JPH0822378B2 - Hydrocarbon steam reforming catalyst - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hydrocarbon steam reforming catalyst, and more specifically, a hydrocarbon having excellent properties such as high catalytic activity and long catalyst life. The present invention relates to a steam reforming catalyst.

[Problems to be Solved by Conventional Techniques and Inventions] Various catalysts have hitherto been used as a catalyst for reacting a hydrocarbon with steam to promote a steam reforming reaction for conversion into hydrogen, carbon monoxide, methane, and carbon dioxide. JP-B-39-29435 discloses a catalyst for steam reforming of hydrocarbon in which a platinum group metal is supported on a heat-resistant oxide.

In JP-A-57-50533, the volume of pores having a pore size in the range of 60 to 120Å is 0.35 ml / g or more, and the pore size is 120Å.
Disclosed is an alumina porous body carrying nickel oxide, characterized in that the volume of the pores is 0.1 ml / g or more.

JP-A-59-112840 discloses that in the total pore volume of the carrier, 1
Disclosed is a catalyst composition for producing a fuel gas, which uses a carrier in which the pore volume of macropores having a pore diameter of 00 to 10,000Å is 40% or more of the total pore volume.

However, all of these conventional catalysts have a new problem that they cannot fully meet the industrial requirements of higher activity and longer life.

It is an object of the present invention to provide a hydrocarbon steam reforming catalyst having high activity and long life.

By the way, in various proposals regarding a catalyst for steam reforming of hydrocarbons, although the relationship between the catalyst activity and the pore distribution has been examined, the relationship between the catalyst life and the pore distribution has been sufficiently examined. Absent.

Therefore, as a result of detailed study on the relationship between the pore distribution and the catalyst activity and the catalyst life, the present inventors have found that the optimum pore distribution of the catalyst carrier required to maintain high activity and achieve a long life. Therefore, the present invention has been completed.

[Means for Solving the Problems] The present invention for solving the problems described above, the volume of pores having a pore diameter of 500 Å or less is 0.15 ml / g or more, and the volume of pores having a pore diameter of 500 Å or more is 0.14. A catalyst for steam reforming of hydrocarbons, characterized in that a platinum group metal is supported on a carrier having an average pore size of 90 Å or more in the range of ml / g or less.

 The present invention will be described in detail below.

Carrier The carrier in the present invention is not particularly limited as a material as long as it has sufficient durability in a hydrocarbon steam reforming reaction, preferably in the reaction and a catalyst regeneration atmosphere, and can be used as a catalyst carrier. Oxides (including simple oxides, oxide-based materials such as complex oxides and oxide-based compositions), non-oxide-based materials, materials composed of oxides and non-oxides, or these It is possible to use a mixture of various materials such as a mixture of.

Among these, usually, a heat-resistant oxide carrier, which is a carrier made of a heat-resistant oxide (including oxide-based substances as described above), is preferably used.

Examples of the heat-resistant oxide carrier include various types of
Examples thereof include alumina, magnesia, silica, zeolite, titania, zirconia or stabilized zirconia, yttria, silica alumina, alumina boria, silica titania, silica zirconia, and the like, or a carrier containing these as the main components.

Among the various heat-resistant oxide carriers, zirconia-based carriers are particularly preferable. As this zirconia-based carrier,
Examples thereof include a zirconia carrier, a stabilized zirconia carrier and other zirconia-containing carriers. Among these zirconia-based carriers, usually, zirconia carrier,
A stabilized zirconia carrier can be preferably used.

In addition, the above-mentioned heat-resistant oxide carrier may contain various impurities and additive components within a range not hindering the purpose of the present invention.

Also, these carriers may be used alone,
You may use together 2 or more types as a mixture, a composite, etc.

As the zirconia carrier, zirconium oxide (Zr
O ₂ ) can be preferably used, but a carrier containing this as a main component can also be used in the present invention. Furthermore,
A substance that can be converted into zirconium oxide or a substance containing this as a main component during catalyst preparation or steam reforming reaction can also be included in the zirconia carrier in the present invention.

As the zirconium oxide, any of commercially available products and preparations other than commercially available products can be used.

Examples of the substance that is converted to zirconium oxide during catalyst preparation or steam reforming reaction include zirconium hydroxide, zirconium halide such as zirconium chloride, zirconium oxyhalide such as zirconium oxychloride, zirconium nitrate, zirconyl nitrate, and the like. Examples thereof include organic acid zirconium such as zirconium acetate and zirconium oxalate, organic acid zirconyl such as zirconyl acetate, zirconium alkoxide, and organic zirconium compound.

Incidentally, the sparingly soluble compound in the various compounds,
It can also be used after being solubilized by adding an acid or the like as appropriate.

The various zirconium compounds may be used alone or in combination of two or more.

The stabilized zirconia carrier can be obtained by modifying and stabilizing the zirconia component by adding a stabilizer.

As the zirconia component of the stabilized zirconia carrier, the zirconia carrier can be used as it is, and the zirconia component can be obtained from various zirconium compounds such as the zirconium oxide.

Examples of the stabilizer include yttrium oxide component, magnesium oxide component, cerium oxide component, or various known oxide components used as a stabilizing component of so-called stabilized zirconia.

Among these, the yttrium oxide component, the magnesium oxide component and the cerium oxide component can be particularly preferably used.

The yttrium oxide component, the magnesium oxide component and the cerium oxide component can be formally represented as Y ₂ O ₃ , MgO and CeO ₂ , respectively.

Examples of the yttrium source used as a raw material for preparing the yttrium oxide component include yttrium oxide or a substance that can be converted to yttrium oxide (yttrium oxide component) during catalyst preparation or steam reforming reaction.

As a substance converted to the yttrium oxide component,
For example, yttrium hydroxide, yttrium halide, yttrium oxyhalide, yttrium nitrate, yttrium carbonate and other inorganic acid salts of yttrium, yttrium acetate, yttrium oxalate and other organic acid salts of yttrium, yttrium trimethoxide, yttrium triethoxy De, yttrium tripropoxide,
Examples thereof include yttrium alkoxides such as yttrium triisopropoxide and yttrium tributoxide.

Among these, yttrium alkoxide and the like can be preferably used.

As the magnesium source used as a raw material for preparing the magnesium oxide component, magnesium oxide or a substance that can be converted into magnesium oxide (magnesium oxide component) during catalyst preparation or steam reforming reaction can be used.

As a substance that is converted to the magnesium oxide component,
For example, magnesium hydroxide, magnesium halide, magnesium nitrate, magnesium carbonate and other inorganic acid salts, magnesium acetate, magnesium oxalate and other magnesium organic acid salts, magnesium methoxide, magnesium ethoxide, magnesium propoxide, magnesium Examples thereof include magnesium alkoxide such as isopropoxide and magnesium butoxide.

Of these, magnesium alkoxide and the like can be preferably used.

As the cerium source used as a raw material for preparing the cerium oxide component, cerium oxide or a substance that can be converted into cerium oxide (cerium oxide component) during catalyst preparation or steam reforming reaction can be used.

Examples of the substance which is converted into the cerium oxide component include cerium hydroxide, cerium halide, cerium oxyhalide, cerium nitrate, cerium carbonate, and other inorganic acid salts of cerium, cerium acetate, cerium oxalate, and other organic cerium salts. Examples thereof include acid salts, cerium methoxide, cerium ethoxide, cerium propoxide, cerium isopropoxide, and cerium alkoxides such as cerium butoxide.

Among these, cerium alkoxide and the like can be preferably used.

These yttrium compounds, magnesium compounds and cerium compounds may be used alone or in a combination of two or more.

The sparingly soluble compound can be used after being solubilized by appropriately adding alcohol or acid.

Of importance in the present invention, among the carriers such as the heat-resistant oxide carrier, the volume of pores having a pore size of 500 Å or less is 0.15 ml / g or more, preferably 0.17 ml / g or more, and the pore size is Has a volume of pores of 500Å or more of 0.14 ml / g or less, preferably in the range of 0.10 ml / g or less, and the average pore diameter is
The carrier is selected and used in the range of 90Å or more, preferably 90 to 350Å.

In addition, in the present invention, the value of the pore diameter of the carrier and the value of the volume pore of the pore are the values when the pore distribution is measured in the range of 30 to 3.5 × 10 ⁵ Å by the mercury penetration method.

That is, the value of the pore diameter of the carrier or its range and the volume of the pores referred to in the present invention are defined based on the pore distribution in the pore diameter range of 30 to 3.5 × 10 ⁵ Å measured by the mercury porosimetry. It was done.

Therefore, when the pore diameter is said to be 500 Å or less or 500 Å or more, the values and ranges of these pore diameters are the values and ranges of the pore diameters measured by the mercury intrusion method (30 to 3.
5x10 ⁵ Å), and also,
Even if it is said that the volume of pores having a pore diameter of 500 Å or less, the value of this volume (for example, 0.15 ml / g, 0.17 ml / g)
It should be noted that even if there are small pores having a pore size of less than 30Å, the volume of pores having a pore size of less than 30Å is not included. Similarly, even if it is said that the volume of pores having a pore diameter of 500 Å or more, the value of this volume is such that even if there are large pores with a pore diameter of more than 3.5 x 10 ⁵ Å, It should be noted that the volume of pores with a pore size of more than 3.5 × 10 ⁵ Å is not included.

That is, the carrier used in the present invention is not particularly limited in terms of the volume of small pores and large pores which are not within the range of 30 to 3.5 × 10 ⁵ Å measured by the mercury porosimetry.

In the present invention, the conditions relating to the pores of the carrier are important in order to control the diffusion rate of the reaction substance and the like, and to realize high activity and long life.

This means that the volume of pores with a pore diameter of 500Å or less
High activity cannot be obtained unless it is 0.15 ml / g or more and the average pore size is 90Å or more. Further, unless the volume of pores having a pore diameter of 500 Å or more is 0.14 ml / g or less, high activity cannot be stably maintained and the catalyst life becomes short.

The special carrier having such pore characteristics can be prepared as follows.

For example, in the precipitation method, there is a method of growing the precipitation particles by raising and lowering the pH at the time of forming the precipitate, and finally changing the pore diameter of the carrier (for example, see JP-A-56-120508), In the powder method, there is a method of controlling the particle size by sintering the powder particles and finally changing the pore size of the carrier.

The shape of the carrier is not particularly limited, and for example,
It may be in any shape such as fine powder, granules, beads, pellets, plates, films and monoliths.

Supported component The catalyst for steam reforming of hydrocarbon of the present invention is a carrier having the specific pore characteristics (generally, the heat-resistant oxide carrier,
Preferably, the platinum group metal is supported on the zirconia-based carrier, particularly preferably the zirconia carrier or the stabilized zirconia carrier).

Examples of the platinum group metal include ruthenium, rhodium, palladium, osmium, iridium and platinum. Among these, ruthenium and rhodium are preferable, and ruthenium is particularly preferable.

In addition, these can be used alone,
Two or more kinds can be used in combination.

As the ruthenium source supported on the carrier, for example,
Ruthenium iodide, ruthenium halide such as ruthenium chloride, ruthenium chloride such as ruthenium chloride, ammonium ruthenate chloride, potassium ruthenate chloride, ruthenium chloride such as sodium ruthenate chloride, ruthenium hydroxide, ruthenium dioxide, Ruthenium oxide such as ruthenium tetraoxide, ruthenium potassium oxide, ruthenium oxide such as ruthenium sodium oxide,
Examples thereof include organic ruthenium compounds such as ruthenium carbonyl and metallic ruthenium such as ruthenium colloid.

Such ruthenium sources can be used alone or in combination of two or more.

Among these, ruthenium trichloride is preferable.

As a rhodium source for supporting the rhodium metal, for example, a rhodium halide such as rhodium chloride,
Rhodium halides such as rhodium chloride, ammonium rhodium chloride, sodium rhodium chloride, rhodium salts such as potassium rhodate, rhodium hydroxide (III), rhodium hydroxide (IV), rhodium nitrate, rhodium oxide, Examples thereof include organic rhodium such as rhodium carbonyl and metallic rhodium such as rhodium colloid.

Such rhodium sources can be used alone or in combination of two or more.

The amount of the platinum group metal supported in the hydrocarbon steam reforming catalyst of the present invention cannot be uniformly determined because it varies depending on other conditions such as the type and composition of the metal used, or the type of carrier, but Is suitably in the range of 0.01 to 5% by weight. For example, in the case of supporting ruthenium and / or rhodium which are preferable as the platinum group metal, the total supported amount of ruthenium or rhodium or ruthenium and rhodium may be appropriately selected from the range of 0.01 to 5% by weight, When the zirconia carrier or the stabilized zirconia carrier is used as the carrier, the amount of ruthenium and / or rhodium supported is usually 0.05 to 3.0% by weight, preferably 0.1 to 2.0% by weight.

If the amount of platinum group metal supported is less than 0.01% by weight, it may not function as a catalyst. Further, even if the amount is more than 5% by weight, the technical effect commensurate with the increase may not be obtained.

The catalyst for steam reforming of hydrocarbons of the present invention, in addition to the platinum group metal (main catalyst component) such as ruthenium and / or rhodium, carries a cocatalyst component composed of an element imparting a cocatalyst function. By supporting an appropriate promoter component, the activity and catalyst life of the hydrocarbon steam reforming catalyst can be further improved.

Various elements can be used as the element that is the co-catalyst component (element that imparts the co-catalyst function), but in particular,
Cobalt and / or manganese are preferred. That is, in the hydrocarbon steam reforming catalyst of the present invention, the carrier (preferably zirconia-based carrier, particularly preferably zirconia carrier or stabilized zirconia carrier) is loaded with a platinum group metal (particularly preferably ruthenium),
It is preferable to carry cobalt and / or manganese as an element that imparts a promoter function.

It should be noted that cobalt and manganese can be used each alone or in combination.

As the cobalt and manganese sources, inorganic salts such as halides, sulfates, nitrates and carbonates of these metals,
Examples thereof include organic acid salts such as acetates, hydroxides, oxides, basic salts, alkoxides and organic compounds.

Specific examples of the cobalt source include cobalt chloride (hexahydrate), cobalt chloride (anhydride), cobalt nitrate, cobalt sulfate, cobalt acetate, cobalt formate, cobalt oxalate, cobalt hydroxide, cobalt oxide, cobalt carbonate ( Basic cobalt carbonate), cobalt (II) acetylacetonate, cobalt (III) acetylacetonate, cobalt carbonyl and the like.

 Of these, cobalt nitrate is preferable.

The specific example of the manganese source will be apparent by replacing “cobalt” with “manganese” in the specific example of the cobalt source.

 The manganese source is preferably manganese nitrate.

The supported amount of the co-catalyst component is the type and composition of the supported component,
Or because it depends on other conditions such as the type of carrier,
It may be appropriately selected in consideration of such conditions. For example, when a zirconia carrier or a stabilized zirconia carrier is used as the carrier, the various cobalt sources and / or
Or, the supported amount of the promoter component obtained from the manganese source is
The carrier is usually 1.0 to 10.0% by weight, preferably
It is suitable to be 1.0 to 5.0% by weight.

The supported amount (% by weight) is a value calculated when cobalt and manganese are used as elements, and when both are supported, the total amount thereof is represented.

When the amount of cobalt and / or manganese added is within the above range, it is possible to easily reduce the deterioration rate while maintaining high activity.

Further, the catalyst for steam reforming of hydrocarbon of the present invention can further maintain high activity and stabilize it by supporting potassium and / or barium together with cobalt and / or manganese.

That is, the hydrocarbon steam reforming catalyst of the present invention,
More preferably, the carrier (preferably a zirconia-based carrier, particularly preferably a zirconia carrier or a stabilized zirconia carrier) is loaded with a platinum group metal (particularly preferably ruthenium), cobalt and / or manganese, and potassium and / or barium. More preferable.

As a potassium source and a barium source for supporting potassium and / or barium on the catalyst carrier, inorganic acid salts such as halides, sulfates, nitrates and carbonates of these metals (neutral salts, acidic salts, basic salts) can be used. Salts), organic acid salts such as acetates, hydroxides, oxides, alkoxides, organic compounds and the like.

Specific examples of the potassium source include, for example, potassium chloride, potassium nitrate, potassium sulfate, potassium carbonate,
Examples thereof include potassium acetate, potassium hydroxide and potassium alkoxide.

Among these, potassium nitrate and the like are preferable.

Specific examples of the barium source, for example, barium chloride, barium nitrate, barium sulfate, barium carbonate,
Examples thereof include barium hydroxide.

Of these, barium nitrate and the like are preferable.

A suitable addition amount (support amount) of potassium and / or barium differs depending on other conditions such as the type and composition of the supported component, the type of carrier, etc., and may be appropriately selected in consideration of such conditions. .

For example, when using a zirconia carrier or a stabilized zirconia carrier as a carrier, the supported amount of the additive component obtained from the various potassium sources and / or barium sources is usually 0.01 to 2.5% by weight relative to the carrier, It is suitable to be 0.01 to 1.0% by weight.

The supported amount (% by weight) is a value when potassium and barium are calculated as elements, and when both are supported, the total amount thereof is represented.

When the amount of potassium and / or barium added is in the above range, it is possible to sufficiently achieve the effect of further improving the above-described effect of adding cobalt and / or manganese.

Catalyst Preparation The method for preparing the hydrocarbon steam reforming catalyst of the present invention is not particularly limited and includes, for example, an impregnation method, an ion exchange method, a wet adsorption method, a dry adsorption method, a CVD method,
Various methods such as a solvent evaporation method, a dry mixing method, a wet mixing method, and a spray coating method, and a combination method thereof can be appropriately adopted, and a stationary method can also be used as an operation method for supporting. Various methods such as a method, a stirring method, a solution flow method, and a solution reflux method can be appropriately adopted.

The obtained catalyst can be appropriately subjected to a calcination treatment such as an oxidation treatment, a reduction treatment, a modification treatment or a pretreatment (such as an activation treatment) and then used for the reaction.

Hydrocarbon Steam Reforming Reaction The hydrocarbon steam reforming catalyst of the present invention is used to accelerate a hydrocarbon steam reforming reaction.

The hydrocarbon is not particularly limited and includes, for example, methane, ethane, propane, butane, pentane, hexane,
Examples include linear or branched saturated aliphatic hydrocarbons such as heptane, octane, nonane, and decane (usually having about 1 to 10 carbon atoms), and alicyclic saturated hydrocarbons such as cyclohexane, methylcyclohexane, and cyclooctane. be able to.

The hydrocarbon may be one kind among the above-mentioned various kinds, may be a mixture of two or more kinds, and may be various refined petroleum fractions.

It is considered that the hydrocarbon reacts with water vapor according to the following reaction formula.

C _n H _m + nH ₂ O → nCO + (n + m / 2) H ₂ (I) C _n H _m + 2nH ₂ O → nCO ₂ + (2n + m / 2) H ₂ (II) [wherein formula (I) and formula (I In II), n represents a real number of 1 or more and m represents a real number of 2 or more. ] In addition to the above, CH by hydrocarbon hydrocracking, etc.
₄ generation and reaction (III) _{of, C n H m + [(} 1/2) - (m-4n) / 4] H 2 O → [2n- (2 + m) / 4] CH 4 + [(1/2 )-(M-4n) /
4] CO + H ₂ (III) Further, the following equilibration reaction CH ₄ + H ₂ O CO + 3H ₂ (IV) CO + H ₂ O CO ₂ + H ₂ (V) may occur simultaneously.

Therefore, theoretically, the amounts of the hydrocarbon and steam used can be determined by the stoichiometric amount so as to follow the above reaction formulas (I) to (V), but when the catalyst of the present invention is used, Steam / carbon ratio is usually 1-12,
It is preferable to determine the amount of hydrocarbons and the amount of water vapor so as to be preferably 2 to 8.

By adopting this steam / carbon ratio, a hydrogen-rich gas can be obtained particularly efficiently and stably.

The reaction temperature is usually 500 to 900 ° C., preferably 65.
0 to 850 ° C.

The reaction pressure is usually 0 to 50 kg / cm ² G, preferably 0 to
It is 20 kg / cm ² G.

The reaction system may be either a continuous flow system or a batch system, but the continuous flow system is preferred.

The reaction system is not particularly limited and may be a fixed bed system, a fluidized bed system, or the like.

The form of the reactor is not particularly limited, and for example, a tubular reactor can be adopted.

Thus, in the presence of the catalyst of the present invention, hydrocarbons and steam are reacted to produce hydrogen, carbon monoxide, methane,
A mixed gas containing and carbon dioxide can be produced.

This mixed gas can be directly used for various purposes, or can be separated into each gas component and provided for each purpose.

[Examples] Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these Examples, and various modifications can be made without departing from the concept of the present invention. And application is possible.

Examples 1-9 and Comparative Examples 1-5 Preparation of Catalyst Support and Catalyst Preparation of Catalyst B 80.6 g zirconyl chloride (zirconium oxychloride)
Was dissolved in 1.5 l of distilled water and heated to 60 ° C (solution).
Separately, add distilled water to 58.3 ml of ammonia water and add 583 ml.
Was prepared (solution). To the solution of 1 was added 200 ml of solution to bring the pH to 5.4 and a precipitate of zirconium hydroxide was formed.

Then, 140 ml of the remaining solution was further added to bring the pH to 3.1. Then, 30 ml of solution and 140 ml of solution were added alternately, and the pH was changed (swinging) three times between 5 and 3.

Finally, the remaining amount of the solution was added to adjust the pH to 8.5, and the mixture was aged for 90 minutes.

The precipitate thus obtained was filtered and washed with 20 l of distilled water. After the washed cake was dried at 120 ° C. for 5 hours, it was further baked at 500 ° C. for 1 hour.

25 g of the obtained zirconia was added to RuC containing 0.125 g as Ru.
Ruthenium is supported on zirconia by impregnating it with an aqueous solution containing l ₃ .3H ₂ O, dried at 120 ° C. for 6 hours, and then calcined at 500 ° C. for 1 hour to form catalyst B. Prepared.

The amount of ruthenium supported on the catalyst B was 0.5% by weight.

Preparation of catalyst A Catalyst A was prepared in the same manner as the preparation of catalyst B except that the solution was simply added to the solution.

Preparation of catalyst C A catalyst C was prepared in the same manner as the preparation of the catalyst B except that the pH was repeatedly changed (swing) 6 times.

Preparation of catalyst D Same as preparation of catalyst B above, except that zirconia “RC-100” manufactured by Daiichi Rare Elements Industry Co., Ltd. was previously calcined at 500 ° C. for 1 hour as a zirconia carrier. Then, a catalyst D was prepared.

Preparation of catalyst G A catalyst G was prepared in the same manner as the preparation of the catalyst D except that zirconia "RC-50" manufactured by Daiichi Rare Elements Industry Co., Ltd. was used instead of the zirconia "RC-100".

Preparation of catalyst H A catalyst H was prepared in the same manner as the preparation of the catalyst D except that zirconia “EP grade” manufactured by Daiichi Rare Elements Industry Co., Ltd. was used instead of the zirconia “RC-100”.

Preparation of catalyst I Stabilized zirconia "NY-8" manufactured by Nippon Shokubai Chemical Industry Co., Ltd.
Catalyst I was prepared in the same manner as catalyst D above except that "Y" was used.

Preparation of catalyst E Zirconyl nitrate (zirconium oxynitrate) at room temperature
Solution of 1 in which 142.9g was dissolved, 27g of ammonium carbonate and 25g of ammonia water (28%) were distilled water 500m
a solution (solution) dissolved in l in 200 ml of distilled water,
At the same time, a predetermined dropping rate was added so that the pH was maintained at 4, and the mixture was stirred for 30 minutes to obtain a precipitate. After that, it was filtered and washed with 2 l of distilled water to obtain a cake. A catalyst E was prepared in the same manner as the preparation of the catalyst B, except that this cake was used instead of the cake in the preparation of the catalyst B.

Preparation of catalyst F A catalyst F was prepared in the same manner as the preparation of the catalyst E except that the pH was adjusted to 6 at the time of mixing the solution in the preparation of the catalyst E.

Preparation of catalyst J After drying at 120 ° C, tablet molding was performed, and the obtained pellets were added to 500
A catalyst J was prepared in the same manner as the preparation of the catalyst D except that it was calcined at 1 ° C. for 1 hour.

Preparation of catalyst K Preparation of catalyst D except that an aqueous solution of ruthenium chloride (0.5% by weight of ruthenium with respect to zirconia) and cobalt nitrate (1.0% by weight of cobalt with respect to zirconia) was used during impregnation. Similarly, a catalyst K was prepared.

Preparation of catalyst L Preparation of catalyst D except that an aqueous solution of ruthenium chloride (0.5% by weight of ruthenium with respect to zirconia) and manganese nitrate (1.0% by weight of manganese with respect to zirconia) was used during impregnation. Similarly, a catalyst L was prepared.

Preparation of catalyst M Ruthenium chloride (0.5% by weight as ruthenium against zirconia), cobalt nitrate (1.0% by weight as zirconia as cobalt) and barium nitrate (2.0% by weight as zirconia as barium) were dissolved during impregnation. A catalyst M was prepared in the same manner as the preparation of the catalyst D except that the above aqueous solution was used.

Preparation of Catalyst N Ruthenium chloride (0.5% by weight of ruthenium to zirconia), manganese nitrate (1.0% of manganese to zirconia) and potassium nitrate (0.5% of potassium to zirconia) were dissolved during impregnation. A catalyst N was prepared in the same manner as the preparation of the catalyst D except that an aqueous solution was used.

Measurement of the pore characteristics of the catalyst carrier The pore distribution of the carrier (catalyst carrier) in the various catalysts prepared above was measured by the mercury porosimetry method to obtain a pore size of 30 to 3.5x10.
^It was measured in the range of ⁵ Å. In addition, this measurement was performed using Shimadzu Micromeritics Autopore 9220 as an apparatus, and the measurement pressure was in the range of 14 to 60,000 psi.

The pore characteristics of each catalyst carrier were obtained from the obtained pore distribution. The results are summarized in Table 1.

As described above, the pore volume values in these results include those having a pore diameter of less than 30Å and a pore diameter of 3.
It should be noted that pores larger than 5x10 ⁵ Å are not included.

Example of Hydrocarbon Steam Reforming Reaction Each of the catalysts prepared above was molded into 16 to 32 mesh granules, 6 ml was filled in a quartz reaction tube having an inner diameter of 18 mm, and the reaction tube was loaded into a heating furnace.

While heating the quartz reaction tube to 600 ° C with a heating furnace, hydrogen gas was added to the catalyst layer at a space velocity (SV) of 2,000 hr ^{-1 in} the catalyst layer.
The catalyst was reduced by circulating it for a period of time. After that, the temperature of the heating furnace was raised to 800 ° C, and at this temperature, the steam / carbon ratio (S / C) was 4, and the space velocity (SV) was 12,000h.
Naphtha and steam were circulated through the catalyst layer under conditions of r ⁻¹ and reaction pressure of atmospheric pressure to carry out a steam reforming reaction of hydrocarbons.

The composition formula of the naphtha used is C _5.5 H ₁₃ on average,
The sulfur content was less than 0.1 ppm.

After reacting for 8 hours, the reaction conditions were S / C = 2, SV =
The reaction time was changed to 9,000 hr ^-1 and the reaction was continued for 2 hours.

Then, the supply of naphtha and steam was stopped, nitrogen was circulated, and the state was maintained for 1 hour.

In this way, the reaction and the holding operation with nitrogen were repeated several times, and an index relating to the catalyst activity and the deterioration rate was obtained from the temperature distribution of the endothermic portion in the reaction region and its change.

Table 1 shows the relative activity and relative deterioration rate of each catalyst based on catalyst D.

(Evaluation) As shown in Table 1, the carriers in the catalysts of Examples 1 to 9 had pore distributions (pore characteristics) within the scope of the present invention.
Have.

As shown in Table 1, it is clear that the catalyst of the present invention using the carrier having the pore distribution (pore characteristics) shown in the claims has high activity and small deterioration.

[Advantages of the Invention] According to the present invention, by using a carrier having a specific pore structure as a catalyst carrier, the steam reforming of hydrocarbon has excellent advantages such as high catalytic activity and long catalyst life. A catalyst for use can be provided.

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Claims (5)

[Claims] 1. The volume of pores having a pore diameter of 500Å or less is 0.15 ml / g.
The volume of pores with a pore diameter of 500Å or more is 0.14 ml / g
A catalyst for steam reforming of hydrocarbons, characterized in that a platinum group metal is supported on a carrier having the following range and an average pore size of 90 Å or more. 2. The hydrocarbon steam reforming catalyst according to claim 1, wherein the carrier is a zirconia-based carrier. 3. The catalyst for steam reforming of hydrocarbon according to claim 1, wherein the platinum group metal is Ru. 4. The catalyst for steam reforming of hydrocarbon according to claim 1, wherein the carrier carries cobalt and / or manganese. 5. The catalyst for steam reforming of hydrocarbon according to claim 1, wherein the carrier carries cobalt and / or manganese, and potassium and / or barium.