JPH1024235A - Catalyst for producing high calorie gas and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst used for a process for producing a high calorie substitutive natural gas by steam-reforming a hydrocarbon of the like. SOLUTION: The catalyst is produced by carrying 1.5-4wt.% ruthenium on an active alumina composite carrier and reducing at 80-800 deg.C. The active alumina composite carrier is obtained by firing at 500-6500 deg.C a carrier base material formed by molding a raw material containing (a) aluminum oxide, (b) at least one kind selected from a group composed of oxide or group II, group III and lanthanoid metals in periodic table and (c) an oxyacid. The catalyst is preferably >=60% in ruthenium dispensability (= (the mole of adsorbed CO on the catalyst)/(the mole of ruthenium in the catalyst)×100) and >=2.0ml/g in carbon monoxide adsorption at 50 deg.C in normal condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a catalyst used in a process for producing a high calorie alternative natural gas by steam reforming a hydrocarbon or the like, 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.

[0003] The supply of city gas in Japan is toward higher calorie (calorific value conversion), and the demand for SNG is increasing. Therefore, when using light petroleum fractions such as naphtha and liquefied petroleum gas (LPG) as city gas feedstock,
These need to be gasified 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 (JP-A-4-59048), and a carrier obtained by adding cerium oxide to an alkali metal oxide or an alkaline earth metal oxide (JP-A-Hei 4-59048). 4-2651
No. 56), using an alkali metal salt such as sodium ruthenate as a ruthenium precursor (JP-A-60-1985)
227834) and those supported on a stabilized or partially stabilized zirconia carrier (JP-A-2-286787).

However, ruthenium-based catalysts are easily poisoned by sulfur such as hydrogen sulfide (catalysts 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 region corresponds to a region where carbon deposition is liable to occur and the activity of the catalyst is likely to decrease. In addition, there is a high possibility that the catalyst is poisoned by impurities containing sulfur components in the raw material and sulfur compounds such as odorants added to the raw material, and at the same time, coexistence of carbon deposition caused by sulfur poisoning. Is concerned.

[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, since the steam reforming catalyst in the industrial SNG production is exposed to steam for a long time at a reaction temperature of 400 to 500 ° C., it is necessary to have sufficient mechanical strength. In terms of mechanical strength alone, compression molding or high-temperature sintering is sufficient. However, these methods may cause a significant decrease in specific surface area or blockage of pores. 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 requirements.
An object of the present invention is to provide a catalyst which is excellent in mechanical strength, is excellent in sulfur poisoning resistance and carbon deposition resistance, has a small activity reduction for a long time, and is capable of efficiently producing a high calorie gas, and a method for producing the same. Aim.

[0017]

SUMMARY OF THE INVENTION To achieve the above object, the present inventors have first selected from the group consisting of (a) aluminum hydroxide and (b) Group 2 and 3 of the periodic table and lanthanoid metals. A catalyst in which ruthenium is supported on an activated alumina composite carrier obtained by calcining a carrier substrate obtained by molding a raw material containing at least one kind of carbonate and (c) oxyacid, and then subjected to a reduction treatment. (See Japanese Patent Application No. 8-99266).

However, in the catalyst proposed earlier,
The aluminum hydroxide of the component (a) and the carbonate of the component (b) are relatively expensive, and it is necessary to avoid water during the production of the catalyst. That is, if a large amount of water is present during the production of the catalyst, there is a high possibility that the carbonate of the component (b) and the oxyacid of the component (c) will react at a low temperature near room temperature, so that a desired catalyst can be obtained. It may not be possible. When producing a catalyst at an industrial level, some measures are required for raw material management and the like in order to avoid moisture.

In the present invention, in order to solve the above-mentioned concerns in the previously proposed catalyst, as the above-mentioned measures, for example, raw materials which are not easily reacted with each other due to moisture and which are relatively inexpensive are used. Focusing on this fact, and further study, the use of aluminum oxide, which is cheaper than aluminum hydroxide, as the component (a) and the addition of (b) the carbonates of the second and third groups of the periodic table and the lanthanoid metal as the component (b) If an oxide is used in place of the salt, a catalyst having the same activity as that of the previously proposed catalyst can be obtained at a lower cost than that of the previously proposed catalyst, and without requiring moisture avoidance or temperature control during catalyst production. I got the knowledge.

The catalyst for producing high-calorie gas of the present invention is based on the above findings, and comprises (a) aluminum oxide;
(B) at least one selected from the group consisting of oxides of Groups 2 and 3 of the periodic table and lanthanoid metals; and (c)
A carrier base material obtained by molding a raw material containing oxyacid and 500
1.5 to 4% by weight of ruthenium is supported on an activated alumina composite carrier obtained by firing at
It is characterized by being subjected to a reduction treatment at 0 ° C. The above catalyst has a ruthenium dispersibility of 60% or more and a carbon monoxide adsorption amount at 50 ° C. of 2.0 ml /
g or more.

Further, the method for producing a catalyst for producing a high calorie gas of the present invention is characterized in that at least one selected from the group consisting of (a) aluminum oxide and (b) oxides of Group 2 and 3 of the periodic table and lanthanoid metals. A carrier substrate obtained by molding a raw material containing one kind and (c) an oxyacid is heated at 500 to 600 ° C.
After loading 1.5 to 4% by weight of ruthenium on the activated alumina composite carrier obtained by calcining at room temperature, ruthenium is insoluble and fixed in an aqueous alkali solution, and then at 80 to 500 ° C.
And the reduction treatment. 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 oxide (activated alumina), (b) an oxide of a metal belonging to Group 2 of the Periodic Table (hereinafter referred to as Group 2), and Group 3 of the Periodic Table (hereinafter referred to as Group 3). Write)
A carrier raw material containing at least one selected from the group consisting of metal oxides and lanthanoid metal oxides and (c) at least one selected from oxyacids is used.

As the aluminum oxide of the component (a),
Normal alumina can be preferably used, but it is desirable to avoid those having extremely small specific surface area such as α-alumina. Specifically, alumina having a specific surface area of about 60 m ² / g or less is not preferable.

In the component (b), Group 2 metal oxides include:
Oxides of beryllium, magnesium, calcium, strontium, barium, and radium can be used, and oxides of magnesium and barium are particularly preferable. As the Group 3 metal oxide, scandium or yttrium oxide can be used, but yttrium oxide is preferable. Lanthanide metal oxides include lanthanum, cerium,
Oxides such as praseodymium, neodymium, promethium and samarium can be used, but cerium and lanthanum oxides are preferred.

These (b) component oxides of Group II, III and lanthanoid metals can be used alone or in combination of two or more. However, there is not much synergistic effect by the combination, and the intended catalytic performance can be obtained by using one kind alone.

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

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

The component (c) is used in powder form.
(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 amount of each component in the carrier material containing the components (a) to (c) is as follows.

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

If the content of the component (b) is less than 5% by weight, it is difficult to obtain a sufficient effect on the sulfur resistance, so that sulfur poisoning and carbon deposition are accompanied, and the catalyst performance is kept stable for a long period of time. Can not. If the content as an oxide is appropriate, the sulfur compound contained in the raw material is Group 2, Group 3,
Since the active ingredient is adsorbed and absorbed by the lanthanoid metal oxide, the active ingredient ruthenium is less likely to be poisoned, and the life is extended. When component (b) exceeds 20% by weight, (a)
The content of alumina as a component relatively decreases. 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 used in an amount of 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 carrier after the calcination of the carrier substrate.
It is. If the amount is less than 1% by weight, the support is not sufficiently made porous, so that not only a desired amount of ruthenium cannot be supported, but also the dispersibility decreases. 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) in preparing the carrier is not particularly limited, and the components (a) and (b) are sufficiently mixed, and the component (c) is added thereto. May be
The component (a) and the component (c) are sufficiently mixed, and
The components may be added, or the components (a) to (c) may be added simultaneously and mixed.

It should be noted that addition of other components such as other metal oxides to the above-mentioned carrier raw material does not hinder the effect of the present invention from being impaired.

The above carrier material is molded into a carrier substrate,
The activated alumina composite carrier is calcined. When the carrier base material contains a solvent or a dispersion medium, it is preferable to completely remove these when the carrier base material is molded. For removal, drying may be performed at normal pressure or reduced pressure, at normal temperature or under heating. When heating and drying, the upper limit is preferably from 90 to 100 ° C. from the viewpoint of not changing the properties of the oxyacid.

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

For the molding, various methods such as pressure molding and extrusion molding can be applied, but pressure molding is preferred. As the pressure molding, tablet molding, injection molding, press molding and the like are mentioned, but in consideration of reaction conditions, tablet molding is preferable. 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 specific surface area of the activated alumina composite carrier obtained as described above is preferably 150 m ² / g or more, and the pore volume is preferably 0.2 to 0.4 ml / g. If the specific surface area or the pore volume of the carrier is less than these values, a desired amount of ruthenium cannot be supported, and the dispersibility of ruthenium also decreases.

The following method is preferred for supporting ruthenium on the above activated alumina composite carrier. First, before supporting ruthenium, the saturated water supply amount of the carrier is determined. That is, the carrier is weighed in advance, and water is applied to the carrier with a burette to absorb water sufficiently to the inside of the carrier, and the saturated water supply amount is measured. Next, an aqueous solution in which a predetermined amount of ruthenium trichloride hydrate is dissolved in ion-exchanged water or distilled water in the same amount as the saturated water supply amount is absorbed by the activated alumina composite carrier.

Thereafter, an excess amount of 7 to 10 N ammonia water is applied to the ruthenium concentration to convert ruthenium chloride to hydroxide as shown in Chemical formula 2, and the ruthenium is insoluble and fixed on the carrier. . 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.

[0043]

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

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

The ruthenium source is not limited to the above-mentioned ruthenium trichloride hydrate, but may be ruthenium trichloride anhydride, ruthenate such as potassium ruthenate, or ruthenium compound such as ruthenium nitrate. 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 supported amount of ruthenium 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.

In the case of activated alumina and activated alumina composite carriers which have been widely used as catalyst carriers, the specific surface area and the porosity are small, so that a large amount of ruthenium as described above is added to these carriers at once. It could not be carried. For this reason, conventionally, a multi-stage impregnation method such as a two-stage impregnation method or a three-stage impregnation, or an impregnation using a high-concentration ruthenium chloride aqueous solution has been required. However, even with these methods, the rate of ruthenium evaporating to dryness on the catalyst is high, and there has been a concern that the catalyst performance may be impaired.

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-mentioned impregnation is dissolved (the charged amount,
(Mol number) can be supported by one-stage impregnation (this is referred to as ruthenium retention), and a desired amount of ruthenium can be supported with a dispersibility as high as 60% or more.

As described above, in the present invention, after the impregnation operation with the ruthenium solution, the operation of insolubilization / immobilization with an aqueous alkali solution such as ammonia water is performed. A complex of a ruthenium species and an alkali species that are not carried on the substrate (for example, an ammine complex << red >>) is not produced. From this, ruthenium is efficiently carried on the activated alumina composite carrier of the present invention. You can see that it is.

It is desirable that the carrier in which ruthenium is insoluble and immobilized is 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 to perform the drying in the above temperature range instead of immediately performing the reduction treatment after the insoluble / immobilized.

In the drying process, it is extremely reasonable to use a rare gas such as helium or argon, or an inert gas such as nitrogen. Even in the middle, the generation amount of the oxide is very small and does not matter. In the operation in the air, the lower the drying temperature, the more advantageous in terms of suppressing the formation of oxides. However, if 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 thus-obtained ruthenium-supported catalyst is subjected to a reduction treatment at a relatively low temperature, the ruthenium supported uniformly by impregnation (ie, in a highly dispersed state) remains unchanged (ie, in a state of high dispersibility). ) 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.

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

The reduction 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 calcination temperature of the carrier is set to be higher than the steam reforming temperature, and ruthenium having a high melting point (metal Ru has a melting point of 2450 ° C.) is selected as the active metal, so that the steam reforming reaction can be performed. In this case, the heat history of the carrier and the active metal is hardly received.

In the present invention, reduction of the catalyst is theoretically possible at the extremely low temperature of 60 to 80 ° C. described above. It is possible that the active site of the
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 and hydrogen / steam mixed gas are preferable, and hydrogen gas is particularly preferable. The reduction time may be appropriately selected depending on conditions such as the reduction temperature and the amount of gas for the reduction gas.
About 20 hours is practical.

The catalyst of the present invention obtained as described above has a specific surface area of 160 to 180 m ² / g, and an adsorbed amount of carbon monoxide (hereinafter, also referred to as CO) at 50 ° C. Is 2.0 ml / g or more, and the dispersibility of ruthenium metal is an extremely excellent value of 60% or more. This is because 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 a catalyst in which particulate ruthenium is supported in a highly dispersed state, The effect of the ruthenium particles on the surface exposure of the support is small, and the support is sufficiently exposed on the catalyst surface. 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 even if a load is applied to the catalyst due to fluctuations in operating conditions, etc., the catalyst performance is stably maintained for a long time because there are many active points. .

The ruthenium dispersibility in the present invention is a percentage of the number of moles of adsorbed CO of the product catalyst (the catalyst after the reduction treatment) with respect to the number of moles of ruthenium, and is expressed by the equation (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.

[0060]

(Equation 2)

That is, the ruthenium dispersibility (%) is
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, 60% or more of the ruthenium of 1.5 to 4% by weight is an active site that can contribute 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.

Conversely, if the dispersibility of ruthenium is less than 60%, the number of active sites is small, so that the apparent reaction rate decreases. 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-mentioned catalyst of the present invention has sufficient mechanical strength, is excellent in sulfur poisoning resistance, and shows good reaction results close to the equilibrium addition rate. Therefore, the catalyst of the present invention exhibits good steam reforming activity even with a raw material containing a sulfur compound.

The hydrocarbon which is the main component of the raw material when producing a high calorie gas with the catalyst of the present invention has 2 to 16 carbon atoms, preferably 2 to 10 carbon atoms, more preferably 3 to 3 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.

[0066]

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
The separation was performed by a gas chromatograph (GC-9A, trade name, manufactured by Shimadzu Corporation) equipped with a thermal conductivity type detector (TCD) equipped with a separation column packed with L Science Co., Ltd. trade name. 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).

Example 1 Cerium oxide (CeO ₂ , manufactured by Kanto Chemical) powder 3.75
g, activated alumina powder (Al ₂ O ₃ , manufactured by Merck)
5g, and tartaric acid _{(C 2} H 6 _{O 4,} manufactured by Kanto Kagaku) powder 21.4 g, was sufficiently mixed in an agate mortar. This powder (200 mesh) was pressed at a molding pressure of 20 with a tableting machine (model FK-1, trade name of Systems Engineering Co., Ltd.).
It was molded into a columnar shape (pellet) having a diameter of 3.2 mmφ at a ton / cm ² , and calcined in air in a muffle furnace at 600 ° C. for 3 hours to obtain a carrier pellet. The gas generated during firing was exhausted into a draft chamber using a water jet pump provided with an exhaust pipe in a muffle furnace. The specific surface area of the composite carrier thus obtained was 210 m ² / g, and the pore volume was 0.35 ml / g.

3 g of ruthenium trichloride monohydrate (manufactured by Mitsuwa Chemicals, ruthenium content: 44 to 45 wt%) is dissolved in water to make 100 ml, and 22.1 g of the above carrier pellets are added to 25 ml of this aqueous solution at room temperature for 1 hour. Soaked. After removing the residual liquid from the pellets removed from the aqueous solution, about 2.7 kPa (about 20 mmHg) using 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 pellet was sufficiently washed with ion-exchanged water. Washing was performed by adding a dilute silver nitrate aqueous solution dropwise to a part of the filtrate until silver chloride precipitation (white or gray) no longer occurred. The washed pellets are placed in a vacuum dryer at 40-45.
Dry at 8 ° C for 8-10 hours. 10ml pellet after drying
Was charged into a normal pressurized flow reactor, and a pressure of 0.78
MPa (8 kg / cm ² G), reduction temperature 150 ° C, GH
The catalyst A was obtained by reduction with hydrogen controlled at a flow rate of a mass flow controller at SV900 (v / v) h ^-1 for 8 hours.

The catalyst A was composed of 1.5 wt% of ruthenium, 7.5 wt% of cerium oxide and the remaining alumina, having a specific surface area of 205 m ² / g and a breaking strength (DWL) of 26.0 k.
g. The CO adsorption amount was 2.7 ml / g (STP: standard state converted value). This value indicates the amount of adsorption on ruthenium, since no CO adsorption was observed only on the carrier not supporting ruthenium. The ruthenium dispersibility was 80% as a result of calculation using the equation (2).
The properties of Catalyst A are summarized in Table 1.

Next, a commercially available L was charged into the reactor filled with the catalyst A.
PG gas (Cosmo Oil's trade name Cosmobutane Silver,
C3: 3 vol%, iso-C4: 32 vol%, n-
(C4: 65 vol%) and 10 ppm of hydrogen sulfide added thereto were introduced together with steam, and the LPG gas was subjected to a steam reforming reaction to produce SNG. The reaction conditions were a pressure of 0.78 MPa (8 kg / cm ² G) and a reaction temperature of 450.
C, GHSV600 (v / v) h ^-1 and S / C ratio of 1. The reaction results are shown in Table 2.

Example 2 The procedure of Example 2 was repeated except that 3.75 g of cerium oxide powder, 45.1 g of activated alumina powder (same as in Example 1), and 5.56 g of tartaric acid powder (same as in Example 1) 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 was 190 m ² / g, and the pore volume was 0.36 ml / g.

The same procedure as in Example 1 was carried out except that 25 ml of water containing 1.15 g of ruthenium trichloride monohydrate (the same as in Example 1) was immersed in 22 g of the above carrier pellets and the reduction temperature was set to 450 ° C. Similarly, catalyst B was prepared. Catalyst B
Is ruthenium 2.3 wt%, cerium oxide 7.5 wt
%, The balance being alumina, and a specific surface area of 180 m ² / g,
Breaking strength 26.0 kg, CO adsorption amount 4.1 ml / g (S
TP) and the ruthenium dispersibility was 80%. The properties of Catalyst B are summarized in Table 1, and the results of the same steam reforming reaction as in Example 1 performed using Catalyst B are shown in Table 2.

Example 3 Yttrium oxide (Y ₂ O ₃ , manufactured by Soekawa Chemical) powder 2.5
g, activated alumina powder (same as in Example 1) 46.4
g, and tartaric acid powder (same as in Example 1) 3.68
A composite carrier (pellet) was prepared in the same manner as in Example 1 except that g was used. The specific surface area of the obtained composite carrier was 220 m ² / g, and the pore volume was 0.37 ml / g.

The same procedure as in Example 1 was carried out except that 25 ml of water containing 1.15 g of ruthenium trichloride monohydrate (same as in Example 1) was immersed in 22 g of the above carrier pellets and the reduction temperature was set to 80 ° C. Similarly, catalyst C was prepared. Catalyst C
Is 2.3 wt% ruthenium, 5 wt% yttrium oxide
%, The remainder being alumina, specific surface area 209 m ² / g,
Breaking strength 27.5kg, CO adsorption 3.9ml / g (S
TP), and the ruthenium dispersibility was 77%. 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 6 g of lanthanum oxide (La ₂ O ₃ , manufactured by Wako Pure Chemical Industries) powder, 42.5 g of activated alumina powder (same as in Example 1), and tartaric acid powder (same as in Example 1) A (pellet) was prepared in the same manner as in Example 1 except that 49 g was used. The specific surface area of the obtained composite carrier is 171 m ² /
g, pore volume was 0.34 ml / g.

The same procedure as in Example 1 was carried out except that 22 ml of the above carrier pellets were immersed in 25 ml of water containing 1.51 g of ruthenium trichloride monohydrate (the same as in Example 1) to reduce the reduction temperature to 400 ° C. Similarly, catalyst D was prepared. Catalyst D
Is composed of 3 wt% of ruthenium, 12 wt% of lanthanum oxide and the remaining alumina, having a specific surface area of 163 m ² / g, a breaking strength of 27.5 kg, and a CO adsorption amount of 4.8 ml / g (ST
P), the ruthenium dispersibility was 72%. The properties of the catalyst D are summarized in Table 1, and the results of the same steam reforming reaction as in Example 1 performed using the catalyst D are shown in Table 2.

Example 5 10 g of magnesium oxide (MgO, manufactured by Wako Pure Chemical Industries) powder,
A (pellet) was prepared in the same manner as in Example 1 except that 38 g of activated alumina powder (the same as in Example 1) and 50 g of tartaric acid powder (the same as in Example 1) were used. The specific surface area of the obtained composite carrier is 215 m ² / g,
The pore volume was 0.38 ml / g.

The same procedure as in Example 1 was carried out except that 22 ml of the above carrier pellets were immersed in 25 ml of water containing 2.03 g of ruthenium trichloride monohydrate (the same as in Example 1) to lower the reduction temperature to 450 ° C. Similarly, catalyst E was prepared. Catalyst E
Is ruthenium 4wt%, magnesium oxide 20wt
%, The balance being alumina, specific surface area 207 m ² / g,
Breaking strength 25.0kg, CO adsorption 5.5ml / g (S
TP), and the ruthenium dispersibility was 62%. Properties of Catalyst E The results are shown in Table 1 and are shown in Table 1.
Table 2 shows the results of the steam reforming reaction similar to the above.

Example 6 3.75 g of barium oxide (BaO, manufactured by Wako Pure Chemical Industries) powder,
Activated alumina powder (same as in Example 1) 44.3 g,
And tartaric acid powder (same as in Example 1) 116.7 g
In the same manner as in Example 1 except that
Was prepared. The specific surface area of the obtained composite carrier is 217 m
² / g and the pore volume was 0.41 ml / g.

The same procedure as in Example 1 was carried out except that 22 ml of the above carrier pellets were immersed in 25 ml of water containing 2.03 g of ruthenium trichloride monohydrate (the same as in Example 1) to reduce the reduction temperature to 500 ° C. Similarly, catalyst F was prepared. Catalyst F
Is 4 wt% ruthenium, 7.5 wt% barium oxide,
Remaining alumina, specific surface area 210 m ² / g, breaking strength 24.5 kg, CO adsorption amount 5.3 ml / g (ST
P), the ruthenium dispersibility was 60%. The properties of the catalyst F are summarized in Table 1 and the results of the same steam reforming reaction as in Example 1 performed using the catalyst F are shown in Table 2.

Comparative Example 1 35 g of activated alumina powder (same as in Example 1) was tabletted into 3.2 mmφ pellets in the same manner as in Example 1 and calcined in the same manner as in Example 1 to give a specific surface area of 110 m ²
/ G, and an alumina support having a pore volume of 0.18 ml / g. 25 ml of water containing 1.75 g of ruthenium trichloride monohydrate (the same as in Example 1) was immersed in 22.3 g of the carrier, and after removing the residual liquid, the residue was washed with pure water and dried at 110 ° C. for 5 hours. Thus, catalyst G was prepared. The catalyst G was composed of 2.3 wt% of ruthenium and the remaining alumina, and had a specific surface area of 49 m.
2 / g, breaking strength 24.5kg, CO adsorption 1.8ml
/ G, and the ruthenium dispersibility was 35%. The properties of the catalyst G are summarized in Table 1 and the results of the same steam reforming reaction as in Example 1 performed using the catalyst G are shown in Table 2.

The conversion and selectivity shown in Table 2 are as follows:
Calculated from the formula shown in

[0084]

(Equation 3)

[0085]

[Table 1-1]

[0086]

[Table 1-2]

[0087]

[1 of Table 2]

[0088]

[Table 2-2]

As is clear from Table 1, the ruthenium dispersibility was 35% in Comparative Example 1, whereas that of Examples 1 to
In No. 6, it is 60 to 85%, which is 1.7 times or more improved. Further, the specific surface area is 49 m ² / g in Comparative Example 1, whereas the specific surface area is 160 m ² / g or more in Examples 1 to 6, indicating an improvement effect of three times or more. From these facts, in the conventional catalyst, ruthenium supported on the catalyst surface is present in the form of chloride or oxide which is difficult to be reduced, so that it is difficult for Ru to be converted to Ru ⁰ even after hydrogen reduction treatment. It can be seen that they exist considerably densely, and the dispersibility of Ru ⁰ is low. On the other hand, the catalyst of the present invention is insoluble / immobilized in the form of Ru (OH) ₃ which is easily reduced to Ru ⁰ , and further, when the chlorine anion is dissolved in the soluble salt ( Ammonium chloride)
There is almost no effect of residual chlorine. Moreover, the addition of the oxyacid to the carrier material makes the carrier porous,
The dispersibility of u ⁰ is high.

As is clear from Table 2, the conversion and selectivity of the conventional catalyst are low. This is because the active sites (Ru ⁰ ) were small as described above, and thus the raw materials were easily poisoned by hydrogen sulfide. If the number of active sites is merely low, a decrease in only the conversion should be observed, but in Table 2, the selectivity is reduced to the order of 50%. This is the result of Ru ⁰ poisoning by hydrogen sulfide, which triggered carbon deposition. On the other hand, in the catalyst of the present invention, in addition to alumina, 2
It is considered that the addition of the oxides of Group III, III, and lanthanoid metals protects the active sites by adsorbing and absorbing sulfur compounds, so that the conversion and the selectivity are high.

As described above, according to the present invention, a desired amount of Ru can be highly dispersed and supported on a carrier having a practical level of strength, and the carrier has a function of absorbing and adsorbing a sulfur compound. be able to. Therefore, the use of the catalyst of the present invention makes it possible to stably produce SNG for a long period of time. Further, since the number of active points is sufficient, it is possible to sufficiently cope with fluctuations in operating conditions, shutdown of a plant, and the like.

[0092]

According to the present invention, it is possible to provide a catalyst having a practical level of strength and having both sulfur poisoning resistance and carbon deposition resistance.
In an industrial process for producing NG, excellent reaction results with high selectivity and high conversion can be stably maintained for a long period of time.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Takashi Yoshizawa, Inventor 1134-2 Gongendo, Satte City, Saitama Pref.

Claims (5)

[Claims] 1. A raw material containing (a) aluminum oxide, (b) at least one selected from the group consisting of oxides of Groups 2 and 3 of the periodic table and lanthanoid metals, and (c) an oxyacid. 500-600 ° C.
A high-calorie gas production catalyst comprising 1.5 to 4% by weight of ruthenium supported on an activated alumina composite carrier obtained by calcining at 80 to 500 ° C. 2. The catalyst for producing a high calorie gas according to claim 1, wherein the ruthenium dispersibility is 60% or more. 3. The amount of carbon monoxide adsorbed on the catalyst is 50 ° C.
3. The high calorie gas producing catalyst according to claim 1, wherein the catalyst is 2.0 ml / g or more in terms of standard condition. 4. A raw material containing (a) aluminum oxide, (b) at least one selected from the group consisting of oxides of Groups 2 and 3 of the periodic table and lanthanoid metals, and (c) an oxyacid. 500-600 ° C.
After loading 1.5 to 4% by weight of ruthenium on the activated alumina composite carrier obtained by calcining at room temperature, ruthenium is insoluble and fixed in an aqueous alkali solution, and then at 80 to 500 ° C.
For producing a catalyst for producing high calorie gas, which is subjected to a reduction treatment with a catalyst. 5. The method for producing a catalyst for producing high calorie gas according to claim 4, wherein the catalyst is dried at 100 ° C. or lower under reduced pressure or normal pressure prior to the reduction treatment.