JPH09262468A - Catalyst for producing high calorie gas and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst used to a process for producing an alternate natural gas high in calorie by subjecting hydrocarbon to steam reforming and to provide a production method of the catalyst. SOLUTION: The catalyst is obtained by depositing 1.5-4wt.% ruthenium on an activated alumina composite carrier obtained by burning at 450-600 deg.C a carrier base stock obtd. by compacting aluminum hydroxide, at least one kind carbonate selected form among group II, group III and lanthanoide metal in periodic table and oxy acid as a starting material, insolubilizing and fixing the ruthenium with an alkali aq. soln, and subjecting the material to reducing treatment at 80-500 deg.C, and the catalyst has >=60% ruthenium dispersibility. After the reducing treatment, a ruthenium retention rate on the catalyst is >=95%, and a specific surface area of the catalyst is preferably >=180m<2> /g, and before the reducing treatment, the material is preferably dried at <=100 deg.C under reduced pressure or normal pressure.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a catalyst used in a process for steam-reforming a hydrocarbon to produce a high-calorie alternative natural gas, and a method for producing the catalyst.

[0002]

BACKGROUND OF THE INVENTION The above alternative natural gas (subsitut)
e natural gas) is a high calorie fuel gas having a calorific value of about 40,000 kJ / m ³ in place of natural gas, and is generally abbreviated as SNG.

City gas in Japan is becoming high in calories (converting heat quantity), and the demand for SNG is increasing. Therefore, when light petroleum fractions such as naphtha and liquefied petroleum gas (LPG) are used as raw materials for city gas, it is necessary to gasify these to produce SNG.

[0004] In the SNG production plant from these light petroleum fractions, a steam reforming method using a nickel-based catalyst is often employed. In this plant, by appropriately adjusting the operating conditions, a gas having a low calorific value containing hydrogen as a main component, a gas having a relatively high calorific value containing methane and hydrogen as a main component, or an SNG consisting mostly of methane
Etc. can be manufactured.

[0005] As the nickel-based catalyst, a catalyst in which nickel is supported on a carrier such as alumina is widely used. However, the current nickel-based catalyst is liable to cause carbon deposition on the catalyst and the activity is apt to decrease. In order to prevent this, in an actual plant, usually, the ratio of the "molar number of steam" and the "molar number of carbon atoms in the raw hydrocarbon" at the time of the reforming reaction shown in Equation 1 (hereinafter referred to as S / C ratio) ) Is set high,
Carbon deposition is suppressed by the reaction shown in Chemical formula 1.

[0006]

[Equation 1]

[0007]

Embedded image

[0008] From the viewpoint of SNG production by steam reforming of hydrocarbons, it is necessary to increase the methane yield. At this time, the temperature of the steam reforming is 4 in consideration of thermodynamic equilibrium.
A low temperature region around 00 to 500 ° C. is preferable. This temperature range is as low as approximately の of the ordinary steam reforming reaction for the purpose of producing hydrogen, and is a temperature range in which the carbon deposition reaction is extremely likely to occur. Therefore, a catalyst having high activity and high selectivity is indispensable. Has become. From this viewpoint, attempts are also being actively made to suppress carbon deposition in nickel-based catalysts, and a method of adding an alkali metal or an alkaline earth metal to a catalyst system is known.

On the other hand, in order to reduce the cost and increase the methane yield, it is necessary to reduce the steam basic unit (the amount of steam used per unit of product), and it is strongly desired to operate at a low S / C ratio. It is rare. However, under such operating conditions at a low temperature and a low S / C ratio, a conventional nickel-based catalyst has a limit in its activity and life, and problems have arisen in practical use.

[0010] Recently, a ruthenium-based catalyst has attracted attention because it has an effect of suppressing carbon deposition and can be operated at a low S / C ratio (about 1/2 as compared with the case where a nickel-based catalyst is used). . As a ruthenium-based catalyst, a catalyst in which ruthenium is supported on an alumina or silica carrier (Japanese Unexamined Patent Publication No.
No. 4232), ruthenium supported on high-purity alumina (Japanese Patent Laid-Open No. 4-59048), and one using a carrier in which cerium oxide is added to an alkali metal oxide or an alkaline earth metal oxide (Japanese Patent Laid-Open No. H04-29048). 4-2651
56), using an alkali metal salt such as sodium ruthenate as a ruthenium precursor (JP-A-60-
227834), those using a stabilized or partially stabilized zirconia carrier (JP-A-2-286787), and the like.

However, the ruthenium-based catalyst is easily poisoned by a sulfur content such as hydrogen sulfide (Catalyst 35, 22).
(Page 4 (1993)), and it is known that when catalyst poisoning due to sulfur content occurs, carbon easily precipitates on the catalyst and the activity is reduced (International).
Gas Research Conference Proceedings, Vol. 4, p. 124 (1989)). That is, the ruthenium-based catalyst has the effect of suppressing carbon deposition,
If poisoning is caused by sulfur components such as hydrogen sulfide contained in the raw material, the advantages of the angle cannot be utilized, and this is a major obstacle to industrialization.

As described above, in the production of SNG by low-temperature steam reforming of hydrocarbons, it has been found that sufficient reaction activity and high selectivity can be obtained at a reaction temperature of about 400 to 500 ° C. Required. This temperature range corresponds to a range where carbon deposition is likely to occur and the catalyst activity is likely to decrease. In addition, impurities containing sulfur in the raw material,
With sulfur compounds such as odorants added to raw materials,
There is a high possibility that the catalyst will be poisoned, and further, carbon deposition due to sulfur poisoning may occur simultaneously.

[0013] In view of these points, the present inventors have first prepared an alumina carrier containing a rare earth metal or an alkaline earth metal as a third component (a component other than the active metal).
A catalyst in which ruthenium, an active metal component, is highly dispersed has been proposed (Japanese Patent Application No. 6-189404, Proceedings of the 25th Symposium on Petroleum and Petrochemicals (edited by the Japan Petroleum Institute), p. 366 (1).
995)).

By the way, the steam reforming catalyst in industrial SNG production is exposed to steam at a reaction temperature of 400 to 500 ° C. for a long time, and therefore, it is necessary to have sufficient mechanical strength. If only mechanical strength is required, compression molding or high temperature firing is sufficient, but with these methods,
There is a risk that the specific surface area will be significantly reduced and that the pores will be blocked. Therefore, from the viewpoint of industrial SNG production, improvement of mechanical strength without impairing specific surface area and pore volume, addition of a third component for imparting sulfur poisoning resistance and carbon deposition resistance, metal loading It is important to improve the dispersibility.

The improvement in the dispersibility of the supported metal can be easily achieved by reducing the amount of the supported metal. However, the reduction in the amount of the supported metal decreases the number of active points, and provides sufficient activity in the temperature range of 400 to 500 ° C. In addition to being unable to obtain, poisoning of some active sites tends to cause a decrease in the activity of the entire catalyst. For this reason, the SNG production catalyst is intended to improve the mechanical strength without impairing the specific surface area and pore volume of the catalyst carrier to which the third component is added, and to disperse a sufficient amount of the active metal. A precise design is required.

[0016]

The object of the present invention is to meet the above-mentioned requirements. It is excellent in mechanical strength, is resistant to sulfur poisoning and carbon deposition, has a low activity reduction over a long period of time, and has high efficiency and high efficiency. An object of the present invention is to provide a catalyst capable of producing a calorie gas and a method for producing the catalyst.

[0017]

SUMMARY OF THE INVENTION The present inventors have conducted extensive research in order to achieve the above object, and as a result, (1) a precursor of alumina,
A carrier substrate molded using a raw material containing aluminum hydroxide, at least one of carbonates of Group 2 and Group 3 and lanthanoid metals of the periodic table, and oxyacid is molded at a relatively low temperature ( The alumina composite carrier obtained by firing at 450 to 600 ° C. can efficiently support a considerable amount of ruthenium, and (2) this can be carried at a relatively low temperature (80 to 50).
When the catalyst reduced at 0 ° C.) is used for the steam reforming reaction of hydrocarbons in a low temperature region, it is possible to produce SNG stably for a long time while showing good reaction results close to the equilibrium conversion rate. ) It was found that the catalyst has practically sufficient strength even though it is calcined and reduced at a relatively low temperature.

The catalyst for producing a high-calorie gas of the present invention is based on the above-mentioned findings. (A) Aluminum hydroxide,
(B) at least one carbonate selected from the group consisting of Group 2 and Group 3 and lanthanoid metals of the periodic table,
(C) A carrier substrate molded from oxyacid as a raw material
To the activated alumina composite support obtained by firing at ~ 600 ° C,
Support ruthenium 1.5 to 4% by weight, 80 to 500 ℃
The ruthenium dispersibility is 60% or more.

In the above catalyst, the retention rate of ruthenium on the catalyst after the reduction treatment is 95% or more, and the specific surface area of the catalyst is 1
It is preferably 80 m ² / g or more.

The method for producing a catalyst for producing a high-calorie gas of the present invention has at least one selected from the group consisting of (a) aluminum hydroxide, (b) Group 2 and Group 3 of the Periodic Table and lanthanoid metals. 1.5 to 4% by weight of ruthenium is supported on an activated alumina composite carrier obtained by firing a carrier substrate formed by molding a carbonate of (c) oxyacid as a raw material at 450 to 600 ° C., and an alkaline aqueous solution. Is used to insolubilize and fix ruthenium, and then reduction treatment is performed at 80 to 500 ° C. so that the ruthenium dispersibility is 60% or more.

In the above-mentioned production method, it is preferable to dry at 100 ° C. or lower under reduced pressure or normal pressure prior to the reduction treatment at 80 to 500 ° C.

The catalyst of the present invention comprises (a) aluminum hydroxide (that is, an alumina precursor), (b) a carbonate of a metal of Group 2 (hereinafter referred to as Group 2) of the periodic table, and Group 3 of the periodic table ( Hereinafter, referred to as Group 3) at least one selected from the group consisting of metal carbonates and lanthanoid metal carbonates,
(C) A carrier raw material containing oxyacid is used.

As the aluminum hydroxide as the component (a) which is an alumina precursor, anhydrous aluminum hydroxide, hydrated aluminum hydroxide and the like can be used. The hydrate is used as it is or after dehydration in advance. From the viewpoint of handling convenience, the anhydride is preferable. The reason why aluminum hydroxide is used as an alumina precursor is that water (steam) is generated during the heating and firing steps, and the carrier is porous (porou).
s).

In the component (b), as the Group 2 metal carbonate,
Carbonates of beryllium, magnesium, calcium, strontium, barium and radium can be used, but carbonates of magnesium and barium are preferable. As the Group 3 metal carbonate, scandium or yttrium carbonate can be used, but yttrium carbonate is preferable. As the lanthanoid metal carbonate, carbonates such as lanthanum, cerium, praseodymium, neodymium, promethium and samarium can be used, but cerium and lanthanum carbonates are preferable.

These (b) component group 2, group 3 and lanthanoid carbonates may be used alone or in combination of two or more. However, there is little synergistic effect due to the combination, and the intended catalyst performance can be obtained by using one kind alone.

The reason why the carbonates of groups 2, 3 and lanthanoids are used as the starting material for the carrier is to obtain the effect of adding these metals, which will be described later, as well as to decarbonate during the heating and firing steps. This is to generate gas and make the carrier porous.

As the above components (a) and (b), chloride,
When nitrates, sulfates, etc. are used, these anions and anion atomic groups (sulfate ions, etc.) may remain in the catalyst as residues (eg, sulfate radicals, nitrate radicals), and these salts cannot be used. .

Examples of the oxyacid as the component (c) include glycolic acid, lactic acid, hydroacrylic acid, α-oxybutyric acid, glyceric acid, tartronic acid, malic acid, tartaric acid, citric acid, and other aliphatic oxyacids; salicylic acid, m -Aromatic oxyacids such as oxybenzoic acid, p-oxybenzoic acid, gallic acid, mandelic acid, and trovanic acid; those obtained by alkylating these aliphatic oxyacids and aromatic oxyacids (one of the carboxyl groups of oxyacids Various oxyacids such as those obtained by subjecting a part to alkylation such as methylation); These are 1
These can be used alone or in combination of two or more. When two or more kinds are mixed, an aliphatic oxyacid and an aromatic oxyacid may be used.

The reason for using an oxyacid or an alkylated product thereof (collectively referred to as oxyacid in the present invention) as the component (c) is to make the carrier porous.
These are mainly for decarboxylation due to thermal decomposition and for promoting the porosity of the carrier.

The component (c) is used in powder form (a),
(B) Mechanical mixing with the powder of the component (dry mixing)
Alternatively, the oxyacid may be dispersed in an organic solvent or a dispersion medium that does not dissociate, and this may be mixed with the powders of the components (a) and (b).

As the above organic solvent and dispersion medium, saturated
Low-polarity compounds such as unsaturated hydrocarbons, aromatic compounds, and alicyclic organic compounds are preferred. Those that do not leave residues during heating and firing and those that do not generate corrosive or harmful gases should be selected. .

The reason for using a non-polar solvent or a dispersion medium when adding the component (c) is to suppress dissociation of Group 2 and Group 3 and lanthanoid carbonates. When these dissociate,
This is because it decomposes by reacting with oxyacid or aluminum hydroxide.

The support is made porous by dehydration of aluminum hydroxide, decarboxylation of group 2, group 3 or lanthanoid carbonate, or decarboxylation of oxyacid. Therefore, the reaction of the raw materials with each other before heating and firing means that there is no contribution to the effect of improving the catalyst performance.

The compounding amounts of the respective components in the carrier raw material comprising the components (a) to (c) are as follows.

The group 2 metal carbonate, the group 3 metal carbonate, and the lanthanoid metal carbonate as the component (b) are 5 to 20% by weight, preferably 5 to 20% by weight, based on the catalyst, as oxides of these metals after firing of the carrier substrate. Is 7-18% by weight, more preferably 7.5
To 12% by weight.

When the content of the component (b) is less than 5% by weight, it is difficult to obtain a sufficient effect on the sulfur resistance, and therefore sulfur poisoning and carbon precipitation are accompanied, so that the catalyst performance can be kept stable for a long period of time. I can't. If the content as an oxide is appropriate, the sulfur compound contained in the raw material is Group 2, Group 3,
Since it is adsorbed and absorbed by the lanthanoid oxide, ruthenium, which is the active ingredient, is less likely to be poisoned and the life is extended. When the amount of the component (b) exceeds 20% by weight, the content of alumina due to the component (a) is relatively decreased. Alumina contributes to the improvement of the mechanical strength and specific surface area of the catalyst. If the content is extremely reduced, not only is it not possible to obtain practical strength but also it is difficult to highly disperse the active ingredient.

The component (c) is 1 to 70% by weight, preferably 3 to 50% by weight, more preferably 7 to 35% by weight, based on the weight of the activated alumina composite support after firing of the support base material.
It is. If it is less than 1% by weight, the carrier does not become sufficiently porous, and the required amount of ruthenium cannot be supported.
It also reduces dispersibility. If it exceeds 70% by weight, the porosity is improved, but there are more factors that impair the catalyst performance, such as the formation of macropores and carbon residue due to incomplete combustion.

The order of mixing the components (a) to (c) when preparing the carrier is not particularly limited, and the components (a) and (b) are thoroughly mixed and the component (c) is added thereto. Good
The components (a) and (c) may be sufficiently mixed and the component (b) may be added thereto, or the components (a) to (c) may be simultaneously added and mixed.

It should be noted that addition of other components such as other metal oxides to the above-mentioned carrier raw material is not hindered as long as the effects of the present invention are not impaired.

The above carrier raw material is molded into a carrier substrate,
Although it is calcined to obtain an activated alumina composite carrier, when the carrier raw material contains a solvent and a dispersion medium, it is preferable to completely remove these in advance when molding the carrier substrate. For removal, drying may be performed at normal pressure or reduced pressure, at normal temperature or under heating. When heating and drying, the temperature is preferably 100 ° C. or lower from the viewpoint of not changing the properties of the carrier raw material.

Prior to molding, the carrier raw materials are preferably uniformly mixed to obtain fine powder. The powder is 50 mesh, preferably 100 mesh, more preferably 20 mesh.
Those that pass through a 0 mesh sieve are suitable.

As the molding, various methods such as pressure molding and extrusion molding can be applied, but pressure molding is preferable. Examples of pressure molding include tablet molding, injection molding, press molding and the like, but tablet molding is preferable in view of reaction conditions. The shape to be molded is spherical, elliptical spherical, spindle-shaped, prismatic, cylindrical, hollow, tablet-shaped, and other various granular materials, and may be a film or other various shapes, and is not particularly limited. However, it is preferable to use a columnar, hollow, or tablet-like granular material used in a general steam reforming reaction.

The molded carrier substrate is fired in air to form an activated alumina composite carrier. The firing temperature is 650 ° C or lower, preferably 450 to 600 ° C, and the firing time is 1 to 20.
Time is suitable.

The activated alumina composite support thus obtained preferably has a specific surface area of 190 m ² / g or more and a pore volume of 0.2 to 0.4 ml / g. If the specific surface area or pore volume of the carrier is less than these values, it becomes impossible to carry the required amount of ruthenium and the dispersibility of ruthenium also decreases.

In order to support ruthenium on the activated alumina composite carrier, the following method is preferable. First, prior to supporting ruthenium, the saturated water absorption of the carrier is determined. That is, the carrier is weighed in advance, and water is appropriately added to the carrier by a buret to absorb the water sufficiently to the inside of the carrier, and the saturated water absorption is measured. Then, an aqueous solution in which a predetermined amount of ruthenium trichloride hydrate is dissolved in ion exchange water or distilled water in an amount equal to the saturated water absorption amount is absorbed by the carrier.

After that, 10 to 15% by volume of ammonia water is appropriately adjusted to an excessive amount with respect to the ruthenium concentration to convert ruthenium chloride into hydroxide as shown in Chemical formula 2, and ruthenium is insoluble and fixed on the carrier. Turn into This method also has an advantage that dechlorination can be efficiently performed during the washing process because the chloride anion is converted into water-soluble ammonium chloride.

[0047]

Embedded image RuCl ₃ + 3NH ₄ OH → Ru (OH) ₃ +
3NH ₄ Cl

The temperature of the above-mentioned aqueous solution of ruthenium chloride hydrate is lower than 50 ° C., preferably room temperature, in order to avoid hydrolysis of ruthenium chloride.

The ruthenium source is not limited to the above-mentioned ruthenium trichloride hydrate, but ruthenium trichloride anhydride, ruthenates such as potassium ruthenate, and ruthenium compounds such as ruthenium nitrate can also be used. Further, ruthenium can be insoluble and fixed by using an aqueous alkali solution such as sodium carbonate (soda ash), sodium hydrogen carbonate (sodium bicarbonate), sodium hydroxide and potassium hydroxide, in addition to ammonia water. However, when using these alkali salts, ammonia water is the easiest to handle because there is a concern that alkali cations remain during washing.

The amount of ruthenium supported is 1.5 to 4% by weight, preferably 2 to 4% by weight, based on the catalyst after the reduction treatment.
More preferably, it is 2.3 to 3% by weight. To improve only the dispersibility of the active metal, the amount of the supported metal may be reduced as described above. However, the catalyst used in the low-temperature steam reforming reaction of hydrocarbons for the purpose of producing SNG of the present invention is not suitable. Therefore, it is important to have a desired level of active sites and dispersibility. When the supported amount of ruthenium is less than 1.5% by weight, the dispersibility is at a desired level, but the amount of active sites is not at a desired level. Even if the initial activity is sufficient, the S / C ratio fluctuates during operation. , GHSV, operating temperature, etc., a small change or change in operating conditions may cause a decrease in activity. On the other hand, if it exceeds 4% by weight, the interval between the active metal fine particles is narrowed, so that sintering or the like may occur.

Since activated alumina and activated alumina composite support, which have been widely used as catalyst supports, have a small specific surface area and a low porosity, a large amount of ruthenium as described above can be added to these supports at once. It could not be supported. Therefore, conventionally, a multi-step impregnation method such as a two-step impregnation method or a three-step impregnation method, or an impregnation method using a high-concentration ruthenium chloride aqueous solution has been required. However,
Also by these methods, there is a concern that ruthenium evaporates to dryness on the catalyst at a high rate and impairs catalyst performance.

On the other hand, in the activated alumina composite carrier of the present invention, the amount of ruthenium in the aqueous solution in which the ruthenium compound used in the above impregnation is dissolved (charged amount,
95% or more of the number of moles) can be supported by single-step impregnation, and a predetermined amount of ruthenium can be supported with a high dispersibility of 60% or more.

As described above, in the present invention, after the ruthenium solution is impregnated, the insoluble / immobilizing operation is performed with an aqueous alkaline solution such as ammonia water. There is no formation of a complex of ruthenium species and alkali species (for example, ammine complex <reddish color>) that is not supported on the carrier. Therefore, in the activated alumina composite carrier of the present invention, ruthenium is efficiently supported. I understand that.

The carrier in which ruthenium is insoluble / immobilized is desirably dried at 100 ° C. or lower, preferably 90 ° C. or lower, more preferably 50 ° C. or lower under reduced pressure or normal pressure prior to the reduction treatment. This is to suppress oxidation of ruthenium hydroxide on the catalyst surface. If an oxide is present during the reduction treatment, it is expected that the degree of reduction will be non-uniform, and that the oxide is difficult to be reduced and will remain as an oxide on the catalyst surface. Residue may impair the dispersibility of ruthenium. Therefore, it is preferable that the reduction treatment is not performed immediately after insolubilization / immobilization, but the drying is performed in the low temperature region as described above.

Further, when drying, it is extremely reasonable to use a rare gas such as helium or argon, or an inert gas stream such as nitrogen, but if the operation is carried out at 100 ° C. or lower as described above, air will flow. Even in the middle, the amount of oxides produced is very small and does not pose a problem. In the operation in air, the lower the drying temperature is, the more advantageous it is in suppressing the oxide formation. However, when the drying temperature is too low, the drying time becomes extremely long, which is not practical. The drying time may be appropriately selected according to the conditions such as the drying temperature and the amount of the object to be dried, but is usually preferably about 1 to 20 hours.

When the ruthenium-supported catalyst thus obtained is subjected to a reduction treatment at a relatively low temperature, the ruthenium uniformly supported by impregnation (that is, in a highly dispersed state) remains as it is (that is, in a highly dispersed state). ) Can be kept. The reduction temperature is 80 to 500 ° C, preferably 100 to 480 ° C, more preferably 120 to 45 ° C.
0 ° C. When reduced in such a relatively low temperature range, the high dispersibility of ruthenium can be stably maintained.

Ruthenium before the reduction treatment exists as a hydroxide, and the ruthenium hydroxide is 60 to 80 ° C.
Ru ⁰ (metallic stat) in a temperature range of about
e) is reduced. Therefore, the ordinary steam reforming catalyst requires reduction at a high temperature of about 700 ° C., whereas the catalyst of the present invention has such a feature that it can be reduced at an extremely low temperature of 60 to 80 ° C. , Supported metal (Ru)
Can maintain high dispersibility.

The decrease in dispersibility is generally caused by sintering (sintering). Sintering can have at least two causes. One is the sintering of the carrier itself. Even if the active metal is highly dispersed, the sintering of the carrier by the heat history narrows the particle spacing of the active metal and lowers the dispersibility. The other is due to sintering of the active metal itself.

In the catalyst of the present invention, the temperature of calcination of the carrier is set to the steam reforming temperature or higher, and ruthenium (melting point of metal Ru is 2450 ° C.) having a high melting point is selected as the active metal, whereby the steam reforming reaction is performed. It makes the carrier and active metal in (3) difficult to receive the thermal history.

In the present invention, the reduction of the catalyst can theoretically be carried out at the extremely low temperature of 60 to 80 ° C. mentioned above, but in the case of an extremely finely divided active metal, only a part thereof can be obtained. Since it is possible that the active points of
The above temperature range (80 to 500 ° C.) is set so that stable catalytic performance can be obtained for a long period in an actual plant.

As the reducing gas, hydrogen gas, hydrogen / steam mixed gas, carbon monoxide and the like can be used. Among them, hydrogen gas or hydrogen / steam mixed gas is preferable, and hydrogen gas is particularly preferable. The reduction time may be appropriately selected according to the conditions such as the reduction temperature and the gas flow rate of the reducing gas,
About 1 to 20 hours is practical.

The catalyst of the present invention obtained as described above has a ruthenium retention of 95% or more and a specific surface area of 180.
m ² / g or more, carbon monoxide (hereinafter sometimes referred to as CO) adsorption amount of 2.5 ml / g or more, and ruthenium metal dispersibility of 60% or more, which are extremely excellent values. This means that ruthenium metal active sites are sufficiently present on the catalyst surface, and that the composite carrier is sufficiently exposed on the catalyst surface (that is, in the catalyst in which fine particle ruthenium is supported in a highly dispersed state, The influence of ruthenium particles on the surface exposure of the carrier is small, and the carrier is sufficiently exposed on the catalyst surface, whereas the catalyst in which ruthenium fine particles are laminated or agglomerated by sintering etc. The surface exposure of the carrier is reduced by the amount covered with ruthenium. Therefore, the sulfur content contained in the steam reforming raw material is effectively adsorbed and absorbed on the carrier side. Even if some ruthenium is poisoned, or if the load on the catalyst is changed due to changes in operating conditions,
Due to the large number of active sites, the catalytic performance is stably maintained for a long time.

The ruthenium dispersibility in the present invention is the percentage of the number of moles of adsorbed CO of the product catalyst (catalyst after the reduction treatment) with respect to the number of moles of ruthenium, and is represented by the formula (2).
Further, the ruthenium retention is a percentage of the number of moles of ruthenium contained in the aqueous ruthenium solution used in the impregnation of the ruthenium moles contained in the product catalyst obtained by the ICP analysis, and is expressed by the following equation. The higher the value is, the more efficiently it is carried.

[0064]

[Equation 2]

That is, the ruthenium dispersibility (%) is C
O selectively chemisorbs to metal Ru (Ru ⁰ ) (chem
The percentage of the active sites (Ru) that can participate in the actual catalytic reaction among the ruthenium contained in the catalyst is shown in percentage by utilizing the property of isortion. Therefore, if there is ruthenium hidden from the surface due to sintering or evaporation to dryness, or ruthenium that cannot be exposed to the surface due to condensation of a metal or the like, adsorption of CO does not occur and the value of dispersibility decreases.

In the catalyst of the present invention, out of 1.5 to 4% by weight of ruthenium, 60% or more is an active site capable of contributing to the reaction. This indicates that many active sites exist on the catalyst surface and that the activated alumina composite carrier is also sufficiently exposed on the catalyst surface. Therefore, according to the catalyst of the present invention, the low-temperature steam reforming reaction of hydrocarbons for the purpose of producing SNG can be stably continued for a long time under the condition of a low S / C ratio. Further, even if the raw material contains sulfur, or the S / C ratio or the supply amount of the raw material fluctuates, if the dispersibility of ruthenium is 60% or more, there are many active sites, so that these are hardly affected. In addition, the catalyst performance is hardly impaired.

On the contrary, if the ruthenium dispersibility is less than 60%, the apparent reaction rate is lowered because the number of active sites is small. Further, the active alumina composite carrier is less likely to be exposed on the surface of the catalyst, so that the carrier effect is reduced. Furthermore, since the number of active points is small, there is a concern that the catalytic performance may be deteriorated due to a change in the sulfur content in the raw material, operating conditions, and the like.

The above-described catalyst of the present invention has sufficient mechanical strength, is excellent in sulfur poisoning resistance, and exhibits good reaction results close to equilibrium conversion. Therefore, the catalyst of the present invention exhibits good steam reforming activity even with a raw material containing a sulfur compound.

The hydrocarbon as the main component of the raw material when producing a high-calorie gas by the catalyst of the present invention has 2 to 16 carbon atoms, preferably 2 to 10 carbon atoms, more preferably 3 to 10 carbon atoms.
8 is preferably used. The reaction temperature is 350 to 500 ° C, preferably 400 to 450 ° C, and the reaction pressure is 20 kg / cm.
² G or less, preferably normal pressure to 15 kg / cm ² G, more preferably 8 to 10 kg / cm ² G, GHSV is 600
It is preferably set to 1200 (v / v) h ⁻¹ . The amount of steam added to the reaction system is preferably 0.7 to 10 in terms of S / C ratio. The reaction system is preferably a batch system, a semi-continuous system, or a continuous system using a fixed-bed or moving-bed reactor.

[0070]

EXAMPLES In the following examples, the products were analyzed using stainless steel (SUS) tubes (inner diameter 3 mmφ × 2 m).
0-80 mesh filler (Unibeads-C, G
It was carried out by a gas chromatograph (GC-9A, manufactured by Shimadzu Corporation) equipped with a thermal conductivity detector (TCD) equipped with a separation column filled with L Science (trade name) manufactured by L Science Co., Ltd. The specific surface area and pore volume of the support and the catalyst were determined by a surface area measuring device (Bellsoap 28, trade name of Bell Japan Co.), and the amount of CO adsorbed was measured by an automatic gas adsorption device (R6015, manufactured by Okura Riken Co., Ltd. with a TCD gas chromatograph) Name). Catalyst breaking strength (DWL: d
The head weight was measured by a Kiya type hardness tester (manufactured by Kiya Seisakusho). The amount of ruthenium supported on the catalyst was confirmed by inductively coupled plasma emission analysis (ICP analysis).

[0071] Example 1 of cerium carbonate octahydrate _{(Ce 2 (CO 3) 3} · 8H
₂ O, manufactured by Kanto Chemical Co., Ltd.) powder 6.6 g, anhydrous aluminum hydroxide (Al (OH) ₃ , manufactured by Kanto Chemical Co., Ltd.) powder 69.6
g, and 17.5 g of tartaric acid (C ₄ H ₆ O ₆ ) powder,
Mix thoroughly in an agate mortar. This powder (200 mesh) was molded into a columnar shape (pellets) with a tablet molding machine, and was fired in a muffle furnace in air at 500 ° C. for 3 hours to obtain carrier pellets. The gas generated during the generation was exhausted into the draft chamber using a water pump provided with an exhaust pipe in the muffle furnace. The specific surface area of the composite carrier thus obtained was 230 m ² / g, and the pore volume was 0.35.
ml / g.

3 g of ruthenium trichloride monohydrate (manufactured by Mitsuwa Chemical Co., Ltd., ruthenium content: 44 to 45 wt%) was dissolved in water to make 100 ml, and 22.1 g of the above carrier pellets was added to 25 ml of this aqueous solution at room temperature for 1 hour. Soaked. Pellets taken out of the aqueous solution are removed by residual liquid, and then about 2.7 kPa (about 20 mmHg) by a rotary evaporator.
The water was removed while heating to about 40 ° C. with an infrared hot plate under a degree of vacuum. This pellet is mixed with about 1 liter of 7 to 10N aqueous ammonia (about 2 liters of a special grade of commercial reagent).
(Double dilution), and the mixture was slowly stirred with a stirrer for 2 hours while maintaining the temperature at 30 ° C. to insoluble and fix ruthenium. The pellet was recovered from aqueous ammonia using a Buchner funnel.

The recovered pellets were thoroughly washed with pure water (ion exchanged water). The washing was carried out by dropping a dilute silver nitrate aqueous solution on a part of the filtrate until the cloudiness of silver chloride did not occur. The washed pellets were dried in a vacuum oven at 40-45 ° C for 8-10 hours. 10 ml of dried pellets
Packed in a normal pressure flow reactor, pressure 0.78MP
a (8 kg / cm ² G), reduction temperature 450 ° C., GHSV
It was reduced at 900 (v / v) h ⁻¹ for 8 hours with hydrogen whose flow rate was adjusted by a mass flow controller to obtain a catalyst A.

The catalyst A is composed of ruthenium (1.5 wt%), cerium oxide (7.5 wt%) and the remaining alumina, and has a specific surface area of 225 m ² / g and a breaking strength (DWL) of 24.0 k.
g. The CO adsorption amount was 2.7 ml / g (STP: standard state converted value). Since CO adsorption is not observed only on the alumina carrier which does not support ruthenium, it can be said that this value indicates the adsorption amount on ruthenium. The ruthenium dispersibility was calculated by using the formula 2 and was 8
It was 0%. The number of moles of ruthenium in the ruthenium trichloride solution (hereinafter referred to as the charge liquid) used for supporting ruthenium (3.35 × 10 ⁻³ ), and the amount of ruthenium supported on the post-reduction catalyst obtained from ICP analysis results. Number (3.
From 32 × 10 ⁻³ ), it can be seen that 99% (retention rate) of ruthenium contained in the charged solution was supported on the catalyst. The properties of Catalyst A are summarized in Table 1.

Next, the reactor filled with catalyst A was charged with commercially available L
PG gas (Cosmo Oil Corporation, trade name, Cosmo butane Silver _{C 3: 3vol%, iso-} C 4: 32vol%, n
-C _4: to 65 vol%) those of hydrogen sulfide were added 10 ppm, is introduced together with steam, was produced SNG performs steam reforming reaction of the LPG gas. The reaction conditions are a pressure of 8 kg / cm ² G (0.78 MPa) and a reaction temperature of 45.
It carried out at 0 degreeC, GHSV600 (v / v) h- ¹ , and S / C ratio 1. The reaction results are shown in Table 2.

Example 2 Example 2 except that 6.6 g of cerium carbonate octahydrate powder, 69.0 g of aluminum hydroxide anhydrous powder and 14.8 g of tartaric acid (same as used in Example 1) powder were used. A composite carrier (pellet) was prepared in the same manner as in Example 1. The specific surface area of the obtained composite carrier is 236 m ² / g,
The pore volume was 0.40 ml / g.

22 g of the above carrier pellets were mixed with ruthenium trichloride monohydrate (the same as that used in Example 1).
A catalyst B was prepared in the same manner as in Example 1 except that 25 ml of water containing 15 g was immersed. Catalyst B consists of 2.3 wt% ruthenium, 7.5 wt% cerium oxide, and the balance alumina, and has a breaking strength of 23.7 kg and a specific surface area of 225 m.
² / g, ruthenium retention rate 99.0%, CO adsorption amount 4.
1 ml / g (STP), ruthenium dispersibility was 80%. The properties of catalyst B are summarized in Table 1, and the results of the steam reforming reaction similar to that of Example 1 performed using catalyst B are shown in Table 2.
It was shown to.

Example 3 Yttrium carbonate (Y ₂ (CO ₃ ) ₃ , manufactured by Wako Pure Chemical Industries, Ltd.) powder 4.4 g, aluminum hydroxide anhydride (same as used in Example 1) powder 70.4 g, and tartaric acid 0.5 g of powder (same as used in Example 1) was thoroughly mixed in an agate mortar. Carrier (pellet) in the same manner as in Example 1 except that this powder (100 mesh) was used.
Was prepared. The specific surface area of the obtained composite carrier is 225 m
² / g, and the pore volume was 0.33 ml / g.

Catalyst C was prepared in the same manner as in Example 2 except that 22.2 g of the above carrier pellets were used. Catalyst C is ruthenium 2.3 wt%, yttrium oxide 5w
t%, the rest consisting of alumina, breaking strength 24.5 kg,
Specific surface area 216 m ² / g, ruthenium retention rate 99.1
%, CO adsorption amount 4.0 ml / g (STP), and ruthenium dispersibility 78%. The properties of Catalyst C are summarized in Table 1, and the results of the same steam reforming reaction as in Example 1 performed using Catalyst C are shown in Table 2.

Example 4 8.4 g of lanthanum carbonate (La ₂ (CO ₃ ) ₃ , manufactured by Wako Pure Chemical Industries, Ltd.) powder, 65.0 g of anhydrous aluminum hydroxide (the same as that used in Example 1) powder, and tartaric acid 3.5 g of powder (same as that used in Example 1) was thoroughly mixed in an agate mortar. A carrier (pellet) was prepared in the same manner as in Example 1 except that this powder (50 mesh) was used. The specific surface area of the obtained composite carrier is 221 m ² /
g, the pore volume was 0.38 ml / g.

To 22.2 g of this carrier, 1.56 g of ruthenium trichloride monohydrate (same as used in Example 1)
A catalyst D was prepared in the same manner as in Example 1 except that 25 ml of water containing Catalyst D is ruthenium 3 wt
%, Lanthanum oxide 12% by weight, and the balance alumina.
Breaking strength 23.1 kg, specific surface area 210 m2 / g, ruthenium retention 96.7%, CO adsorption 4.7 ml / g
(STP), ruthenium dispersibility was 70%. Catalyst D
The properties of the above are collectively shown in Table 1, and the results of the steam reforming reaction similar to that of Example 1 performed using the catalyst D are shown in Table 2.

Example 5 Magnesium carbonate (MgCO ₃ , manufactured by Wako Pure Chemical Industries, Ltd.) powder 1
2.5 g, anhydrous aluminum hydroxide (the same as that used in Example 1) powder 64.3 g, and tartaric acid (the same as that used in Example 1) powder 24.8 g were thoroughly mixed in an agate mortar. did. Carrier (pellet) in the same manner as in Example 1 except that this powder (100 mesh) was used.
Was prepared. The specific surface area of the obtained composite carrier is 205 m
² / g, and the pore volume was 0.37 ml / g.

A catalyst E was prepared in the same manner as in Example 1 except that 25 g of water containing 2.10 g of ruthenium trichloride monohydrate (the same as that used in Example 1) was immersed in 22 g of this carrier. did. The catalyst E was composed of 4 wt% of ruthenium, 12 wt% of magnesium oxide, and the remaining alumina, and had a breaking strength of 23.7 kg, a specific surface area of 185 m ² / g, a ruthenium retention rate of 95.2%, and a CO adsorption amount of 5.4 ml / g (S
TP), and ruthenium dispersibility was 61%. The properties of catalyst E are summarized in Table 1, and the results of the steam reforming reaction similar to that of Example 1 performed using catalyst E are shown in Table 2.

Example 6 Barium carbonate (BaCO ₃ , manufactured by Wako Pure Chemical Industries) powder 12.9
g, aluminum hydroxide anhydrous (the same as that used in Example 1) powder 58.1 g, and tartaric acid (the same as that used in Example 1) powder 35.1 g were thoroughly mixed in an agate mortar. A carrier (pellet) was prepared in the same manner as in Example 1 except that this powder (200 mesh) was used. The specific surface area of the obtained composite carrier was 193 m ² /
g, the pore volume was 0.31 ml / g.

A catalyst F was prepared in the same manner as in Example 5 except that 22.1 g of this carrier was used. The catalyst F is composed of 4 wt% of ruthenium, 20 wt% of barium oxide and the rest of alumina, and has a breaking strength of 24.5 kg and a specific surface area of 181 m _2.
/ G, ruthenium retention rate 95.1%, CO adsorption amount 5.3
ml / g (STP), ruthenium dispersibility was 60%. The properties of the catalyst F are summarized in Table 1, and the results of the steam reforming reaction similar to that of Example 1 performed using the catalyst F are shown in Table 2.
It was shown to.

Example 7 A composite carrier was obtained in the same manner as in Example 2. The specific surface area of this composite carrier is 230 m ² / g, and the pore volume is 0.35 ml.
/ G. A catalyst G was prepared in the same manner as in Example 2 except that the reduction temperature was 80 ° C. The catalyst G is composed of 2.3 wt% ruthenium, 7.5 wt% cerium oxide and the rest alumina, and has a breaking strength of 23.6 kg and a specific surface area of 226.
m ₂ / g, ruthenium retention rate 99%, CO adsorption amount 4.1
ml / g (STP), ruthenium dispersibility was 80%. The properties of catalyst G are summarized in Table 1, and the results of the steam reforming reaction similar to that of Example 1 performed using catalyst G are shown in Table 2.
It was shown to.

Comparative Example 1 Alumina (Al ₂ O ₃ , aluminum oxide 90, T
3.2, powder 48.5 g)
It was tabletted into mmφ pellets and fired in the same manner as in Example 1 to give a specific surface area of 110 m ² / g and a pore volume of 0.18 ml.
/ G of alumina carrier was obtained. 25 ml of water containing 1.75 g of ruthenium trichloride monohydrate (the same as that used in Example 1) was immersed in 22.3 g of this carrier, and after removing the residual liquid, it was washed with pure water and at 110 ° C. After drying for 5 hours, catalyst H
Was prepared. The catalyst H was ruthenium 2.3 wt. %, Consisting of remaining alumina, fracture strength 23.7 kg, specific surface area 52 m ² / g, ruthenium retention rate 75.4%, CO adsorption amount 1.9 ml / g (STP), ruthenium dispersibility 38%
Met. The properties of the catalyst H are shown in Table 1 collectively.
Table 2 shows the results of the steam reforming reaction similar to that of Example 1 performed using

The conversion rate and selectivity shown in Table 2 are obtained by
Calculated from the formula shown in

[0089]

(Equation 3)

[0090]

[Table 1-1]

[0091]

[Table 1-2]

[0092]

[1 of Table 2]

[0093]

[Table 2-2]

As is clear from Table 2, the conversion rate is low in Comparative Example 1 using the conventional catalyst. This is because the specific surface area of the carrier was reduced and pores were clogged and the desired amount of ruthenium could not be carried in a highly dispersed state during the tableting step or firing step during catalyst preparation.

As is clear from Table 1, Examples 1 to 6
Has a ruthenium dispersibility that is about twice as high as that of Comparative Example 1. Further, the ruthenium retention rate in each of Examples 1 to 6 is improved by 30% as compared with Comparative Example 1. From these, in conventional catalysts, ruthenium and ruthenium oxide, which are difficult to reduce, exist on the surface of the catalyst in a dry state.As a result, the distance between ruthenium is close and ruthenium oxide or ruthenium chloride that does not show catalytic activity is present. Is believed to exist.

As described above, the conventional catalyst has few active points on the catalyst surface, and the carrier component is not sufficiently exposed on the catalyst surface, so that the carrier effect is small. Therefore, poisoning due to sulfur content easily occurs, carbon deposition due to sulfur poisoning proceeds,
This means that the selectivity of Comparative Example 1 is low.

On the other hand, in the catalyst of the present invention, since the specific surface area is wide and ruthenium is highly dispersed and supported on the carrier, the number of active sites is large, the carrier effect is sufficiently exhibited, and the catalyst performance is stable. It is clear. Moreover, in the catalyst of the present invention, since the ruthenium complex (ammine complex) due to the unsupported ruthenium content is not found in the filtrate,
It is clear that the ruthenium retention rate is high, and it is also clear that the starting material can be supported as an active site without waste. Therefore, when the catalyst of the present invention is used, it is possible to sufficiently cope with fluctuations in operating conditions and the like, and it is possible to stably produce SNG for a long time.

[0098]

EFFECTS OF THE INVENTION According to the present invention, it is possible to provide a catalyst having a practical level of strength and having both sulfur resistance and carbon precipitation resistance.
In the industrial process for producing G, excellent reaction results with high selectivity and high conversion can be maintained for a long period of time.

Front Page Continuation (72) Inventor Takashi Yoshizawa 1134-2 Gongendo, Satte City, Saitama Cosmo Research Institute Co., Ltd.

Claims (5)

[Claims] 1. Molded from (a) aluminum hydroxide, (b) at least one carbonate selected from the group consisting of groups 2 and 3 of the periodic table and lanthanoid metals, and (c) oxyacid as a raw material. The activated alumina composite carrier obtained by firing the carrier substrate at 450 to 600 ° C. carries 1.5 to 4% by weight of ruthenium and is subjected to a reduction treatment at 80 to 500 ° C., and has a ruthenium dispersibility of 60%. The above is a catalyst for producing high-calorie gas. 2. The catalyst for producing high-calorie gas according to claim 1, wherein the retention rate of ruthenium on the catalyst after the reduction treatment is 95% or more. 3. The specific surface area of the catalyst after the reduction treatment is 180 m
^The catalyst for producing a high-calorie gas according to claim 1, which has a content of ² / g or more. 4. A carrier formed by using (a) aluminum hydroxide, (b) at least one carbonate selected from the group consisting of Groups 2 and 3 of the Periodic Table and lanthanoid metals, and (c) an oxyacid as a raw material. Ruthenium is added to the activated alumina composite support obtained by firing the base material at 450 to 600 ° C.
Of 4 to 4% by weight, ruthenium is insoluble and fixed in an alkaline aqueous solution, and then reduction treatment is carried out at 80 to 500 ° C., so that the ruthenium dispersibility is 60% or more. Manufacturing method. 5. The method for producing a catalyst for producing a high-calorie gas according to claim 4, wherein the reduction treatment is dried at 100 ° C. or lower under reduced pressure or normal pressure.