.1 mol, the effect of oxidation resistance cannot be obtained sufficiently. On the other hand, when the amount exceeds 10 mol, sintering of metallic nickel and / or ruthenium metal is promoted, resulting in a decrease in catalytic activity.

  The average particle diameter of the metal nickel fine particles of the hydrocarbon cracking catalyst according to the present invention is 10 nm or less, which is optimal for hydrogen production and has excellent catalytic activity at low temperatures. In a catalyst having metallic nickel fine particles having an average particle diameter exceeding 10 nm, the conversion rate of lower hydrocarbons is reduced in steam reforming in which hydrogen is produced by mixing lower hydrocarbon gas mainly composed of methane and water vapor. Furthermore, in the case of a catalyst having metallic nickel fine particles exceeding 10 nm, the coking resistance of the catalyst body is significantly lowered. Preferably it is 9 nm or less, More preferably, it is 8 nm or less. The lower limit of the average particle diameter is about 0.5 nm.

  The content of metallic nickel in the hydrocarbon cracking catalyst according to the present invention is 0.10 to 40 wt% with respect to the catalyst. When the content of metallic nickel is less than 0.10 wt%, the conversion of lower hydrocarbons decreases. When it exceeds 40 wt%, the particle size of the metal nickel fine particles exceeds 10 nm, and the coking resistance is lowered. Preferably it is 0.18-38 wt%.

  The content of metallic nickel in the hydrocarbon cracking catalyst according to the present invention is indicated by a molar ratio (Ni / total metal ions) to the total number of moles of magnesium, aluminum, ruthenium, nickel and different metal elements contained in the catalyst. The case is 0.0007 to 0.342. When the molar ratio exceeds 0.342, the average particle diameter of the metallic nickel fine particles exceeds 10 nm, so that the conversion rate of lower hydrocarbons at low temperatures is lowered and the coking resistance is lowered. More preferably, it is 0.001-0.34, and still more preferably 0.0015-0.34.

  The hydrocarbon decomposition catalyst according to the present invention may further contain metal ruthenium.

  The average particle diameter of the metal ruthenium fine particles of the hydrocarbon cracking catalyst according to the present invention is preferably 10 nm or less, which is optimal for hydrogen production and has excellent catalytic activity at low temperatures. Catalysts with metal ruthenium fine particles with an average particle diameter exceeding 10 nm have a lower conversion rate of lower hydrocarbons at low temperatures in steam reforming in which hydrogen is produced by mixing lower hydrocarbon gas mainly composed of methane and water vapor. Resulting in. Preferably it is 9 nm or less, More preferably, it is 8 nm or less. The lower limit of the average particle diameter is about 0.5 nm.

  The content of metal ruthenium in the hydrocarbon cracking catalyst according to the present invention is preferably 0.025 to 5.0 wt% with respect to the catalyst. When the content of metal ruthenium is less than 0.025 wt% or 5.0 wt% or more, the conversion rate of lower hydrocarbons at low temperatures decreases. Preferably it is 0.025 to 4.8 wt%.

  The content of metal ruthenium in the hydrocarbon cracking catalyst according to the present invention is indicated by the molar ratio (Ru / total metal ions) to the total number of moles of magnesium, aluminum, nickel, ruthenium and different metal elements contained in the catalyst. In the case, 0.0001 to 0.025 is preferable. When the molar ratio exceeds 0.025, the average particle diameter of the metal ruthenium fine particles exceeds 10 nm, so that the conversion rate of lower hydrocarbons at a low temperature decreases. Preferably it is 0.0001-0.022, More preferably, it is 0.0001-0.020.

  The number of moles of metal ruthenium in the hydrocarbon cracking catalyst according to the present invention is preferably 0.0004 to 30 relative to the number of moles of metal nickel.

  Although the ratio of magnesium and aluminum in the hydrocarbon cracking catalyst according to the present invention is not particularly limited, it is preferable that the amount of magnesium is larger than that of aluminum, and the molar ratio of magnesium to aluminum is Mg: Al = 4: 1 to 1. 5: 1 is preferred. When magnesium exceeds the above range, it is difficult to easily obtain a molded article having sufficient strength, and when it is less than the above range, it is difficult to obtain the characteristics as a porous carrier.

  In the hydrocarbon cracking catalyst according to the present invention, the nickel metal and the ruthenium metal are preferably present in the vicinity of the particle surface of the particles constituting the hydrocarbon cracking catalyst. Moreover, the hydrocarbon cracking catalyst according to the present invention is preferably granulated and used in the form of a molded body, and metal nickel and metal ruthenium may be present in the vicinity of the surface of the molded body.

  In the hydrocarbon cracking catalyst according to the present invention, the position of the dissimilar metal element is not particularly limited. However, the presence of the dissimilar metal element in the vicinity of metal nickel and metal ruthenium is preferable because the effect of oxidation resistance is high.

The specific surface area of the hydrocarbon cracking catalyst according to the present invention is 7 to 320 m ² / g. If it is less than 7 m ² / g, the conversion rate decreases at a high space velocity. When it exceeds 320 m ² / g, industrial production of the layered double hydroxide particle powder as the catalyst precursor becomes difficult. Preferably it is 20-280 m < ² > / g.

  Next, a method for producing a hydrocarbon cracking catalyst according to the present invention will be described.

  The catalyst for cracking hydrocarbons according to the present invention, after producing a layered double hydroxide particle powder as a precursor, is heated and fired in a temperature range of 400 to 1600 ° C. to form a porous oxide particle powder, , And can be obtained by heat reduction in a temperature range of 700 to 1100 ° C.

  The layered double hydroxide particle powder in the present invention can be obtained by the following one-step reaction or two-step reaction.

  That is, the layered double hydroxide particle powder according to the present invention is a mixture of an alkaline aqueous solution containing anions, a magnesium raw material, an aluminum salt aqueous solution, a nickel raw material (and a ruthenium raw material) and a raw material of a different metal element, and has a pH value of 7 After preparing a mixed solution in the range of 0.0 to 13.0, the mixed solution can be obtained by aging in the temperature range of 50 to 300 ° C. (one-step reaction).

The layered double hydroxide particle powder in the present invention is prepared by mixing an alkaline aqueous solution containing anions, a magnesium raw material, and an aluminum salt aqueous solution to obtain a mixed solution having a pH value in the range of 7.0 to 13.0. The mixed solution is aged in the temperature range of 50 to 300 ° C. to produce layered double hydroxide core particles,
Next, the total number of moles relative to the total number of moles of magnesium and aluminum added to the aqueous suspension containing the layered double hydroxide core particles when the layered double hydroxide core particles are formed. Of magnesium, aluminum, nickel (and ruthenium) and alkali metals (excluding Na), alkaline earth metals (excluding Mg), Zn, Co, Ce, Cr, Fe, After adding an aqueous solution containing one or more elements selected from La, the layered double water is aged in a pH value range of 9.0 to 13.0 and a temperature range of 40 to 300 ° C. Magnesium, aluminum, nickel, ruthenium and alkali metals (excluding Na), alkaline earth metals (excluding Mg), Zn, Co, Ce, Cr, newly added to the surface of the hydroxide core particles e, obtained by performing the growth reaction of the coat forming one or two or more elements selected from La to topotactic (two-step reaction).

  Magnesium, aluminum, nickel, ruthenium, alkali metals (excluding Na), alkaline earth metals (excluding Mg), Zn, Co, Ce, Cr, Fe, and La salts that are water-soluble such as nitrates There is no particular limitation.

  As a magnesium raw material, magnesium oxide, magnesium hydroxide, magnesium oxalate, magnesium sulfate, magnesium sulfite, magnesium nitrate, magnesium chloride, magnesium citrate, basic magnesium carbonate, magnesium benzoate and the like can be used.

  As the aluminum raw material, aluminum oxide, aluminum hydroxide, aluminum acetate, aluminum chloride, aluminum nitrate, aluminum oxalate, basic ammonium aluminum, or the like can be used.

  As the nickel salt raw material, nickel oxide, nickel hydroxide, nickel sulfate, nickel carbonate, nickel nitrate, nickel chloride, nickel benzoate, basic nickel carbonate, nickel formate, nickel citrate, nickel diammonium sulfate, etc. may be used. it can.

  As the ruthenium salt raw material, ruthenium nitrate, ruthenium chloride or the like can be used.

  Examples of alkali metal salt raw materials include lithium oxide, lithium hydroxide, lithium nitrate, lithium sulfate, lithium oxalate, lithium acetate, lithium citrate, lithium benzoate, potassium hydroxide, potassium chloride, potassium nitrate, potassium oxalate, and iodide. Potassium, potassium bicarbonate, potassium bromide, potassium acetate, rubidium chloride, rubidium nitrate, rubidium sulfate, rubidium acetate, rubidium bromide, rubidium iodide, cesium nitrate, cesium sulfate, cesium carbonate, cesium acetate, cesium bromide, iodine Cesium fluoride or the like can be used.

  Alkaline earth metal materials include calcium oxide, calcium hydroxide, calcium carbonate, calcium nitrate, calcium sulfate, calcium acetate, calcium chloride, calcium formate, calcium oxalate, calcium bromide, calcium iodide, strontium oxide, and hydroxide Strontium, strontium sulfate, strontium oxalate, strontium nitrate, strontium chloride, strontium acetate, strontium bromide, strontium iodide, barium oxide, barium hydroxide, barium chloride, barium nitrate, barium sulfate, barium oxalate, barium perchlorate Barium acetate, barium formate, barium bromide, barium iodide, and the like can be used.

  As the zinc raw material, zinc oxide, zinc hydroxide, zinc nitrate, zinc sulfate, basic zinc carbonate, zinc chloride, zinc oxalate, zinc acetate, zinc bromide, zinc iodide and the like can be used.

  As the cobalt raw material, cobalt oxide, cobalt hydroxide, cobalt nitrate, cobalt sulfate, cobalt carbonate, cobalt acetate, cobalt chloride, cobalt formate, cobalt bromide, cobalt iodide and the like can be used.

  As the cerium raw material, cerium oxide, cerium hydroxide, cerium nitrate, cerium sulfate, cerium chloride, cerium perchlorate, cerium oxalate, cerium carbonate, cerium acetate, cerium bromide, cerium iodide and the like can be used.

  As the iron salt raw material, iron oxide, iron hydroxide, iron sulfate, iron nitrate, iron chloride, ammonium iron citrate, iron ammonium oxalate, basic iron acetate and the like can be used.

  As the chromium raw material, chromium nitrate, chromium chloride, chromium iodide, chromium bromide, or the like can be used.

  As the lanthanum raw material, lanthanum oxide, lanthanum hydroxide, lanthanum nitrate, lanthanum sulfate, lanthanum chloride, lanthanum acetate, lanthanum oxalate and the like can be used.

  When the number of moles of the growth reaction with respect to the core particles in the two-stage reaction is less than 0.05, the conversion rate of the lower hydrocarbon is lowered and it is difficult to obtain the effect of the present invention. When it exceeds 0.5, the average particle diameter of the metal nickel fine particles and the metal ruthenium fine particles may increase, and the conversion rate of lower hydrocarbons at low temperatures may decrease, and further, the coking resistance may decrease. Preferably it is 0.10-0.45, More preferably, it is 0.12-0.4.

  When the pH value in the growth reaction during the two-stage reaction is less than 9.0, the magnesium, aluminum, nickel, and ruthenium added during the growth reaction are separated and mixed without forming a coating layer. Thus, the desired catalyst cannot be obtained. When the pH value exceeds 13.0, there is too much elution of aluminum, making it difficult to obtain the target composition. Preferably it is 9.0-12.5, More preferably, it is 9.5-12.0.

  When the reaction temperature in the growth reaction during the two-stage reaction is less than 40 ° C., the magnesium, aluminum, nickel and ruthenium added during the growth reaction are separated and mixed without forming a coating layer. The target catalyst cannot be obtained. When the temperature exceeds 300 ° C., large aluminum hydroxide particles and aluminum hydroxide oxide particles are mixed in addition to the layered double hydroxide particles, and the sintering of the catalytically active metal fine particles is promoted to have desired characteristics. No catalyst body can be obtained. Preferably it is 60-250 degreeC.

  The aging time in the growth reaction during the two-stage reaction is not particularly limited, but is 1 to 80 hours, preferably 3 to 24 hours, and more preferably 5 to 18 hours. If it is less than 1 hour, magnesium, aluminum, nickel and ruthenium added during the growth reaction do not form a sufficient coating layer on the surface of the layered double hydroxide core particles. Growth reactions over 80 hours are not industrial.

  The average plate surface diameter of the layered double hydroxide particle powder that is a precursor of the hydrocarbon decomposition catalyst in the present invention is preferably 0.05 to 0.4 μm. When the average plate surface diameter is less than 0.05 μm, it is difficult to filter and wash and industrial production is difficult. When it exceeds 0.4 μm, it is difficult to produce a catalyst molded body. .

  The crystallite size D006 of the layered double hydroxide particle powder in the present invention is preferably 0.001 to 0.08 μm. When the crystallite size D006 is less than 0.001 μm, the viscosity of the aqueous suspension is very high and industrial production is difficult, and when it exceeds 0.08 μm, it is difficult to produce a catalyst compact. is there. More preferably, it is 0.002-0.07 micrometer.

The specific surface area value of the layered double hydroxide particle powder in the present invention is preferably 3.0 to 300 m ² / g. When the specific surface area value is less than 3.0 m ² / g, it is difficult to produce a catalyst molded body. When the specific surface area value exceeds 300 m ² / g, the viscosity of the aqueous suspension is very high. It is difficult to filter and wash, making it difficult to produce industrially. More preferably, it is 5.0-250 m < ² > / g.

  The content of the different metal element in the layered double hydroxide particle powder in the present invention is preferably 0.1 to 10.0 (molar ratio) with respect to nickel and ruthenium.

  The nickel content of the layered double hydroxide particle powder in the present invention is preferably 0.0057 to 26.463 wt%, more preferably 0.01 to 20 wt% with respect to the entire layered double hydroxide particle powder. is there. Further, the number of moles of nickel content of the layered double hydroxide particle powder is a ratio Ni / (total to the total number of moles of magnesium, aluminum, nickel, ruthenium and different metal elements contained in the layered double hydroxide particle powder. The metal ion) is preferably 0.001 to 0.32, more preferably 0.0015 to 0.3.

  In the present invention, the ruthenium content of the layered double hydroxide particle powder is preferably 0.0013 to 3.328 wt%, more preferably 0.002 to 2.00 wt% with respect to the entire layered double hydroxide particle powder. %. The number of moles of the ruthenium content of the layered double hydroxide particle powder is a ratio Ru / (total to the total number of moles of magnesium, aluminum, nickel, ruthenium and different metal elements contained in the layered double hydroxide particle powder. The metal ion) is preferably 0.0015 to 0.022, more preferably 0.0002 to 0.02.

  The number of moles of ruthenium in the layered double hydroxide particle powder in the present invention is preferably 0.0004 to 30 with respect to the number of moles of nickel.

  The ratio of magnesium to aluminum in the layered double hydroxide particle powder in the present invention is not particularly limited, but the molar ratio of magnesium to aluminum is more preferably Mg: Al = 4: 1 to 1.5: 1.

  The oxide particle powder in the present invention is obtained by firing the layered double hydroxide particle powder at 400 ° C to 1600 ° C. When the firing temperature of the layered double hydroxide particle powder is less than 400 ° C., porous oxide particles cannot be obtained. When the temperature exceeds 1600 ° C., the properties as a porous body carrier deteriorate. Preferably it is 450-1500 degreeC, More preferably, it is 500-1400 degreeC. The firing atmosphere may be oxygen, air, or an inert gas such as nitrogen or argon.

  The firing time of the oxide particle powder in the present invention is not particularly limited, but is preferably 0.5 to 24 hours. If it exceeds 24 hours, it is hard to say that it is industrial. Preferably it is 1 to 10 hours.

  The ruthenium content of the oxide particle powder obtained after firing the layered double hydroxide particle powder in the present invention is preferably 0.025 to 5.0 wt%, more preferably 0.005%, based on the whole oxide particle powder. It is 05-4.0 wt%. Further, the number of moles of ruthenium content of the oxide particle powder and the ratio to the total metal ions are approximately the same as the number of moles and the ratio of the layered double hydroxide particle powder.

  The nickel content of the oxide particle powder obtained after firing the layered double hydroxide particle powder in the present invention is preferably 0.10 to 40 wt%, more preferably 0.18 to the entire oxide particle powder. 35 wt%. Further, the number of moles of nickel content of the oxide particle powder and the ratio to the total metal ions are approximately the same as the number of moles and the mole ratio of the layered double hydroxide particle powder.

The oxide particle powder in the present invention is a porous body, the average plate surface diameter is preferably 0.05 to 0.4 μm, and the specific surface area value is preferably 7.0 to 320 m ² / g.

  The hydrocarbon cracking catalyst according to the present invention can be obtained by reducing the oxide particle powder in the range of 700 ° C to 1100 ° C. When the reduction temperature of the oxide particle powder is lower than 700 ° C., nickel is not metallized, so that the target catalytic activity of the present invention cannot be obtained. When the temperature exceeds 1100 ° C., the sintering of nickel and ruthenium proceeds and the particle size of the metal nickel fine particles and metal ruthenium fine particles increases, so that the conversion rate of lower hydrocarbons at low temperatures is lowered, and further the coking resistance is lowered. Preferably it is 700-950 degreeC. The atmosphere during the reduction is not particularly limited as long as it is a reducing atmosphere such as a gas containing hydrogen. The heat treatment time is not particularly limited, but is preferably 0.5 to 24 hours. If it exceeds 24 hours, no industrial merit can be found. Preferably, it is 1 to 10 hours.

  The powdered catalyst obtained as described above may be molded according to each application to be used. The shape and size are not particularly limited, but may be, for example, a spherical shape, a cylindrical shape, a tubular shape, or a shape applied to a honeycomb body. In general, the size of a catalyst body having a spherical, cylindrical, or tubular shape is preferably about 0.1 to 30 mm. Depending on conditions, the strength and pore distribution density of the molded body may be adjusted by adding various binders such as organic substances and inorganic substances. In the present invention, granulation and molding may be performed before the heat treatment.

  Also known is a method of firing layered double hydroxide particle powder to obtain a composite oxide, and then hydrating the composite oxide with an aqueous solution containing anions to obtain layered double hydroxide particle powder. In the present invention, nickel, ruthenium and different metal elements may be supported by the following manufacturing method. The layered double hydroxide particle powder carrying nickel, ruthenium, and a different metal element may be heat-reduced, if necessary, after heating and firing in the same manner as described above.

  That is, by forming a layered double hydroxide particle powder consisting only of magnesium and aluminum into a porous oxide molded body after firing, and then impregnating it with a solution containing nickel (if necessary, ruthenium) and a different metal element. Alternatively, it may be supported by a method of regenerating a layered double hydroxide particle phase containing nickel and ruthenium in the vicinity of the surface of the porous oxide powder or compact.

  Also, a layered double hydroxide particle powder in which nickel is present on the particle surface is obtained according to the above production method, molded and fired to form a porous oxide molded body, and impregnated with a solution containing ruthenium and a different metal element. Thus, the porous oxide powder or the compact may be supported using a method of regenerating the layered double hydroxide particle phase containing nickel near the surface of the compact and ruthenium near the surface of the compact.

  Also, a layered double hydroxide particle powder in which ruthenium is present on the particle surface is obtained according to the above production method, molded and fired to form a porous oxide molded body, and impregnated with a solution containing nickel and a different metal element Thus, it may be supported by a method of regenerating a layered double hydroxide particle phase containing ruthenium near the surface of the porous oxide powder or molded body and nickel near the surface of the molded body.

  Further, a layered double hydroxide particle powder in which nickel and ruthenium are present on the particle surface is obtained according to the production method, and is molded and fired to form a porous oxide molded body, which further contains nickel, ruthenium and a different metal element. By impregnating with a solution, a porous oxide powder or a method of regenerating a layered double hydroxide particle phase containing nickel and ruthenium near the surface of the molded body and nickel and ruthenium near the surface of the molded body It may be supported.

  Further, a layered double hydroxide particle powder having nickel, ruthenium and different metal elements present on the particle surface is obtained according to the above production method, molded and fired to form a porous oxide molded body, and further contains nickel and ruthenium. By impregnating with a solution, a method of regenerating a layered double hydroxide particle phase containing nickel and ruthenium near the surface of the porous oxide powder or the molded body and nickel and ruthenium near the surface of the molded body is used. It may be supported.

  In addition, a layered double hydroxide particle powder having nickel, ruthenium and different metal elements present on the particle surface is obtained according to the above production method, and molded and fired to obtain a porous oxide molded body. By impregnating a solution containing a metal element, the layered double hydroxide particle phase containing nickel and ruthenium near the surface of the porous oxide powder or the molded body and nickel and ruthenium near the surface of the molded body is regenerated. You may carry | support using a method.

  Next, a hydrogen production method using the hydrocarbon cracking catalyst according to the present invention will be described.

In the method for producing hydrogen using the hydrocarbon decomposition catalyst according to the present invention, the reaction temperature is 400 to 900 ° C., and the molar ratio (S / C) of water vapor to lower hydrocarbon is 1.2 to 6.0. The hydrocarbon decomposition catalyst according to the present invention is brought into contact with lower hydrocarbon gas and water vapor mainly composed of methane under the condition that the space velocity (GHSV) is 500 to 600,000 h ⁻¹ .

  When the reaction temperature is less than 400 ° C., the conversion rate of lower hydrocarbons is low, and when the reaction is carried out for a long time, coking is likely to occur, and the catalytic properties may be deactivated at the end. When it exceeds 900 ° C., lower hydrocarbons such as methane are decomposed. Preferably it is 450-900 degreeC, More preferably, it is 500-850 degreeC.

  When the molar ratio S / C of water vapor to lower hydrocarbon is less than 1.2, the coking resistance is lowered. On the other hand, when S / C exceeds 6.0, a large amount of water vapor is required for hydrogen production, which is expensive and unrealistic. Preferably it is 1.5-6.0, More preferably, it is 1.8-5.0.

Incidentally, the space velocity (GHSV) is preferably 800～300,000H ^-1, more preferably 1,000~200,000h ^-1.

  The lower hydrocarbon gas used for hydrogen production is preferably a hydrocarbon having 1 to 6, preferably 1 to 4 carbon atoms. Such things include, for example, ethane, propane, butane in addition to methane.

  The hydrocarbon cracking catalyst according to the present invention has sufficient catalytic activity, durability and resistance even when it is switched to steam reforming after being started by autothermal reforming reaction, or even when steam reforming is performed for a long time. It is an optimum catalyst in a fuel cell system that can exhibit caulking properties and sulfur poisoning resistance and introduces DSS (Daily start-up shut-down).

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The reason why the hydrocarbon cracking catalyst according to the present invention is excellent in oxidation resistance and has an excellent catalytic activity is not yet clear, but the present inventor estimates as follows.

  The hydrocarbon cracking catalyst according to the present invention is one or two selected from the group consisting of different metal elements (alkali metal (excluding Na), alkaline earth metal (excluding Mg), Zn, Co, Ce, Cr, Fe, La). In the case where the metal nickel fine particles and / or the metal ruthenium fine particles are oxidized, the dissimilar metal element is oxidized or the metal nickel and the metal ruthenium are supported even when exposed to an oxidizing atmosphere. The present inventors presume that the catalyst is excellent in oxidation resistance because the metal and the dissimilar metal element are alloyed and are not easily oxidized, so that the oxidation of metal nickel and / or metal ruthenium is suppressed. As a result, a high C1 conversion can be maintained even for a long-time reaction.

The catalyst for cracking hydrocarbons according to the present invention has excellent catalytic activity because metallic nickel is supported on particles constituting the catalyst with particles as fine as 1 to 10 nm, which is unprecedented.
In particular, when the metal nickel fine particles are supported either near the particle surface of the particles constituting the catalyst or near the surface of the molded catalyst obtained by granulation, the lower hydrocarbon gas is efficiently used in the hydrocarbon decomposition reaction. Since it can be well brought into contact with nickel and ruthenium, the catalytic activity is further improved.

  In the hydrocarbon cracking catalyst according to the present invention, metal ruthenium is also supported on particles constituting the catalyst with particles as fine as 1 to 10 nm as never before, so that the lower hydrocarbon gas is efficiently used in the hydrocarbon cracking reaction. It can be contacted with nickel and ruthenium and has excellent catalytic activity.

  In addition, as described above, the hydrocarbon cracking catalyst according to the present invention has high catalytic activity and is excellent in coking resistance even under low steam and can exhibit high catalytic activity.

  A typical embodiment of the present invention is as follows.

  The plate surface diameter of the layered double hydroxide particle powder is the average value of the measured values using “electron micrograph TEM1200EX (manufactured by JEOL Ltd.)” (acceleration voltage: 100 kV).

  D006 (particle thickness) of the layered double hydroxide particle powder is “X-ray diffractometer RINT-2500 (manufactured by Rigaku Corporation)” (tube: Cu, tube voltage: 40 kV, tube current: 300 mA, Layered double water using a goniometer: wide angle goniometer, sampling width: 0.020 °, scanning speed: 2 ° / min, diverging slit: 1 °, scattering slit: 1 °, light receiving slit: 0.50 mm) This is a value calculated using the Scherrer equation from the diffraction peak curve of the D006 crystal plane of the oxide particle powder.

  Identification of the layered double hydroxide particle powder was performed by X-ray diffraction measurement. X-ray diffraction measurement was performed using the X-ray diffractometer at a diffraction angle 2θ of 3 to 80 °.

  The size of the particles of metallic nickel and metallic ruthenium is indicated by the average value of the numerical values measured from the electron micrograph. The size of the metal fine particles exceeding 10 nm is “X-ray diffractometer RINT-2500 (manufactured by Rigaku Corporation)” (tube: Cu, tube voltage: 40 kV, tube current: 300 mA, goniometer: wide angle goniometer. , Sampling width: 0.020 °, scanning speed: 2 ° / min, diverging slit: 1 °, scattering slit: 1 °, light receiving slit: 0.50 mm), and the size of the fine particles using Scherrer's equation Was calculated. The particle sizes of metallic nickel and metallic ruthenium obtained from this X-ray diffractometer were the same as those obtained from the electron micrograph.

  The content of magnesium, aluminum, nickel, ruthenium, alkali metal, alkaline earth metal (excluding Mg), Zn, Co, Ce, Cr, Fe, La constituting the catalyst is determined by dissolving the catalyst with an acid. Plasma emission spectroscopy analyzer SPS4000 (Seiko Electronics Co., Ltd.) "

  The BET specific surface area value is the B.B. E. T.A. Measured by the method.

  The amount of carbon deposited during the steam reforming reaction was determined by measuring the amount of carbon in the catalyst body before and after the catalytic reaction with a carbon sulfur measuring device.

  A typical embodiment of the present invention is as follows.

Example 1 <Preparation of hydrocarbon catalyst>
104.4 g of MgSO ₄ · 7H ₂ O and 34.32 g of Al ₂ (SO ₄ ) ₃ · 8H ₂ O were dissolved in water to make 1000 ml. Separately, a 1000 ml solution in which 13.12 g of NaCO ₃ was dissolved was added to 286.1 ml of NaOH (14 mol / L concentration) to prepare a total amount of 2000 ml of an alkali mixed solution. A mixed solution of the magnesium salt and aluminum salt was added to the alkali mixed solution, and aging was performed at 80 ° C. for 8 hours to obtain layered double hydroxide core particles. The pH of the reaction solution at this time was 11.8.
Next, 26.35 g of MgSO ₄ .7H ₂ O, 24.36 g of NiSO ₄ .6H ₂ O, 8.667 g of Al ₂ (SO ₄ ) ₃ .8H ₂ O and 13.29 g of LiNO _{3 were} added to this alkaline suspension. 500 ml of a mixed solution of magnesium salt, nickel salt, aluminum salt and lithium salt dissolved in the solution was added to adjust the pH of the reaction solution to 11.1 and further aged at 95 ° C. for 12 hours, to form the layered double hydroxide core. It was made topotactically grow on the particle surface to obtain layered double hydroxide particles. The total number of moles of magnesium, aluminum, nickel, and lithium added during the growth reaction was 0.294 with respect to the total number of moles of the magnesium and aluminum added during the formation of the core particles. The average plate surface diameter of the layered double hydroxide particles obtained here was 0.215 μm, the crystallite size D006 was 0.054 μm, and the BET was 53.1 m ² / g.

  The layered double hydroxide particle powder thus obtained was molded into spherical beads having a diameter of 3 mm. After calcining in air at 800 ° C. for 12 hours to obtain oxide particle powder, reduction treatment is performed at 800 ° C. for 1 hour in a gas stream with a hydrogen / argon volume ratio of 20/80, and the catalyst for hydrocarbon decomposition Got. The content of nickel in the obtained catalyst was 14.63 wt% (Ni / total metal ions = 0.093 (molar ratio)), and the size of the metal nickel fine particles was 2 nm. The content of lithium in the obtained catalyst was Li / Ni = 2.081. The metal nickel particles and metal ruthenium are presumed to exist only near the particle surface.

<Hydrogen production reaction using hydrocarbon catalyst>
Evaluation of the catalyst for hydrocarbon was made by filling a catalyst tube with 20 to 50 g in a stainless steel reaction tube having a diameter of 20 mm.
Through this catalyst tube (reactor), city gas 13A and water vapor were circulated as a raw material gas at a reaction pressure of 0.5 MPa, a reaction temperature of 400 ° C. to 1000 ° C., and a space velocity of 50000 h ⁻¹ . The water vapor / carbon ratio (S / C) at this time is 1.5 or 3.0.

The methane conversion shown in the table is calculated from the following formula.
Methane conversion rate (%) = (1-outlet methane concentration / inlet methane concentration) × 100

The reaction results are shown in Tables 1 to 3.
Table 1 shows the relationship between the reaction temperature (400 ° C. to 1000 ° C.) and the methane conversion rate when the reaction is conducted for 24 hours at GHSV of 50000 h ⁻¹ and steam / carbon (S / C) of 3.0.
Table 2 shows the relationship between the reaction time and the methane conversion rate when GHSV is 50000 h ⁻¹ , the reaction temperature is 700 ° C., and the water vapor / carbon (S / C) is 1.5 and 3.0.
Table 3 shows the relationship between the reaction time when the GHSV is 50000 h ⁻¹ , the reaction temperature is 700 ° C., and the water vapor / carbon (S / C) is 1.5, and the amount of carbon deposited before and after the measurement of catalytic activity.

<Example 2>
MgCl ₂ · 6H ₂ O 103.3 g, AlCl ₃ · 6H ₂ O 24.53 g, NiCl ₂ · 6H ₂ O 82.76 g, RuCl ₃ 0.03 g and LiNO ₃ 12.61 were dissolved in water to make 1000 ml. Separately, a 1000 ml solution in which 15.08 g of NaCO ₃ was dissolved was added to 326 ml of NaOH (14 mol / L concentration) to prepare an alkaline mixed solution of 2000 ml in total. The mixed solution of the magnesium salt, aluminum salt, nickel salt, ruthenium salt and lithium salt was added to the alkali mixed solution, and aging was carried out at 90 ° C. for 12 hours to obtain layered double hydroxide particles. The pH of the reaction solution at this time was 12.8. The layered double hydroxide particles thus obtained had an average plate surface diameter of 0.284 μm, a crystallite size D006 of 0.068 μm, and a BET of 8.5 m ² / g.

  The layered double hydroxide particle powder thus obtained was molded into spherical beads having a diameter of 3 mm. After calcining in air at 1150 ° C. for 8 hours to obtain oxide particle powder, reduction treatment is performed in a gas stream having a hydrogen / argon volume ratio of 20/80 at 720 ° C. for 4 hours, and a catalyst for hydrocarbon decomposition Got. The content of nickel in the obtained catalyst was 39.39 wt% (Ni / (total metal ions) = 0.285 (molar ratio)), and the size of the metal nickel fine particles was 8 nm. The ruthenium content in the obtained catalyst was 0.027 wt% (Ru / (total metal ions) = 0.0001 (molar ratio)), and the size of the metal ruthenium fine particles was 3 nm. The content of lithium in the obtained catalyst was Li / (Ni + Ru) = 0.514 (molar ratio).

<Example 3>
102.5 g of MgCl ₂ · 6H ₂ O and 30.43 g of AlCl ₃ · 6H ₂ O were dissolved in water to make 1000 ml. Separately, a 1000 ml solution in which 19.48 g of NaCO ₃ was dissolved was added to 346 ml of NaOH (14 mol / L concentration) to prepare an alkaline mixed solution of 2000 ml in total. The mixed solution of the magnesium salt and the aluminum salt was added to the alkali mixed solution and aged at 174 ° C. for 3 hours to obtain layered double hydroxide core particles. The pH of the reaction solution at this time was 11.5.
Next, this alkaline suspension was mixed with 4.223 g of MgCl ₂ .6H ₂ O, 24.16 g of NiCl ₂ .6H ₂ O, 1.254 g of AlCl ₃ .6H ₂ O, 0.215 g of Ru (NO ₃ ) ₃ and LiNO. ₃ Add 500 ml of a mixed solution of magnesium salt, nickel salt, aluminum salt, ruthenium salt and potassium salt dissolved in 14.32 g, bring the pH of the reaction solution to 10.8, and further aged at 230 ° C. for 15 hours. It was made topotactically grow on the surface of the double hydroxide core particles to obtain layered double hydroxide particles. The total number of moles of magnesium, aluminum, nickel, ruthenium, and lithium added during the growth reaction was 0.313 with respect to the total number of moles of magnesium and aluminum added during the formation of the core particles. The layered double hydroxide particles obtained here had an average plate surface diameter of 0.212 μm, a crystallite size D006 of 0.065 μm, and a BET of 18.2 m ² / g.

  The layered double hydroxide particle powder thus obtained was molded into spherical beads having a diameter of 3 mm. After calcination in air at 910 ° C. for 8 hours to obtain oxide particle powder, reduction treatment is performed at 870 ° C. in a gas stream with a hydrogen / argon volume ratio of 20/80 for 6 hours, and a hydrocarbon decomposition catalyst Got. The content of nickel in the obtained catalyst was 6.095 wt% (Ni / (total metal ions) = 0.094 (molar ratio)), and the size of the metal nickel fine particles was 3 nm. The ruthenium content in the obtained catalyst was 0.105 wt% (Ru / (total metal ions) = 0.0009 (molar ratio)), and the size of the metal ruthenium fine particles was 3 nm. The content of lithium in the obtained catalyst was Li / (Ni + Ru) = 4.934 (molar ratio). The metal nickel particles and metal ruthenium are presumed to exist only near the particle surface.

<Example 4>
MgCl ₂ · 6H ₂ O (95.29 g) and AlCl ₃ · 6H ₂ O (22.63 g) were dissolved in water to make 1000 ml. Separately, to 168 ml of NaOH (14 mol / L concentration), a 1000 ml solution in which 18.08 g of NaCO ₃ was dissolved was added to prepare an alkaline mixed solution of 2000 ml in total. The mixed solution of the magnesium salt and the aluminum salt was added to the alkali mixed solution and aged at 60 ° C. for 3 hours to obtain layered double hydroxide core particles. The pH of the reaction solution at this time was 10.5.
Then, this alkaline _suspension, MgCl ₂ · 6H ₂ O _28.54g and NiCl ₂ · _{6H 2} O 0.196g and AlCl ₃ · _6H 2 O 6.780g and _{Ru (NO} 3) 3 _6.140g and KCl Add 500 ml of a mixed solution of magnesium salt, nickel salt, aluminum salt, ruthenium salt and potassium salt dissolved in 8.159 g, bring the pH of the reaction solution to 10.2, and further aged at 120 ° C. for 8 hours. It was made topotactically grow on the surface of the hydroxide core particles to obtain layered double hydroxide particles. The total number of moles of magnesium, aluminum, nickel, ruthenium and potassium added during the growth reaction was 0.250 with respect to the total number of moles of magnesium and aluminum added during the formation of the core particles. The layered double hydroxide particles thus obtained had an average plate surface diameter of 0.154 μm, a crystallite size D006 of 0.038 μm, and a BET of 98.2 m ² / g.

  The layered double hydroxide particle powder thus obtained was molded into spherical beads having a diameter of 3 mm. After calcining in air at 1580 ° C. for 24 hours to form oxide particles, reduction treatment is performed at 1000 ° C. in a gas stream with a hydrogen / argon volume ratio of 20/80 for 3 hours to obtain a hydrocarbon cracking catalyst. Got. The content of nickel in the obtained catalyst was 0.114 wt% (Ni / (total metal ions) = 0.001 (molar ratio)), and the size of the metal nickel fine particles was 3 nm. The ruthenium content in the obtained catalyst was 4.963 wt% (Ru / (total metal ions) = 0.022 (molar ratio)), and the size of the metal ruthenium fine particles was 2 nm. The content of potassium in the obtained catalyst was K / (Ni + Ru) = 4.934 (molar ratio). The metal nickel particles and metal ruthenium are presumed to exist only near the particle surface.

<Example 5>
194.4 g of MgSO ₄ · 7H ₂ O and 70.59 g of Al ₂ (SO ₄ ) ₃ · 8H ₂ O were dissolved in water to make 1000 ml. Separately, a 1000 ml solution in which 26.32 g of NaCO ₃ was dissolved was added to 296.5 ml of NaOH (14 mol / L concentration) to prepare a total amount of 2000 ml of an alkali mixed solution. A mixed solution of the magnesium salt and aluminum salt was added to the alkali mixed solution, and aging was performed at 75 ° C. for 4 hours to obtain layered double hydroxide core particles. The pH of the reaction solution at this time was 11.2.
Subsequently, 38.63 g of MgSO ₄ · 7H ₂ O, 34.62 g of NiSO ₄ · 6H ₂ O, 15.25 g of Al ₂ (SO ₄ ) ₃ · 8H ₂ O and Ru (NO ₃ ) _{3 were} added to this alkaline suspension. 500 ml of a mixed solution of magnesium salt, nickel salt, aluminum salt, ruthenium salt and calcium salt in which 2.526 g and CaSO ₄ · 2H ₂ O (25.08 g) were dissolved was added to adjust the pH of the reaction solution to 9.1, and 91 Aging was carried out at 18 ° C. for 18 hours, and the layered double hydroxide core particles were grown on the surface of the layered double hydroxide core particles to obtain layered double hydroxide particles. The total number of moles of magnesium, aluminum, nickel, ruthenium, and calcium added during the growth reaction was 0.435 with respect to the total number of moles of the magnesium and aluminum added during the formation of the core particles. The average plate surface diameter of the layered double hydroxide particles obtained here was 0.184 μm, the crystallite size D006 was 0.052 μm, and the BET was 84.4 m ² / g.

  The layered double hydroxide particle powder thus obtained was molded into spherical beads having a diameter of 3 mm. After calcining in air at 1320 ° C. for 2 hours to obtain oxide particle powder, reduction treatment is carried out at 950 ° C. in a gas stream having a hydrogen / argon volume ratio of 20/80 for 10 hours, and a hydrocarbon decomposition catalyst Got. The content of nickel in the obtained catalyst was 10.97 wt% (Ni / (total metal ions) = 0.083 (molar ratio)), and the size of the metal nickel fine particles was 5 nm. The content of ruthenium in the obtained catalyst was 1.259 wt% (Ru / (total metal ions) = 0.006 (molar ratio)), and the size of the metal ruthenium fine particles was 1 nm. The content of calcium in the obtained catalyst was Ca / (Ni + Ru) = 1.037 (molar ratio). The metal nickel particles and metal ruthenium are presumed to exist only near the particle surface.

<Example 6>
69.36 g of MgSO ₄ .7H ₂ O, 27.37 g of Al ₂ (SO ₄ ) ₃ .8H ₂ O, 5.919 g of NiSO ₄ .6H ₂ O, 0.701 g of RuCl _{3 and} 73.90 of ZnSO ₄ .7H ₂ O Was dissolved in water to make 1000 ml. Separately, 1000 ml of a solution in which 8.301 g of NaCO ₃ was dissolved was added to 43.01 ml of NaOH (14 mol / L concentration) to prepare a total amount of 2000 ml of an alkali mixed solution. The mixed solution of the magnesium salt, aluminum salt, nickel salt, ruthenium salt and zinc salt was added to the alkali mixed solution and aged at 58 ° C. for 16 hours to obtain layered double hydroxide particles. The pH of the reaction solution at this time was 7.2.
The average plate surface diameter of the layered double hydroxide particles obtained here was 0.051 μm, the crystallite size D006 was 0.001 μm, and the BET was 298.3 m ² / g.

  The layered double hydroxide particle powder thus obtained was molded into spherical beads having a diameter of 3 mm. After calcining in air at 450 ° C. for 18 hours to form oxide particle powder, reduction treatment is carried out for 12 hours in a gas stream having a hydrogen / argon volume ratio of 20/80 at 880 ° C. Got. The content of nickel in the obtained catalyst was 3.777 wt% (Ni / (total metal ions) = 0.034 (molar ratio)), and the size of the metal nickel fine particles was 7 nm. The ruthenium content in the obtained catalyst was 0.976 wt% (Ru / (total metal ions) = 0.005 (molar ratio)), and the size of the metal ruthenium fine particles was 2 nm. The content of zinc in the obtained catalyst was Zn / (Ni + Ru) = 9.592 (molar ratio).

<Example 7>
Mg (NO ₃ ) ₂ · 6H ₂ O 226.7 g and Al (NO ₃ ) ₃ · 9H ₂ O 59.23 g were dissolved in water to make 1000 ml. Separately, a 1000 ml solution in which 26.40 g of NaCO ₃ was dissolved was added to 495.9 ml of NaOH (14 mol / L concentration) to prepare a total amount of 2000 ml of an alkali mixed solution. The mixed solution of the magnesium salt and aluminum salt was added to the alkali mixed solution, and aging was performed at 150 ° C. for 4 hours to obtain layered double hydroxide core particles. The pH of the reaction solution at this time was 12.9.
Then, this alkaline _{suspension, Mg (NO 3) 2 ·} 6H 2 O 26.64g and _{Ni (NO 3) 2 · 6H} 2 O 93.05g and _{Al (NO 3) 3 · 9H} 2 O 7.503g and _{Ru (NO} 3) 3 _5.754g and _{Ce (NO 3) 3 · 6H} 2 O 16.03 a mixed solution of a magnesium salt and nickel salt and an aluminum salt and ruthenium salt and a cerium salt 500ml dissolved, and the reaction The pH of the solution was adjusted to 11.9, and further aged at 292 ° C. for 2 hours to grow topologically on the surface of the layered double hydroxide core particles to obtain layered double hydroxide particles. The total number of moles of magnesium, aluminum, nickel, ruthenium, and cerium added during the growth reaction was 0.167 with respect to the total number of moles of magnesium and aluminum added during the formation of the core particles. The layered double hydroxide particles thus obtained had an average plate surface diameter of 0.395 μm, a crystallite size D006 of 0.079 μm, and a BET of 3.2 m ² / g.

  The layered double hydroxide particle powder thus obtained was molded into spherical beads having a diameter of 3 mm. After calcination in air at 720 ° C. for 10 hours to obtain oxide particle powder, reduction treatment is carried out at 1050 ° C. in a gas stream with a hydrogen / argon volume ratio of 20/80 for 16 hours, and a hydrocarbon decomposition catalyst Got. The content of nickel in the obtained catalyst was 22.42 wt% (Ni / (total metal ions) = 0.186 (molar ratio)), and the size of the metal nickel fine particles was 1 nm. The content of ruthenium in the obtained catalyst was 2.413 wt% (Ru / (total metal ions) = 0.012 (molar ratio)), and the size of the metal ruthenium fine particles was 4 nm. The content of cerium in the obtained catalyst was 0.109 (molar ratio). The metal nickel particles and metal ruthenium are presumed to exist only near the particle surface.

<Example 8>
Mg (NO ₃ ) ₂ · 6H ₂ O 88.65 g and Al (NO ₃ ) ₃ · 9H ₂ O 29.47 g were dissolved in water to make 1000 ml. Separately, a 1000 ml solution in which 13.38 g of NaCO ₃ was dissolved was added to 259.2 ml of NaOH (14 mol / L concentration) to prepare an alkaline mixed solution of 2000 ml in total. A mixed solution of the magnesium salt and aluminum salt was added to the alkali mixed solution, and aging was performed at 95 ° C. for 8 hours to obtain layered double hydroxide core particles. The pH of the reaction solution at this time was 9.8.
Subsequently, 14.86 g of Mg (NO ₃ ) ₂ .6H ₂ O, 20.22 g of Ni (NO ₃ ) ₂ .6H ₂ O and 4.347 g of Al (NO ₃ ) ₃ .9H ₂ O were added to this alkaline suspension. and RuCl ₃ 1.876g and LaCl ₃ · _7H 2 O 13.29g a mixed solution of a magnesium salt and nickel salt and an aluminum salt and ruthenium salt and lanthanum salt 500ml dissolved was added, the pH of the reaction solution to 9.5 Further, aging was performed at 75 ° C. for 12 hours, and the layered double hydroxide core particles were grown on the surface of the layered double hydroxide core particles to obtain layered double hydroxide particles. The total number of moles of magnesium, aluminum, nickel, ruthenium, and lanthanum added during the growth reaction was 0.333 with respect to the total number of moles of the magnesium and aluminum added during the formation of the core particles. The average plate surface diameter of the layered double hydroxide particles obtained here was 0.105 μm, the crystallite size D006 was 0.022 μm, and the BET was 215.3 m ² / g.

  The layered double hydroxide particle powder thus obtained was molded into spherical beads having a diameter of 3 mm. After calcination in air at 650 ° C. for 1 hour to obtain oxide particle powder, reduction treatment is carried out at 980 ° C. in a gas stream with a hydrogen / argon volume ratio of 20/80 for 7 hours, and a hydrocarbon decomposition catalyst Got. The content of nickel in the obtained catalyst was 11.61 wt% (Ni / (total metal ions) = 0.1 (molar ratio)), and the size of the metal nickel fine particles was 3 nm. The ruthenium content in the obtained catalyst was 1.865 wt% (Ru / (total metal ions) = 0.0009 (molar ratio)), and the size of the metal ruthenium fine particles was 3 nm. The content of lanthanum in the obtained catalyst was La / (Ni + Ru) = 0.471 (molar ratio). The metal nickel particles and metal ruthenium are presumed to exist only near the particle surface.

<Example 9>
167.2 g of MgSO ₄ · 7H ₂ O and 43.41 g of Al ₂ (SO ₄ ) ₃ · 8H ₂ O were dissolved in water to make 1000 ml. Separately, a 1000 ml solution in which 15.56 g of NaCO ₃ was dissolved was added to 157.8 ml of NaOH (14 mol / L concentration) to prepare an alkaline mixed solution of 2000 ml in total. A mixed solution of the magnesium salt and aluminum salt was added to the alkali mixed solution, and aging was carried out at 210 ° C. for 19 hours to obtain layered double hydroxide core particles. The pH of the reaction solution at this time was 10.2.
Next, 19.21 g of MgSO ₄ .7H ₂ O, 5.739 g of NiSO ₄ .6H ₂ O, 7.583 g of Al ₂ (SO ₄ ) ₃ .8H ₂ O, and 2.459 g of RuCl _{3 were} added to this alkaline suspension. 500 ml of a mixed solution of magnesium salt, nickel salt, aluminum salt, ruthenium salt, lithium salt and cerium salt dissolved in 11.28 g of Li ₂ SO ₄ .H ₂ O and 5.705 g of Ce (ClO ₄ ) ₃ .8H ₂ O The reaction solution was adjusted to pH 10.1 and further aged at 180 ° C. for 4 hours to grow topologically on the surface of the layered double hydroxide core particles to obtain layered double hydroxide particles. . Note that the total number of moles of magnesium, aluminum, nickel, ruthenium, lithium and cerium added during the growth reaction was 0.143 with respect to the total number of moles of magnesium and aluminum added during the formation of the core particles. It was. The average plate surface diameter of the layered double hydroxide particles obtained here was 0.32 μm, the crystallite size D006 was 0.071 μm, and the BET was 10.2 m ² / g.

  The layered double hydroxide particle powder thus obtained was molded into spherical beads having a diameter of 3 mm. After calcination in air at 930 ° C. for 22 hours to obtain oxide particle powder, reduction treatment is carried out at 850 ° C. in a gas stream having a hydrogen / argon volume ratio of 20/80 for 20 hours, and a hydrocarbon decomposition catalyst Got. The content of nickel in the obtained catalyst was 2.807 wt% (Ni / (total metal ions) = 0.02 (molar ratio)), and the size of the metal nickel fine particles was 6 nm. The content of ruthenium in the obtained catalyst was 2.624 wt% (Ru / (total metal ions) = 0.011 (molar ratio)), and the size of the metal ruthenium fine particles was 6 nm. The content of lithium in the obtained catalyst is Li / (Ni + Ru) = 2.618. The content of cerium was Ce / (Ni + Ru) = 0.291. The metal nickel particles and metal ruthenium are presumed to exist only near the particle surface.

<Example 10>
MgCl ₂ · 6H ₂ O 74.33 g and AlCl ₃ · 6H ₂ O 15.22 g were dissolved in water to make 1000 ml. Separately, a 1000 ml solution in which 12.35 g of NaCO ₃ was dissolved was added to 202.6 ml of NaOH (14 mol / L concentration) to prepare an alkaline mixed solution of 2000 ml in total. A mixed solution of the magnesium salt and aluminum salt was added to the alkali mixed solution, and aging was performed at 120 ° C. for 8 hours to obtain layered double hydroxide core particles. The pH of the reaction solution at this time was 10.6.
Next, MgCl ₂ .6H ₂ O 20.54 g, NiCl ₂ .6H ₂ O 75.22 g, AlCl ₃ .6H ₂ O 4.877 g, RuCl ₃ 1.046 g and KCl 13.32 g were added to this alkaline suspension. _{la (NO 3) 3 · 6H} 2 O 25.79g a mixed solution of a magnesium salt and nickel salt and an aluminum salt and ruthenium salt and potassium salt and lanthanum salt 500ml dissolved was added, and the pH of the reaction solution 10.1 Further, aging was carried out at 180 ° C. for 4 hours, and the layered double hydroxide particles were grown on the surface of the layered double hydroxide core particles to obtain layered double hydroxide particles. The total number of moles of magnesium, aluminum, nickel, ruthenium, potassium, and lanthanum added during the growth reaction was 0.454 with respect to the total number of moles of magnesium and aluminum added during the formation of the core particles. It was. The layered double hydroxide particles thus obtained had an average plate surface diameter of 0.162 μm, a crystallite size D006 of 0.043 μm, and a BET of 101.5 m ² / g.

  The layered double hydroxide particle powder thus obtained was molded into spherical beads having a diameter of 3 mm. After calcining in air at 1050 ° C. for 13 hours to obtain oxide particle powder, reduction treatment is performed at 780 ° C. in a gas stream having a hydrogen / argon volume ratio of 20/80 for 8 hours, and the catalyst for hydrocarbon decomposition Got. The content of nickel in the obtained catalyst was 30.68 wt% (Ni / (total metal ions) = 0.27 (molar ratio)), and the size of the metal nickel fine particles was 9 nm. The ruthenium content in the obtained catalyst was 0.594 wt% (Ru / (total metal ions) = 0.003 (molar ratio)), and the size of the metal ruthenium fine particles was 2 nm. The content of potassium in the obtained catalyst was K / (Ni + Ru) = 0.547, and the content of lanthanum was La / (Ni + Ru) = 0.182. The metal nickel particles and metal ruthenium are presumed to exist only near the particle surface.

<Example 11>
MgSO ₄ · _7H 2 O 94.51g and _{Al 2 (SO 4) 3 ·} 8H 2 O 37.29g and NiSO ₄ · _6H 2 O 4.033g and RuCl ₃ 2.207g and LiNO ₃ 14.27 and Zn (NO _{3) 3} · _6H 2 O _47.33g was a 1000ml dissolved in water. Separately, a 1000 ml solution in which 11.38 g of NaCO ₃ was dissolved was added to 22.12 ml of NaOH (14 mol / L concentration) to prepare an alkaline mixed solution of 2000 ml in total. The mixed solution of the magnesium salt and the aluminum salt was added to the alkali mixed solution and aged at 295 ° C. for 1 hour to obtain layered double hydroxide particles. The pH of the reaction solution at this time was 8.4.
The layered double hydroxide particles obtained here had an average plate surface diameter of 0.085 μm, a crystallite size D006 of 0.012 μm, and a BET of 242.2 m ² / g.

  The layered double hydroxide particle powder thus obtained was molded into spherical beads having a diameter of 3 mm. After calcining in air at 880 ° C. for 23 hours to obtain oxide particle powder, reduction treatment was performed at 890 ° C. in a gas stream having a hydrogen / argon volume ratio of 20/80 for 11 hours to obtain a hydrocarbon cracking catalyst. Got. The content of nickel in the obtained catalyst was 2.068 wt% (Ni / (total metal ions) = 0.177 (molar ratio)), and the size of the metal nickel fine particles was 2 nm. The ruthenium content in the obtained catalyst was 1.781 wt% (Ru / (total metal ions) = 0.008 (molar ratio)), and the size of the metal ruthenium fine particles was 5 nm. The content of zinc in the obtained catalyst was Zn / (Ni + Ru) = 8.995, and the content of lithium was Li / (Ni + Ru) = 6.919.

<Reference Example 1>
199.7 g of MgSO ₄ · 7H ₂ O, 78.84 g of Al ₂ (SO ₄ ) ₃ · 8H ₂ O, 170.5 g of NiSO ₄ · 6H ₂ O and 3.364 g of RuCl ₃ were dissolved in water to make 1000 ml. Separately, a 1000 ml solution in which 24.07 g of NaCO ₃ was dissolved was added to 595.0 ml of NaOH (14 mol / L concentration) to prepare an alkaline mixed solution of 1000 ml in total.
The mixed solution of the above magnesium salt and aluminum salt was added to this alkali mixed solution and aged at 132 ° C. for 24 hours to obtain layered double hydroxide particle powder as a catalyst precursor. The plate surface diameter of the layered double hydroxide particle powder was 0.298 μm, the crystallite size D006 was 0.041 μm, and the BET was 59.3 m ² / g.
Subsequently, this powdery catalyst precursor was formed into spherical beads having a diameter of 3 mm. Calcination was performed in air at 850 ° C. for 24 hours, and reduction treatment was performed at 850 ° C. in a gas stream having a hydrogen / argon volume ratio of 20/80 for 5 hours to obtain a hydrocarbon decomposition catalyst. The content of nickel in the obtained catalyst was 42.811 wt% (Ni / (total metal ions) = 0.360 (molar ratio)), and the size of the metal nickel fine particles was 35 nm. The ruthenium content in the obtained catalyst was 1.843 wt% (Ru / (total metal ions) = 0.0009 (molar ratio)), and the size of the metal ruthenium fine particles was 18 nm. In addition, it is estimated that metal nickel particle and metal ruthenium exist in the whole particle | grain.

<Comparative Example 1>
The α-alumina powder was fired in air at 1150 ° C. for 10 hours as 2.5 mm spherical beads. To this, 1000 ml of a solution in which 212.2 g of Ni (NO ₃ ) ₂ · 6H ₂ O was dissolved in pure water was applied by spraying, dried, and then fired in air at 660 ° C. for 6 hours. Further, reduction treatment was performed at 800 ° C. for 9 hours in a gas stream having a hydrogen / argon volume ratio of 20/80. The content of nickel in the obtained catalyst was 10.2 wt% (Ni / (total metal ions) = 0.09), and the size of the metal nickel fine particles was 48 nm.

<Comparative example 2>
The α-alumina powder was fired in air at 1200 ° C. for 5 hours as 2.5 mm spherical beads. To this, 1000 ml of a solution in which 212.2 g of RuCl ₃ was dissolved in pure water was applied by spraying, dried and baked in air at 580 ° C. for 5 hours. Further, reduction treatment was performed at 540 ° C. for 3 hours in a gas stream having a hydrogen / argon volume ratio of 20/80. The ruthenium content in the obtained catalyst was 9.015 wt% (Ru / total metal ions = 0.048), and the size of the metal ruthenium fine particles was 15 nm.

  As is apparent from Table 1, when the hydrocarbon cracking catalyst according to the present invention is used, the methane conversion is almost in the vicinity of chemical equilibrium at any temperature of 400 ° C to 1000 ° C.

  As is apparent from Table 2, when the hydrocarbon cracking catalyst according to the present invention is used, even when S / C is 1.5 and 3.0, the methane conversion is almost near the chemical equilibrium and high conversion. And maintains a high methane addition rate even in a long-time reaction.

  As is apparent from Table 3, when the hydrocarbon cracking catalyst according to the present invention is used, the methane conversion is as high as 84% or more, and the carbon deposition amount is 0.2% or less, which can suppress carbon deposition. It is.

  The catalyst for cracking hydrocarbons according to the present invention is excellent in catalytic activity even at low temperatures and has low steam because the catalytically active components of metallic nickel and metallic ruthenium are supported in a highly dispersed state in the form of fine particles that have not existed before. Is excellent in coking resistance and has excellent oxidation resistance.

Since the method for producing hydrogen according to the present invention uses the hydrocarbon decomposition catalyst, it is possible to produce hydrogen efficiently.

Claims (4)

One or more selected from magnesium, aluminum and nickel as constituent elements and selected from alkali metals (excluding Na), alkaline earth metals (excluding Mg), Zn, Co, Ce, Cr, Fe and La A hydrocarbon cracking catalyst containing an element, the hydrocarbon cracking catalyst comprising layered double hydroxide core particles composed of magnesium and aluminum, and a particle surface of the layered double hydroxide core particles Layered double water composed of one or more elements selected from magnesium, aluminum, nickel and alkali metals (excluding Na), alkaline earth metals (excluding Mg), Zn, Co, Ce, Cr, Fe, La The layered double hydroxide type particle powder in which the hydroxide layer is formed is heated and fired to obtain an oxide particle powder, and then the hydrocarbon content obtained by heating and reducing the oxide particle powder. A use catalyst, the average particle diameter of a 1~10nm the content of metallic nickel 0.1 to 40% and a content of the metal nickel hydrocarbons of the hydrocarbon cracking catalyst of metallic nickel particles A hydrocarbon cracking catalyst, which is 0.0007 to 0.342 relative to the total number of moles of all metal ions constituting the cracking catalyst.   The hydrocarbon cracking catalyst according to claim 1, further comprising ruthenium.   The hydrocarbon decomposition catalyst according to claim 1 or 2, wherein the catalyst is one or two selected from alkali metals (excluding Na), alkaline earth metals (excluding Mg), Zn, Co, Ce, Cr, Fe, and La. The hydrocarbon decomposition catalyst, wherein the content of the above elements is 0.1 to 10.0 in a molar ratio with respect to 1 mol of nickel and ruthenium constituting the hydrocarbon decomposition catalyst. A method for producing hydrogen by steam reforming a gas mainly comprising a lower hydrocarbon, comprising contacting the hydrocarbon cracking catalyst according to any one of claims 1 to 3, the lower hydrocarbon gas, and steam. To produce hydrogen.