WO2017213093A1

WO2017213093A1 - Magnesia-based catalyst carrier, and production method therefor

Info

Publication number: WO2017213093A1
Application number: PCT/JP2017/020844
Authority: WO
Inventors: 冬樹八木; 篤郎南雲; 隆一金井
Original assignee: 千代田化工建設株式会社
Priority date: 2016-06-10
Filing date: 2017-06-05
Publication date: 2017-12-14
Also published as: JP2017217630A; TW201811429A

Abstract

Provided is a catalyst carrier which is capable of inhibiting carbon deposition on a catalyst when used in a gas-phase organic reaction, and with which the gas-phase organic reaction can be performed efficiently and stably over a long period of time. This magnesia-based catalyst carrier includes calcium oxide which is present in the vicinity of the surfaces of magnesium oxide particles. The calcium oxide content is 0.005-1.5 mass% in terms of Ca with respect to the total amount of the magnesium oxide particles.

Description

Magnesia catalyst carrier and method for producing the same

The present invention relates to a magnesia (magnesium oxide) -based catalyst carrier, and more specifically to a catalyst carrier having a form in which calcia (calcium oxide) is deposited in the vicinity of the surface of magnesia particles. The magnesia-based catalyst carrier of the present invention is a catalyst used for gas phase organic reactions, particularly for reactions that may cause carbon deposition on the catalyst, such as production of synthesis gas by reforming (reforming) natural gas. It can be preferably used as a carrier.

Synthesis gas mainly composed of carbon monoxide and hydrogen is widely used as a raw material for dimethyl ether, methanol, Fischer-Tropsch oil, acetic acid, diphenylmethane diisocyanate, methyl methacrylate and the like. Such synthesis gas includes, for example, carbon dioxide reforming in which natural gas (mainly composed of light hydrocarbons represented by methane) and carbon dioxide are reacted in the presence of a catalyst, natural gas and steam (water vapor) ) In the presence of a catalyst, or carbon dioxide / steam reforming in which natural gas is reacted with carbon dioxide and steam in the presence of a catalyst.

At this time, carbon dioxide reforming or carbon dioxide / steam reforming has a problem that carbon is likely to be deposited on the catalyst due to a reaction between a light hydrocarbon as a raw material and carbon monoxide as a product. When carbon is deposited on the catalyst, the catalytic activity is impaired and the reaction efficiency is lowered. Therefore, it is difficult to stably and efficiently produce synthesis gas for a long period of time. Carbon deposition also causes an increase in the differential pressure and blockage of the reforming reactor.

For the problem that carbon is deposited on the catalyst, for example, a carbon dioxide reforming catalyst in which a ruthenium compound is supported on a support made of aluminum oxide and at least one compound of alkaline earth metal oxides. (Refer to Patent Document 1), carbon dioxide in which rhodium is supported on a carrier made of a metal oxide or lanthanoid metal oxide of Group 2 to Group 4 or a composite of alumina containing those metal oxides A reforming catalyst (see Patent Document 2) or a carrier made of a metal oxide supports at least one catalyst metal selected from rhodium, ruthenium, iridium, palladium and platinum, and has a specific surface area of 25 m ² / g or less. The metal ion in the carrier metal oxide has an electronegativity of 13.0 or less, and the supported amount of the catalyst metal is a metal equivalent amount. 0.0005 to 0.1 mol% synthesis gas production catalyst (see Patent Document 3) are known to oxide.

On the other hand, in carbon dioxide / steam reforming of natural gas (methane), the amount ratio (volume ratio) of the raw material gas to the synthetic gas produced is shown in FIG. 1 depending on the molar ratio of carbon dioxide in the raw material gas or steam and methane. As shown, the reforming is performed by adjusting the molar ratio of carbon dioxide / steam to methane in the source gas so that the volume ratio (volume ratio) of the source gas to the synthesis gas to be generated becomes small. Is desirable from the viewpoint of synthesis efficiency. However, when reforming is performed at a molar ratio of carbon dioxide / steam and methane in such a raw material gas, there is a problem that carbon deposition is very likely to occur on the catalyst surface.

As mentioned above, the problem of carbon deposition on the catalyst often becomes an obstacle when trying to carry out a gas phase organic reaction under efficient conditions, which is carbon dioxide reforming or carbon dioxide. / It is not a problem limited to steam reforming. That is, if there is a catalyst carrier that is difficult to deposit carbon, the possibility of efficiently performing many gas phase organic reactions greatly increases.

JP-A-6-279003 JP-A-9-168740 Japanese Patent No. 3345782

The present invention is based on the viewpoint described above, in a gas phase organic reaction, particularly in a reaction that easily causes carbon deposition by including decomposition and modification of hydrocarbon such as carbon dioxide reforming of natural gas (methane) An object of the present invention is to provide a catalyst carrier that hardly deposits carbon on the catalyst to be used.

As a result of intensive studies, the inventors of the present invention contain magnesium oxide particles and calcium oxide present in the vicinity of the surface, and the content of the calcium oxide with respect to the entire particles is 0.005% by mass or more in terms of Ca. It has been found that the above object can be achieved by providing a magnesia-based catalyst carrier of 1.5% by mass, and thus the present invention has been completed.

The calcium oxide content per unit surface area of the magnesium oxide particles is preferably 0.05 mg-Ca / m ² to 150 mg-Ca / m ² in terms of Ca.

It is preferable that the vicinity of the surface of the magnesium oxide particles is a region whose depth from the surface is within 10% of the maximum depth of each particle.

It is preferable that the vicinity of the surface of the magnesium oxide particles forms a calcium oxide-containing layer.

The method for producing a magnesia-based catalyst carrier of the present invention includes a step of firing raw material magnesium oxide particles containing calcium oxide at 1000 ° C. or more, thereby aggregating or fusing the raw material magnesium oxide particles to form magnesium oxide particles. In addition, calcium oxide is precipitated in the vicinity of the surface of the magnesium oxide particles, calcium oxide is contained in the vicinity of the surface of the magnesium oxide particles, and the content of the calcium oxide with respect to the entire particles is 0.005% by mass in terms of Ca. It is characterized by obtaining a catalyst carrier of ˜1.5% by mass.

In the above method, it is preferable to calcinate after adding carbon in the range of 1% by mass to 5% by mass with respect to the raw material magnesium oxide particles.

In the above method, the catalyst carrier preferably has a calcium oxide content per unit surface area of the magnesium oxide particles of 0.05 mg-Ca / m ² to 150 mg-Ca / m ² in terms of Ca.

In the above method, it is preferable that the catalyst carrier has a region in the vicinity of the surface of the magnesium oxide particles that is within 10% of the maximum depth of each particle from the surface.

In the method, it is preferable that the vicinity of the surface of the magnesium oxide particles forms a calcium oxide-containing layer.

When the magnesia-based catalyst carrier of the present invention is used, carbon deposition on the catalyst can be remarkably suppressed, so that a gas phase organic reaction that may cause carbon deposition can be stably and efficiently performed for a long period of time. it can.

It is a figure which shows the relationship between the abundance ratio (molar ratio) of a carbon dioxide or a steam and carbon in carbon dioxide / steam reforming, and the ratio (volume ratio) of a synthesis gas to produce | generate. It is a figure which shows typically the example of the cross-sectional shape of the magnesium oxide particle which comprises the catalyst support | carrier of this invention. It is a figure which shows typically a mode that calcium oxide exists in the surface vicinity of the magnesium oxide particle which comprises the catalyst support | carrier of this invention. 3 is a result of EPMA analysis of a carrier for a synthesis gas production catalyst of Example 1. FIG. 2 is an EPMA analysis result of the synthesis gas production catalyst of Example 1. FIG. It is the result of element mapping by EDX of the synthesis gas production catalyst after the reduction treatment of Example 1. 4 is an EPMA analysis result of a synthesis gas production catalyst of Comparative Example 1.

The magnesia-based catalyst carrier of the present invention contains calcium oxide in the vicinity of the surface of the magnesium oxide particles, and the content of the calcium oxide with respect to the whole particles is 0.005% by mass to 1.5% by mass in terms of Ca. .

The form of the magnesium oxide particles constituting the magnesia-based catalyst carrier of the present invention is not particularly limited, and each particle constituting the raw material magnesium oxide may be present alone, or a plurality of particles May be agglomerated. In FIG. 2, the example of the cross-sectional shape of the magnesium oxide particle which comprises the catalyst support | carrier of this invention is shown typically. As shown in FIG. 2, the shape of the magnesium oxide particles is a spherical shape (FIG. 2A) formed by agglomerating a plurality of particles constituting the raw material magnesium oxide and melting each other, and the raw material magnesium oxide. A peanut shape formed by agglomeration and fusion of the two particles constituting the nuclei and having both ends 52 having a larger diameter than the central portion 51 (FIG. 2 (b)), raw material magnesium oxide The shape (FIG. 2 (c)) in which the three particles constituting the material are aggregated and fused. The catalyst carrier of the present invention must be magnesia-based, that is, formed of particles mainly composed of magnesium oxide, and other metals such as zirconium oxide (ZnO) and alumina (Al ₂ O ₃ ). If the main component is an oxide, the effect of the present application cannot be obtained.

The catalyst carrier of the present invention contains calcium oxide (CaO) in the vicinity of the surface of the magnesium oxide (MgO) particles, but the presence form of calcium oxide may be various. For example, the whole or part of the region near the surface of the magnesium oxide particles may form a calcium oxide-containing layer. Note that the calcium oxide-containing layer formed in the vicinity of the surface of the magnesium oxide particles in this way may contain magnesium oxide, or the layer made of only calcium oxide may cover the surface of the magnesium oxide particles. Good. Further, calcium oxide may be locally unevenly distributed on the surface of the magnesium oxide particles. For example, calcium oxide may be locally present in the recesses on the surface of the magnesium oxide particles. FIG. 3 schematically shows an example of a form in which calcium oxide is present on the surface of magnesium oxide particles in the catalyst carrier of the present invention. As shown in FIG. 3, the catalyst carrier 10 has a calcium oxide-containing layer 12 formed on the entire surface of the magnesium oxide particles 11 (FIG. 3A) or a portion of the surface of the magnesium oxide particles 11. The inclusion layer 13 may be formed (FIG. 3B), and calcium oxide may be locally present in the recesses on the surface of the magnesium oxide particles.

The catalyst carrier of the present invention thus contains calcium oxide in the vicinity of the surface of the magnesium oxide particles. The content of calcium oxide present in the vicinity of the surface of the magnesium oxide particles is 0.005% to 1.5% by mass, particularly 0.3% to 1.4% by mass in terms of Ca. It is. By adopting such a configuration, it is possible to remarkably suppress carbon deposition during a gas phase organic reaction that may be accompanied by carbon deposition such as carbon dioxide reforming or carbon dioxide / steam reforming. A desired gas phase organic reaction can be carried out stably and efficiently over a period of time. When the content of calcium oxide present in the vicinity of the surface of the magnesium oxide particles is less than 0.005% by mass in terms of Ca, carbon deposition tends to occur on the catalyst surface, which is less than 1.5% by mass. When the amount is large, the catalytic activity is lowered and the effect of the present invention cannot be obtained.

The content of calcium oxide present in the vicinity of the surface of the magnesium oxide particles in terms of Ca with respect to the entire particles is determined by the following method. That is, the total Ca amount in terms of Ca present in the magnesium oxide particles may be obtained by dissolving the sample (catalyst support) with aqua regia and using an ICP emission spectrometer. At this time, the distribution of Ca present in the magnesium oxide particles is analyzed by EPMA (electron probe microanalysis), Ca is not present inside the magnesium oxide particles, and almost all of Ca is present near the surface of the magnesium oxide particles. By confirming this by EPMA analysis, the Ca amount determined by the ICP emission analysis can be obtained as the Ca equivalent content of calcium oxide present in the vicinity of the surface of the magnesium oxide particles.

In the catalyst carrier of the present invention, the calcium oxide content per unit surface area of the magnesium oxide particles is preferably 0.05 mg-Ca / m ² to 150 mg-Ca / m ² in terms of Ca. The Ca equivalent content (mg-Ca / m ² ) of calcium oxide per unit surface area of magnesium oxide particles is the Ca equivalent content of calcium oxide present in the vicinity of the surface per 1 g of magnesium oxide particles (unit: mg). It is determined by dividing −Ca) by the specific surface area (unit: m ² / g) of the magnesium oxide particles (catalyst support).

Calcium oxide is present in a region where the depth from the surface of the magnesium oxide particle is within 10% of the maximum depth of each particle, that is, “near the surface” where calcium oxide is present is 10 of the maximum depth of each particle. % Is preferable. At this time, “the region where the depth from the surface is within 10% of the maximum depth of each particle” means that any point in the region of each particle is within 10% of the maximum depth of the particle. means. More precisely, the distance between the centroid of each particle and the surface farthest from the centroid is called the maximum depth of the particle, and when this is the radius r ₁ , an arbitrary point in the region is located from the surface of the catalyst support. , which means that it is not far from the distance of r _1/10 towards the center of gravity.

The size of the magnesium oxide particles constituting the catalyst carrier of the present invention is, for example, a maximum diameter of 0.1 to 10 μm, but is not limited thereto. The thickness of the calcium oxide-containing layer is, for example, 5 to 70 nm.

The shape of the catalyst carrier of the present invention is, for example, a ring shape, a multi-hole shape, a tablet shape, or a pellet shape.

The magnesia-based catalyst carrier of the present invention, for example, by calcining raw magnesium oxide particles containing calcium oxide at 1000 ° C. or more to aggregate the raw magnesium oxide particles to form magnesium oxide particles, and It can be produced by depositing calcium oxide in the vicinity of the surface of the magnesium particles.

That is, in the method for producing a catalyst carrier of the present invention, raw material magnesium oxide particles containing calcium oxide are used. The calcium oxide content contained in the raw material magnesium oxide particles is 0.005% to 1.5% by mass, particularly 0.3% to 1.4% by mass. The “raw material magnesium oxide particles containing calcium oxide” as used herein means that the raw material magnesium oxide particles used as the raw material contain, for example, calcium oxide uniformly within a range of 0.005 mass% to 1.5 mass%. . Accordingly, high-purity magnesium oxide such as commercially available magnesium oxide that has been conventionally used has a low calcium oxide content and cannot be used as raw material magnesium oxide particles in the present invention.

The raw material magnesium oxide particles containing calcium oxide are formed into a desired catalyst carrier shape, for example, a ring shape, a multi-hole shape, a tablet shape, and a pellet shape, as necessary.

¡When forming, a lubricant such as carbon may be added. For example, it is preferable to add carbon in the range of 1% by mass to 5% by mass with respect to the raw material magnesium oxide particles.

The raw material magnesium oxide particles containing calcium oxide formed as necessary are fired at 1000 ° C. or higher to aggregate the raw magnesium oxide particles to form magnesium oxide particles, and the surface of the magnesium oxide particles has calcium oxide. By precipitating the catalyst, the catalyst carrier of the present invention can be produced.

When the raw material magnesium oxide particles are fired under specific conditions described later in detail, the raw material magnesium oxide particles aggregate to form magnesium oxide particles. In addition, the calcium oxide present inside the raw material magnesium oxide particles exudes to the surface by firing under the specific conditions, so that the calcium oxide is precipitated near the surface of the magnesium oxide particles and oxidized near the surface of the magnesium oxide particles. A calcium-containing layer is formed, or the calcium-containing layer is locally present in the recesses on the surface of the magnesium oxide particles.

When the amount of calcium oxide contained in the raw material magnesium oxide particles is small, the amount of calcium oxide deposited in the vicinity of the surface becomes insufficient, and the effect of remarkably suppressing the carbon deposition of the present invention cannot be obtained.

Also, the firing temperature needs to be 1000 ° C. or higher. When the firing temperature is low, calcium oxide present in the raw material magnesium oxide particles does not precipitate near the surface of the magnesium oxide particles, and the effect of the present invention cannot be obtained. The firing temperature is preferably 1400 ° C. or lower.

The catalyst carrier of the present invention can also be produced by a method other than the above. Specifically, high-purity magnesium oxide (for example, MgO having a CaO content of 0.01 mass% or less and a purity of 99.9 mass% or more in terms of Ca) is stirred while boiling at 60 to 80 ° C. At the same time as obtaining Mg (OH) ₂ , Ca-added Mg (OH) ₂ particles are obtained by simultaneously dropping and stirring an aqueous solution of Ca (OH) ₂ . The Ca-added Mg (OH) ₂ particles thus obtained contain CaO almost uniformly inside. Then, the obtained Ca-added Mg (OH) ₂ particles are calcined at 1000 ° C. or higher, preferably 1400 ° C. or lower, with a lubricant added or molded as necessary, as in the above production method. Thus, the Ca-added Mg (OH) ₂ particles are aggregated to form magnesium oxide particles, and calcium oxide is precipitated in the vicinity of the surface of the magnesium oxide particles, whereby the catalyst carrier of the present invention can be produced.

In any of the production methods, basically, the operation of adding calcium oxide is not performed.

Here, the raw material magnesium oxide particles, the Ca-added Mg (OH) ₂ particles and the conditions for firing the molded body thereof, specifically, the calcium oxide content of the raw material magnesium oxide particles and Ca-added Mg (OH) ₂ particles In addition to the amount and firing temperature, depending on the firing atmosphere, firing time, type and amount of additives such as lubricant, size and shape of the compact to be fired, raw material magnesium oxide particles and Ca-added Mg (OH) Agglomeration of the _two particles, presence or absence of calcium oxide in the vicinity of the surface of the magnesium oxide particles, and the timing and degree change. Therefore, in order to form magnesium oxide particles by aggregating raw material magnesium oxide particles and Ca-added Mg (OH) ₂ particles and depositing calcium oxide near the surface of the magnesium oxide particles to form a calcium oxide-containing layer It is necessary to adjust the balance of these firing conditions.

For example, in order to produce a synthesis gas production catalyst using the catalyst carrier of the present invention, at least one of ruthenium (Ru) and rhodium (Rh) may be supported on the catalyst carrier of the present invention. In order to produce a synthesis gas production catalyst, Ru or Rh may be supported. However, the catalyst metal to be supported may be appropriately selected from other metals such as Ni, Ir, and Os depending on the reaction carried out using the catalyst. Well, if the catalyst thus produced is used, carbon deposition can be effectively suppressed in the reaction.

The amount of catalyst metal supported is usually 200 ppm to 2000 ppm in terms of metal with respect to the catalyst carrier of the present invention, but may be appropriately adjusted according to the reaction to be carried out. The amount of catalyst metal supported can generally be determined with an ICP emission spectrometer. Specifically, after a catalyst sample is dissolved in aqua regia, it can be quantified by irradiation with a predetermined measurement wavelength.

The specific surface area of the catalyst carrier of the present invention ^is preferably a 0.1m ² /g~1.0m 2 / g. Here, the “specific surface area” is a BET specific surface area calculated from the amount of nitrogen gas adsorbed using the BET adsorption isotherm. For example, a specific surface area measuring device (product name “AUTOSORB-1”, Yuasa Ionics) It is a value measured by a multipoint method using liquid nitrogen.

The catalyst metal supported on the catalyst support of the present invention has a depth from the surface of the catalyst support of the present invention within 10% of the particle diameter of the magnesium oxide particles (here, “depth to the center”). Preferably it is present. In other words, the region supporting the catalyst metal is preferably a region where the catalyst carrier of the present invention contains calcium oxide, that is, the vicinity of the surface of the magnesium oxide particles.

The form of the catalyst metal supported on the catalyst carrier of the present invention is not particularly limited, but it is preferably present adjacent to the calcium oxide in the vicinity of the surface of the magnesium oxide particles. The catalyst metal may cover all or part of the surface of the magnesium oxide particles, or the catalyst metal particles may be dispersed on the surface of the magnesium oxide particles. Or the catalyst metal may be unevenly distributed locally on the surface of the magnesium oxide particle, for example, may exist in the recessed part of the surface of the magnesium oxide particle. Further, the layered or particulate catalyst metal may be covered by at least a part of the calcium oxide layer, or the layered or particulate catalyst metal and the layered or particulate calcium oxide are alternately adjacent to each other. May be.

As a method for supporting the catalyst metal on the catalyst carrier of the present invention, an aqueous solution of the catalyst metal may be sprayed on the catalyst carrier of the present invention. An aqueous solution of a catalytic metal can be obtained by dissolving an inorganic acid salt such as nitrate or chloride of the metal or an organic acid salt such as acetate in water. The amount of the aqueous solution to be sprayed is preferably 1.0 to 1.3 times the amount of water absorbed by the catalyst carrier, for example. The water absorption amount of the catalyst carrier can be determined by the incipient-wetness method. This is a method in which pure water is dripped little by little with a micropipette or burette onto the catalyst carrier, and the amount of dripping until the catalyst surface gets wet is measured.

As another method, an impregnation method in which a metal salt to be supported or an aqueous solution thereof is added to and mixed with a dispersion in which the catalyst carrier of the present invention is dispersed in water may be employed.

A desired catalyst can be obtained by drying and calcining the catalyst carrier of the present invention on which a catalyst metal is supported. The conditions for drying and firing are not particularly limited. For example, the drying temperature is 50 to 150 ° C., the drying time is 1 to 3 hours, the firing temperature is 300 to 500 ° C., and the firing time is about 1 to 5 hours.

Hereinafter, examples will be described for further understanding of the present invention. Many of the following examples are examples in the case where the catalyst carrier of the present invention is produced and a synthesis gas production catalyst is produced using the catalyst carrier, but the use of the catalyst carrier of the present invention is limited to the synthesis gas production catalyst. However, the following examples do not limit the present invention. In the following, “wt%” and “wt ppm” are used as units representing the concentration and content of components, etc., but the values expressed in these units are expressed as “mass%” and “mass ppm”. Is the same as

<Example 1>
A powder of 98.7 wt% magnesium oxide (MgO) containing 0.3 wt% of calcium oxide (CaO) in terms of Ca inside (raw material magnesium oxide particles), and 3.0 wt% of MgO powder as a lubricant. % Carbon was mixed to form a 1/4 inch diameter cylindrical pellet. The formed pellets were calcined in air at 1180 ° C. for 3 hours (hours) to obtain a catalyst carrier. The obtained catalyst carrier had a BET specific surface area of 0.10 m ² / g.

When the obtained catalyst support was analyzed by ICP emission analysis (hereinafter also simply referred to as “ICP”), the catalyst support contained 0.3 wt% of CaO in terms of Ca. From the EPMA analysis results, it was confirmed that Ca was not present inside the catalyst support and Ca was present only in the vicinity of the surface of the MgO particles. Further, the MgO particles constituting the obtained catalyst carrier were significantly larger than the raw material magnesium oxide particles. Therefore, it is considered that the raw material MgO particles aggregate to form MgO particles, and CaO contained in the raw material MgO particles is precipitated in the vicinity of the MgO particle surface. The EPMA analysis result of the cross section of the catalyst carrier is shown in FIG. In addition, Table 1 shows quantitative results in terms of mol% of each element by EPMA analysis of the obtained catalyst carrier. The analysis points P1 to P10 are points indicated by arrows in FIG.

As shown in FIG. 4, the obtained catalyst carrier was composed of spherical or peanut-like particles. Each catalyst carrier particle was partially covered with a layer containing CaO (CaO-containing layer), and CaO was present in the recesses (dents) on the surface of the MgO particles. Moreover, these CaO existed in the area | region which is within 10% of the depth from the surface of a catalyst support | carrier (MgO particle | grain). When the calcium oxide content per unit surface area of the MgO particles was determined, it was 30 mg-Ca / m ² in terms of Ca. Further, as shown in FIG. 4 and Table 1, the central part (analysis points P1 and P9) of the peanut-like particles contains a very small amount of Ca, and most of Ca is present at both ends (analysis points P2 to P8 and P10). It was included.

Next, 0.15 cc (1.0 times the amount of water absorbed by the catalyst carrier) is sprayed onto the obtained catalyst carrier with an aqueous solution of nitrosylruthenium nitrate containing 0.5 wt% Ru against 1.0 g of the catalyst carrier. Ru was supported on the carrier. The Ru-supported catalyst support thus obtained was dried in an oven at 120 ° C. for 2.5 hours in the air, and then calcined in the electric furnace at 400 ° C. for 2.0 hours in the air to obtain a catalyst.

The obtained catalyst contained Ru at a ratio of 750 wtppm with respect to the catalyst, and its BET specific surface area was 0.10 m ² / g. Further, EPMA analysis was performed on the obtained catalyst in the same manner as the catalyst carrier. The EPMA analysis result of the catalyst is shown in FIG. In addition, Table 2 shows quantitative results in terms of mol% of each element by EPMA analysis of the obtained catalyst. The analysis points P1 to P11 are points indicated by arrows in FIG.

As shown in FIG. 5, in the obtained catalyst, Ru was present in a region close to the surface of the catalyst particles, that is, a region within 10% of the depth from the catalyst surface. Since the positions of Ru and Ca overlap, it can be said that CaO exists in the vicinity of the Ru. Note that Ru and CaO contained in the catalyst carrier were all present in the vicinity of the surface of the MgO particles. Further, as shown in FIG. 5 and Table 2, the central part (analysis points P3 and P10) of the peanut-like particles contains a very small amount of Ca, and most of Ca is at both end parts (analysis points P1 to P2, P4 to P4). P9 and P11).

<Reaction Example 1>
50 cc of the catalyst prepared in Example 1 was filled in the catalyst layer of the reactor, and a methane H ₂ O / CO ₂ reforming test was performed. The reactor has a configuration in which a raw material gas is introduced from above the catalyst layer, and the raw material gas introduced into the catalyst layer descends and passes through the catalyst layer.

Specifically, first, a mixed gas in which the molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/0) is preliminarily passed through the catalyst layer at 500 ° C. for 1 hour to be brought into contact with the catalyst. Thus, reduction treatment (activation of the catalyst) was performed. Thereafter, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1: 2.5: 1.5 is used, the gas pressure at the catalyst layer outlet is 1471 kPaG, the gas temperature at the catalyst layer outlet is 850 ° C., methane standard The treatment was performed under the condition of GHSV = 2500 / hour.

As a result, the CH ₄ conversion after 5 hours from the start of the reaction was 92.5% (equilibrium conversion of CH ₄ under the experimental conditions = 92.5%), and after 1500 hours from the start of the reaction. The conversion rate of CH ₄ was 92.5%. Further, after 1500 hours, when the catalyst was extracted by dividing it into four equal parts in the vertical direction, carbon was deposited on the catalyst, and the carbon / catalyst was 0.2 wt% (Top), 0. They were 15 wt% (Md1), 0.1 wt% (Md2), and 0.10 wt% (Btm). The conversion rate of CH ₄ is defined by the following formula.
CH ₄ conversion (%) = (AB) / A × 100
A: raw material CH ₄ moles of gas B: CH ₄ moles in the product (gas discharged from the catalyst layer)

In addition, S-TEM analysis of the catalyst (catalyst before aeration of raw material gas) treated under the reduction treatment conditions described in Reaction Example 1 was performed. The result of element mapping by EDX is shown in FIG. In FIG. 6, Ca, Mg, Ru, and the lower stage are TEM photographs in order from the left side of the upper stage.

As a result, it was confirmed that particulate Ru was present on the catalyst surface. Moreover, as shown in FIG. 6, it was confirmed that Ru exists in the Ca vicinity.

<Example 2>
Inside, MgO powder containing 0.3 wt% CaO in terms of Ca and having a purity of 98.7 wt% or more is mixed with 3.0 wt% carbon as a lubricant to MgO powder, and the diameter is 1/4 inch. A cylindrical pellet was formed. The formed pellets were calcined in air at 1180 ° C. for 3 hours to obtain a catalyst carrier. The obtained catalyst carrier had a BET specific surface area of 0.10 m ² / g.

The obtained catalyst carrier was analyzed by ICP as in Example 1. As a result, the catalyst carrier contained 0.3 wt% of CaO in terms of Ca. From the EPMA analysis results, it was confirmed that Ca was not present inside the catalyst support and Ca was present only in the vicinity of the surface of the MgO particles. Further, the MgO particles constituting the obtained catalyst carrier were significantly larger than the raw material magnesium oxide particles. Therefore, it is considered that the raw material MgO particles aggregate to form MgO particles, and CaO contained in the raw material MgO particles is precipitated in the vicinity of the MgO particle surface.

The obtained catalyst carrier is in the form of particles, as in Example 1. Part of the surface of the MgO particles is covered with a layer containing CaO, and CaO is present in the recesses on the surface of the MgO particles. It was. Moreover, these CaO existed in the area | region which is within 10% of the depth from the surface of a catalyst support | carrier. The amount of CaO present per unit surface area of the MgO particles was determined to be 30 mg-Ca / m ² in terms of Ca. Moreover, the center part of peanut-like particle | grains contained only trace amount Ca, and most Ca was contained in both ends.

Next, an aqueous ruthenium chloride hydrate (RuCl ₃ ) solution containing 0.55 wt% of Ru was added to the obtained catalyst support in an amount of 0.17 cc (1.1% of the amount of water absorbed by the catalyst support). The catalyst support was loaded with Ru. The Ru-supported catalyst support thus obtained was dried in an oven at 120 ° C. for 2.5 hours in the air, and then calcined in the electric furnace at 400 ° C. for 2.0 hours in the air to obtain a catalyst.

The obtained catalyst contained Ru in a proportion of 900 wtppm with respect to the catalyst, and its BET specific surface area was 0.10 m ² / g. Further, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ru was present in the vicinity of the surface of the catalyst particles, that is, in a region within 10% of the depth from the catalyst surface. Therefore, it can be said that CaO exists in the vicinity of the Ru.

<Reaction example 2>
50 cc of the catalyst prepared in Example 2 was charged into the same reactor as that used in Example 1, and a CO ₂ reforming test of methane was performed.

Specifically, first, the catalyst is prepared by passing a mixed gas of H ₂ and H ₂ O in a molar ratio (H ₂ / H ₂ O = 1/3) in advance through the catalyst layer at 500 ° C. for 1 hour. The reduction process was performed by making it contact. Thereafter, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1: 1: 0 is prepared by using a gas pressure of 1960 kPaG at the outlet of the catalyst layer, a gas temperature of 850 ° C. at the outlet of the catalyst layer, and GHSV of methane reference = 2. The treatment was performed at 500 / hour.

As a result, the CH ₄ conversion rate after 5 hours from the start of the reaction was 54.8% (equilibrium conversion rate of CH ₄ under experimental conditions = 54.8%), and 300 hours after the start of the reaction. The conversion rate of CH ₄ was 54.8%, and the conversion rate of CH ₄ after 1100 hours was 53.1%. Further, after 1100 hours, the amounts of carbon on the catalyst extracted by dividing into 4 parts as in Example 1 were 0.25 wt%, 0.1 wt%, 0.1 wt%, and 0.04 wt% in order from the top. It was. Similarly to Example 1, the catalyst treated under the pretreatment conditions described in Reaction Example 2 was analyzed, and it was confirmed that particulate Ru was present on the catalyst surface.

<Example 3>
Inside, MgO powder containing 0.3 wt% CaO in terms of Ca and having a purity of 98.7 wt% or more is mixed with 3.0 wt% carbon as a lubricant to MgO powder, and the diameter is 1/4 inch. A cylindrical pellet was formed. The formed pellets were calcined in air at 1180 ° C. for 3 hours to obtain a catalyst carrier. The obtained catalyst carrier had a BET specific surface area of 0.10 m ² / g.

Next, an aqueous ruthenium nitrate solution containing 0.17 wt% Ru is sprayed onto the obtained catalyst carrier at 0.18 cc (1.2 times the water absorption amount of the catalyst carrier) with respect to 1.0 g of the catalyst carrier, Ru was supported on the catalyst support. The Ru-supported catalyst support thus obtained was dried in an oven at 120 ° C. for 2.5 hours in the air, and then calcined in the electric furnace at 400 ° C. for 2.0 hours in the air to obtain a catalyst.

The obtained catalyst contained Ru in a proportion of 300 wtppm with respect to the catalyst, and its BET specific surface area was 0.10 m ² / g. Further, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ru was present in the vicinity of the surface of the catalyst particles, that is, in a region within 10% of the depth from the catalyst surface. Therefore, it can be said that CaO exists in the vicinity of the Ru.

<Reaction Example 3>
A reactor similar to that used in Example 1 was charged with 50 cc of the catalyst prepared in Example 3, and an H ₂ O / CO ₂ reforming test for methane was performed.

Specifically, first, the catalyst is prepared by passing a mixed gas of H ₂ and H ₂ O in a molar ratio (H ₂ / H ₂ O = 1/6) in advance through the catalyst layer at 500 ° C. for 1 hour. The reduction process was performed by making it contact. Thereafter, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1: 3: 0.3 is used, the gas pressure at the catalyst layer outlet is 1471 kPaG, the gas temperature at the catalyst layer outlet is 900 ° C., the methane reference GHSV = The treatment was performed at 2,500 / hour.

As a result, the CH ₄ conversion after 5 hours from the start of the reaction was 97.0% (equilibrium conversion of CH ₄ under experimental conditions = 97.0%), and 15,000 hours had elapsed from the start of the reaction. The subsequent conversion rate of CH ₄ was 97.0%. Further, after 15,000 hours had elapsed, the amount of carbon on the catalyst extracted in four portions in the same manner as in Example 1 was 0.2 wt%, 0.05 wt%, 0.03 wt%, and 0.02 wt% in order from the top. there were. Similarly to Example 1, when the catalyst treated under the pretreatment conditions described in Reaction Example 3 was analyzed, it was confirmed that particulate Ru was present on the catalyst surface.

<Example 4>
Inside, MgO powder containing 0.3 wt% CaO in terms of Ca and having a purity of 98.7 wt% or more is mixed with 3.0 wt% carbon as a lubricant to MgO powder, and the diameter is 1/4 inch. A cylindrical pellet was formed. The formed pellets were calcined in air at 1150 ° C. for 3 hours to obtain a catalyst carrier. The obtained catalyst carrier had a BET specific surface area of 0.12 m ² / g.

The obtained catalyst carrier is in the form of particles, as in Example 1. Part of the surface of the MgO particles is covered with a layer containing CaO, and CaO is present in the recesses on the surface of the MgO particles. It was. Moreover, these CaO existed in the area | region which is within 10% of the depth from the surface of a catalyst support | carrier. The amount of CaO present per unit surface area of the MgO particles was determined to be 25 mg-Ca / m ² in terms of Ca. Moreover, the center part of peanut-like particle | grains contained only trace amount Ca, and most Ca was contained in both ends.

Next, an aqueous solution of rhodium acetate (Rh (CH ₃ COO) ₃ ) containing 0.3 wt% Rh was added to the obtained catalyst carrier in an amount of 0.15 cc (1 of the water absorption amount of the catalyst carrier). (0.times.) And Rh was supported on the catalyst carrier. The catalyst carrier carrying Rh thus obtained was dried in an oven at 120 ° C. for 2.5 hours in air and then calcined in an electric furnace at 650 ° C. for 2.0 hours in air to obtain a catalyst.

The obtained catalyst contained Rh at a ratio of 450 wtppm with respect to the catalyst, and its BET specific surface area was 0.12 m ² / g. Further, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Rh was present in the vicinity of the surface of the catalyst particles, that is, in a region within 10% of the depth from the catalyst surface. Therefore, CaO was present in the vicinity of the Rh.

<Reaction Example 4>
The same reactor used in Example 1 was charged with 50 cc of the catalyst prepared in Example 4, and a CO ₂ reforming test for methane was performed.

Specifically, first, the catalyst is prepared by passing a mixed gas of H ₂ and H ₂ O in a molar ratio (H ₂ / H ₂ O = 1/0) in advance through the catalyst layer at 500 ° C. for 1 hour. The reduction process was performed by making it contact. Thereafter, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1: 1: 0 is prepared by using a gas pressure of 1960 kPaG at the outlet of the catalyst layer, a gas temperature of 850 ° C. at the outlet of the catalyst layer, and GHSV of methane reference = 2. The treatment was performed at 500 / hour.

As a result, the CH ₄ conversion rate after 5 hours from the start of the reaction was 54.8% (equilibrium conversion rate of CH ₄ under experimental conditions = 54.8%), and 300 hours after the start of the reaction. The conversion rate of CH ₄ was 54.8%, and the conversion rate of CH ₄ after 800 hours was 52.3%. Further, after 800 hours, the amount of carbon on the catalyst extracted in four portions in the same manner as in Example 1 was 0.15 wt%, 0.10 wt%, 0.05 wt%, and 0.03 wt% in order from the top. It was. Similarly to Example 1, when the catalyst treated under the pretreatment conditions described in Reaction Example 4 was analyzed, it was confirmed that particulate Rh was present on the catalyst surface.

<Example 5>
Inside, MgO powder containing 0.3 wt% CaO in terms of Ca and having a purity of 98.7 wt% or more is mixed with 3.0 wt% carbon as a lubricant to MgO powder, and the diameter is 1/4 inch. A cylindrical pellet was formed. The formed pellets were calcined in air at 1200 ° C. for 3 hours to obtain a catalyst carrier. The obtained catalyst carrier had a BET specific surface area of 0.08 m ² / g.

The obtained catalyst support was in the same particle form as in Example 1, a part of the surface of the MgO particles was covered with a layer containing CaO, and CaO was present in the recesses on the surface of the MgO particles. . Moreover, these CaO existed in the area | region which is within 10% of the depth from the surface of a catalyst support | carrier. The amount of CaO present per unit surface area of the MgO particles was determined to be 37.5 mg-Ca / m ² in terms of Ca. Moreover, the center part of peanut-like particle | grains contained only trace amount Ca, and most Ca was contained in both ends.

Next, an aqueous solution of nitrosylruthenium nitrate containing 0.85 wt% Ru is sprayed onto the obtained catalyst carrier at 0.13 cc (1.0 times the water absorption amount of the catalyst carrier) with respect to 1.0 g of the catalyst carrier, Ru was supported on the catalyst support. The Ru-supported catalyst support thus obtained was dried in an oven at 120 ° C. for 2.5 hours in the air, and then calcined in the electric furnace at 400 ° C. for 2.0 hours in the air to obtain a catalyst.

The obtained catalyst contained Ru at a rate of 1100 wtppm with respect to the catalyst, and its BET specific surface area was 0.08 m ² / g. Further, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ru was present in the vicinity of the surface of the catalyst particles, that is, in a region within 10% of the depth from the catalyst surface. Therefore, it can be said that CaO exists in the vicinity of the Ru.

<Reaction Example 5>
50 cc of the catalyst prepared in Example 5 was charged into a reactor similar to that used in Example 1, and a CO ₂ reforming test for methane was performed.

Specifically, first, the catalyst is prepared by passing a mixed gas of H ₂ and H ₂ O in a molar ratio (H ₂ / H ₂ O = 1/3) in advance through the catalyst layer at 500 ° C. for 1 hour. The reduction process was performed by making it contact. Thereafter, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1: 1: 0 is converted into a catalyst layer outlet gas pressure of 1960 kPaG, a catalyst layer outlet gas temperature of 880 ° C., methane-based GHSV = 2, The treatment was performed at 500 / hour.

As a result, the CH ₄ conversion rate after 5 hours from the start of the reaction was 54.8% (equilibrium conversion rate of CH ₄ under experimental conditions = 54.8%), and 300 hours after the start of the reaction. The conversion rate of CH ₄ was 54.8%, and the conversion rate of CH ₄ after 700 hours was 53.5%. Further, after 700 hours, the amounts of carbon on the catalyst extracted by dividing into 4 parts as in Example 1 were 0.15 wt%, 0.04 wt%, 0.03 wt%, and 0.01 wt%, respectively, from the top. It was. Further, as in Example 1, the catalyst treated under the pretreatment conditions described in Reaction Example 5 was analyzed, and it was confirmed that particulate Ru was present on the catalyst surface.

<Example 6>
Inside, MgO powder containing 0.3 wt% CaO in terms of Ca and having a purity of 98.7 wt% or more is mixed with 3.0 wt% carbon as a lubricant to MgO powder, and the diameter is 1/4 inch. A cylindrical pellet was formed. The formed pellets were calcined in air at 1130 ° C. for 3 hours to obtain a catalyst carrier. The obtained catalyst carrier had a BET specific surface area of 0.15 m ² / g.

The obtained catalyst carrier is in the form of particles, as in Example 1. Part of the surface of the MgO particles is covered with a layer containing CaO, and CaO is present in the recesses on the surface of the MgO particles. It was. Moreover, these CaO existed in the area | region which is within 10% of the depth from the surface of a catalyst support | carrier. The amount of CaO present per unit surface area of the MgO particles was determined to be 20 mg-Ca / m ² in terms of Ca. Moreover, the center part of peanut-like particle | grains contained only trace amount Ca, and most Ca was contained in both ends.

Next, an aqueous ruthenium nitrate solution containing 0.6 wt% Ru is sprayed on the obtained catalyst carrier at 0.18 cc (1.2 times the water absorption amount of the catalyst carrier) with respect to 1.0 g of the catalyst carrier, Ru was supported on the catalyst support. The Ru-supported catalyst support thus obtained was dried in an oven at 120 ° C. for 2.5 hours in the air, and then calcined in the electric furnace at 400 ° C. for 2.0 hours in the air to obtain a catalyst.

The obtained catalyst contained Ru at a ratio of 780 wtppm with respect to the catalyst, and its BET specific surface area was 0.15 m ² / g. Further, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ru was present in the vicinity of the surface of the catalyst particles, that is, in a region within 10% of the depth from the catalyst surface. Therefore, it can be said that CaO exists in the vicinity of the Ru.

<Reaction example 6>
A reactor similar to that used in Example 1 was charged with 50 cc of the catalyst prepared in Example 6, and an H ₂ O / CO ₂ reforming test for methane was performed.

Specifically, first, the catalyst is prepared by passing a mixed gas of H ₂ and H ₂ O in a molar ratio (H ₂ / H ₂ O = 1/2) in advance through the catalyst layer at 500 ° C. for 1 hour. The reduction treatment was carried out by contact. Thereafter, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1: 0.4: 1 is used, the gas pressure at the catalyst layer outlet is 1960 kPaG, the gas temperature at the catalyst layer outlet is 880 ° C., the methane reference GHSV = The treatment was performed at 2,500 / hour.

As a result, the CH ₄ conversion after 5 hours from the start of the reaction was 66.7% (equilibrium conversion of CH ₄ under the experimental conditions = 66.7%), and after 13,000 hours from the start of the reaction. The conversion rate of CH ₄ was 66.7%. Further, after 13000 hours had passed, the amount of carbon on the catalyst extracted in four portions in the same manner as in Example 1 was 0.11 wt%, 0.05 wt%, 0.03 wt%, and 0.01 wt%, respectively, from the top. Similarly to Example 1, when the catalyst treated under the pretreatment conditions described in Reaction Example 6 was analyzed, it was confirmed that particulate Ru was present on the catalyst surface.

<Example 7>
When an MgO powder having a CaO content of 0.001 wt% or less in terms of Ca and having a purity of 99.9 wt% or more is boiled and stirred at 80 ° C. to obtain Mg (OH) ₂ , a Ca (OH) ₂ aqueous solution is dropped simultaneously. By stirring, Ca-added Mg (OH) ₂ particles were obtained. This additive was mixed with 3.0 wt% carbon as a lubricant to form a cylindrical pellet having a diameter of 1/4 inch. The formed pellets were further calcined in air at 1180 ° C. for 3 hours to obtain a catalyst carrier. The obtained catalyst carrier had a BET specific surface area of 0.10 m ² / g.

When the obtained catalyst support was analyzed by ICP in the same manner as in Example 1, the catalyst support contained 0.5 wt% of CaO in terms of Ca. From the EPMA analysis results, it was confirmed that Ca was not present inside the catalyst support, and Ca was present only in the vicinity of the surface of the MgO particles. In addition, the MgO particles constituting the obtained catalyst support were significantly larger than the Ca-added Mg (OH) ₂ particles. Therefore, it is considered that Ca-added Mg (OH) ₂ particles aggregate to form MgO particles, and CaO contained in the Ca-added Mg (OH) ₂ particles is precipitated in the vicinity of the surface of the MgO particles.

The obtained catalyst carrier is in the form of particles, as in Example 1. Part of the surface of the MgO particles is covered with a layer containing CaO, and CaO is present in the recesses on the surface of the MgO particles. It was. Further, these CaOs existed in a region within a depth of 10% from the surface of the catalyst support (that is, near the surface of the MgO particles). When the amount of CaO present on the surface of the MgO particles was determined, it was 50 mg-Ca / m ² in terms of Ca. Moreover, the center part of peanut-like particle | grains contained only trace amount Ca, and most Ca was contained in both ends.

Next, an aqueous ruthenium nitrate solution containing 0.8 wt% Ru is sprayed on the obtained catalyst carrier at 0.15 cc (1.0 times the water absorption amount of the catalyst carrier) with respect to 1.0 g of the catalyst carrier. As a result, a catalyst carrier carrying a catalyst was obtained. The Ru-supported catalyst support thus obtained was dried in an oven at 120 ° C. for 2.5 hours in the air, and then calcined in the electric furnace at 400 ° C. for 2.0 hours in the air to obtain a catalyst.
The obtained catalyst contained Ru at a ratio of 1000 wtppm with respect to the catalyst, and the BET specific surface area was 0.10 m ² / g. Further, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ru was present in the vicinity of the surface of the catalyst particles, that is, in a region within 10% of the depth from the catalyst surface. Therefore, it can be said that CaO exists in the vicinity of the Ru.

<Reaction Example 7>
A reactor similar to that used in Example 1 was charged with 50 cc of the catalyst prepared in Example 7, and an H ₂ O / CO ₂ reforming test for methane was performed.

Specifically, first, the catalyst is prepared by passing a mixed gas of H ₂ and H ₂ O in a molar ratio (H ₂ / H ₂ O = 1/1) in advance through the catalyst layer at 500 ° C. for 1 hour. The reduction process was performed by making it contact. Thereafter, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1: 0.4: 1 is used, the gas pressure at the catalyst layer outlet is 1960 kPaG, the gas temperature at the catalyst layer outlet is 880 ° C., the methane reference GHSV = The treatment was performed at 2,500 / hour.

As a result, the CH ₄ conversion after 5 hours from the start of the reaction was 66.7% (equilibrium conversion of CH ₄ under the experimental conditions = 66.7%), and after 13,000 hours from the start of the reaction. The conversion rate of CH ₄ was 66.7%. Further, after 13000 hours had elapsed, the amount of carbon on the catalyst extracted in four portions in the same manner as in Example 1 was 0.15 wt%, 0.08 wt%, 0.05 wt%, and 0.01 wt%, respectively, from the top. Similarly to Example 1, when the catalyst treated under the pretreatment conditions described in Reaction Example 7 was analyzed, it was confirmed that particulate Ru was present on the catalyst surface.

<Example 8>
When an MgO powder having a CaO content of 0.01 wt% or less in terms of Ca and having a purity of 99.9 wt% or more is boiled and stirred at 100 ° C. to obtain Mg (OH) ₂ , the Ca (OH) ₂ aqueous solution is simultaneously added. Ca-added Mg (OH) ₂ particles were obtained by dropping and stirring. This additive was mixed with 3.0 wt% carbon as a lubricant to form a 1/4 inch diameter pellet. The formed pellets were further calcined in air at 1180 ° C. for 3 hours to obtain a catalyst carrier. The obtained catalyst carrier had a BET specific surface area of 0.10 m ² / g.

The obtained catalyst support was analyzed by ICP in the same manner as in Example 1. As a result, the catalyst support contained 1.4 wt% of CaO in terms of Ca. From the EPMA analysis results, it was confirmed that Ca was not present inside the catalyst support and Ca was present only in the vicinity of the surface of the MgO particles. In addition, the MgO particles constituting the obtained catalyst support were significantly larger than the Ca-added Mg (OH) ₂ particles. Therefore, it is considered that Ca-added Mg (OH) ₂ particles aggregate to form MgO particles, and CaO contained in the Ca-added Mg (OH) ₂ particles is precipitated in the vicinity of the surface of the MgO particles.
The obtained catalyst carrier is in the form of particles, as in Example 1. Part of the surface of the MgO particles is covered with a layer containing CaO, and CaO is present in the recesses on the surface of the MgO particles. It was. Moreover, these CaO existed in the area | region which is within 10% of the depth from the surface of a catalyst support | carrier. When the amount of CaO present on the surface of the MgO particles was determined, it was 140 mg-Ca / m ² in terms of Ca. Moreover, the center part of peanut-like particle | grains contained only trace amount Ca, and most Ca was contained in both ends.

Next, an aqueous ruthenium nitrate solution containing 0.7 wt% Ru is sprayed onto the obtained catalyst carrier at 0.15 cc (1.0 times the water absorption amount of the catalyst carrier) with respect to 1.0 g of the catalyst carrier, Ru was supported on the catalyst support. The Ru-supported catalyst support thus obtained was dried in an oven at 120 ° C. for 2.5 hours in the air, and then calcined in the electric furnace at 400 ° C. for 2.0 hours in the air to obtain a catalyst.

The obtained catalyst contained Ru at a ratio of 910 wtppm with respect to the catalyst, and the BET specific surface area was 0.10 m ² / g. Further, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ru was supported in the vicinity of the surface of the catalyst particles. Ru was present in a region within 10% depth from the catalyst surface (that is, near the surface of the catalyst particles). Therefore, it can be said that CaO exists in the vicinity of the Ru.

<Reaction Example 8>
A reactor similar to that used in Example 1 was charged with 50 cc of the catalyst prepared in Example 8, and a methane H ₂ O / CO ₂ reforming test was performed.

As a result, the CH ₄ conversion after 5 hours from the start of the reaction was 66.7% (equilibrium conversion of CH ₄ under the experimental conditions = 66.7%), and after 9000 hours from the start of the reaction. The conversion rate of CH ₄ was 66.7%. Further, after 9000 hours had passed, the amount of carbon on the catalyst extracted by dividing into 4 parts in the same manner as in Example 1 was 0.21 wt%, 0.15 wt%, 0.08 wt%, and 0.01 wt%, respectively, from the top. Further, as in Example 1, the catalyst treated under the pretreatment conditions described in Reaction Example 8 was analyzed, and it was confirmed that particulate Ru was present on the catalyst surface.

<Example 9>
Inside, MgO powder containing 0.3 wt% CaO in terms of Ca and having a purity of 98.7 wt% or more is mixed with 3.0 wt% carbon as a lubricant to MgO powder, and the diameter is 1/4 inch. A cylindrical pellet was formed. The formed pellets were calcined in air at 1150 ° C. for 3 hours to obtain a catalyst carrier. The obtained catalyst carrier had a BET specific surface area of 0.12 m ² / g.

The obtained catalyst support was analyzed by ICP in the same manner as in Example 1. As a result, the catalyst support contained 0.3 wt% Ca in terms of CaO. From the EPMA analysis results, it was confirmed that Ca was not present inside the catalyst support and Ca was present only in the vicinity of the surface of the MgO particles. Further, the MgO particles constituting the obtained catalyst carrier were significantly larger than the raw material magnesium oxide particles. Therefore, it is considered that the raw material MgO particles aggregate to form MgO particles, and CaO contained in the raw material MgO particles is precipitated in the vicinity of the surface of the MgO particles. The obtained catalyst carrier is in the form of particles as in Example 1, a part of the surface of MgO particles is covered with a layer containing CaO, and CaO is present in the recesses on the surface of MgO particles. Was. Further, these CaOs existed in a region within 10% depth from the surface of the catalyst support. Then, the amount of CaO present on the surface of the MgO particles was determined and found to be 25 mg-Ca / m ² in terms of Ca. Moreover, the center part of peanut-like particle | grains contained only trace amount Ca, and most Ca was contained in both ends.

Next, an aqueous rhodium acetate solution containing 0.81 wt% Rh was sprayed on the obtained catalyst carrier at 0.17 cc (1.1 times the water absorption amount of the catalyst carrier) with respect to 1.0 g of the catalyst carrier, and Rh was A supported catalyst carrier was obtained. The catalyst carrier carrying Rh thus obtained was dried in an oven at 120 ° C. for 2.5 hours in air and then calcined in an electric furnace at 650 ° C. for 2.0 hours in air to obtain a catalyst.

The obtained catalyst contained Rh at a ratio of 1350 wtppm with respect to the catalyst, and its BET specific surface area was 0.12 m ² / g. Further, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Rh was present in the vicinity of the surface of the catalyst particles, that is, within 10% of the depth from the catalyst surface. Therefore, it is considered that CaO exists in the vicinity of the Rh.

<Reaction Example 9>
A reactor similar to that used in Example 1 was charged with 50 cc of the catalyst prepared in Example 9, and a methane H ₂ O / CO ₂ reforming test was performed.

Specifically, first, the catalyst is prepared by passing a mixed gas of H ₂ and H ₂ O in a molar ratio (H ₂ / H ₂ O = 1/0) in advance through the catalyst layer at 500 ° C. for 1 hour. The reduction process was performed by making it contact. Thereafter, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1: 0.4: 1 was treated under the conditions of a pressure of 1960 kPaG, a temperature of 880 ° C., and a methane standard GHSV = 2500 / hour. .

As a result, the CH ₄ conversion after 5 hours from the start of the reaction was 66.7% (equilibrium conversion of CH ₄ under experimental conditions = 66.7%), and after 8000 hours from the start of the reaction. The conversion rate of CH ₄ was 66.7%. Further, after 8000 hours, the amounts of carbon on the catalyst extracted by dividing into 4 parts in the same manner as in Example 1 were 0.15 wt%, 0.07 wt%, 0.05 wt%, and 0.01 wt%, respectively, from the top. . Similarly to Example 1, when the catalyst treated under the pretreatment conditions described in Reaction Example 9 was analyzed, it was confirmed that particulate Rh was present on the catalyst surface.

<Example 10>
When an MgO powder having a CaO content of 0.001 wt% or less in terms of Ca and having a purity of 99.9 wt% or more is boiled and stirred at 100 ° C. to make Mg (OH) ₂ , a Ca (OH) ₂ aqueous solution is dropped simultaneously. By stirring, Ca-added Mg (OH) ₂ particles were obtained. This additive was mixed with 3.0 wt% carbon as a lubricant to form a 1/4 inch diameter pellet. The formed pellets were further calcined in air at 1180 ° C. for 3 hours to obtain a catalyst carrier. The obtained catalyst carrier had a BET specific surface area of 0.10 m ² / g.

The obtained catalyst support was analyzed by ICP in the same manner as in Example 1. As a result, the catalyst support contained 0.01 wt% of CaO in terms of Ca. From the EPMA analysis results, it was confirmed that Ca was not present inside the catalyst support and Ca was present only on the MgO particle surface. In addition, the MgO particles constituting the obtained catalyst support were significantly larger than the Ca-added Mg (OH) ₂ particles. Therefore, it is considered that Ca-added Mg (OH) ₂ particles aggregate to form MgO particles, and CaO contained in the Ca-added Mg (OH) ₂ particles is precipitated on the surface of the MgO particles. The obtained catalyst carrier is in the form of particles as in Example 1, a part of the surface of MgO particles is covered with a layer containing CaO, and CaO is present in the recesses on the surface of MgO particles. Was. Moreover, these CaO existed in the area | region which is within 10% of the depth from the surface of a catalyst support | carrier. When the amount of CaO present on the surface of the MgO particles was determined, it was 1 mg-Ca / m ² in terms of Ca. Moreover, the center part of peanut-like particle | grains contained only trace amount Ca, and most Ca was contained in both ends.

Next, an aqueous ruthenium nitrate solution containing 0.6 wt% Ru is sprayed on the obtained catalyst carrier at 0.15 cc (1.0 times the water absorption amount of the catalyst carrier) with respect to 1.0 g of the catalyst carrier. As a result, a catalyst carrier carrying a catalyst was obtained.

Next, the obtained catalyst carrier carrying Ru was dried in an oven at 120 ° C. for 2.5 hours in air, and then calcined in an electric furnace at 400 ° C. for 2.0 hours in air to obtain a catalyst.

The obtained catalyst contained Ru at a ratio of 780 wtppm with respect to the catalyst, and the BET specific surface area was 0.10 m ² / g. Further, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ru was supported in the vicinity of the surface of the catalyst particles. Ru was present in a region within 10% depth from the catalyst surface. Therefore, it is considered that CaO exists in the vicinity of the Ru.

<Reaction Example 10>
A reactor similar to that used in Example 1 was charged with 50 cc of the catalyst prepared in Example 10, and an H ₂ O / CO ₂ reforming test for methane was performed.

As a result, the CH ₄ conversion rate after 5 hours from the start of the reaction was 66.7% (equilibrium conversion rate of CH ₄ under experimental conditions = 66.7%), and 5000 hours after the start of the reaction. The conversion rate of CH ₄ was 66.7%. Further, after 5000 hours, the amount of carbon on the catalyst extracted by dividing into 4 parts in the same manner as in Example 1 was 0.28 wt%, 0.17 wt%, 0.09 wt%, and 0.01 wt% from the top, respectively. Similarly to Example 1, when the catalyst treated under the pretreatment conditions described in Reaction Example 10 was analyzed, it was confirmed that particulate Ru was present on the catalyst surface.

<Example 11>
Inside, MgO powder containing 0.3 wt% CaO in terms of Ca and having a purity of 98.7 wt% or more is mixed with 3.0 wt% carbon as a lubricant to MgO powder, and the diameter is 1/4 inch. A cylindrical pellet was formed. The formed pellets were calcined in air at 1100 ° C. for 3 hours to obtain a catalyst carrier. The resulting catalyst support had a BET specific surface area of 0.20 m ² / g.

When the obtained catalyst support was analyzed by ICP in the same manner as in Example 1, the catalyst support contained 0.3 wt% of CaO in terms of Ca. From the EPMA analysis results, it was confirmed that Ca was not present inside the catalyst support and Ca was present only in the vicinity of the surface of the MgO particles. Further, the MgO particles constituting the obtained catalyst carrier were significantly larger than the raw material magnesium oxide particles. Therefore, it is considered that the raw material MgO particles aggregate to form MgO particles, and CaO contained in the raw material MgO particles is precipitated on the surface of the MgO particles. The obtained catalyst carrier is in the form of particles as in Example 1, a part of the surface of MgO particles is covered with a layer containing CaO, and CaO is present in the recesses on the surface of MgO particles. Was. Moreover, these CaO existed in the area | region which is within 10% of the depth from the surface of a catalyst support | carrier. When the amount of CaO present on the surface of the MgO particles was determined, it was 15 mg-Ca / m ² in terms of Ca. Moreover, the center part of peanut-like particle | grains contained only trace amount Ca, and most Ca was contained in both ends.

Next, a nickel nitrate hydrate aqueous solution containing 8.0 wt% Ni is added to the obtained catalyst carrier at 0.15 cc (1.0 times the water absorption amount of the catalyst carrier) with respect to 1.0 g of the catalyst carrier. It sprayed and Ni was carry | supported on the catalyst support | carrier. The catalyst carrier carrying Ni thus obtained was dried in air at 120 ° C. for 2.5 hours in the air, and then calcined in air in an electric furnace at 650 ° C. for 2.0 hours to obtain a catalyst.

The obtained catalyst contained Ni at a rate of 10,000 wtppm with respect to the catalyst, and its BET specific surface area was 0.20 m ² / g. Further, when the obtained catalyst was subjected to EPMA analysis in the same manner as in Example 1, Ni and Ca were present in the vicinity of the surface of the catalyst particles, that is, in a region within 10% depth from the catalyst surface.

<Example 12>
Inside, MgO powder containing 0.3 wt% CaO in terms of Ca and having a purity of 98.7 wt% or more is mixed with 3.0 wt% carbon as a lubricant to MgO powder, and the diameter is 1/4 inch. A cylindrical pellet was formed. The formed pellets were calcined in air at 1100 ° C. for 3 hours to obtain a catalyst carrier. The obtained catalyst carrier had a BET specific surface area of 0.10 m ² / g.

The obtained catalyst carrier was analyzed by ICP as in Example 1. As a result, the catalyst carrier contained 0.3 wt% of CaO in terms of Ca. From the EPMA analysis results, it was confirmed that Ca was not present inside the catalyst support and Ca was present only in the vicinity of the surface of the MgO particles. Further, the MgO particles constituting the obtained catalyst carrier were significantly larger than the raw material magnesium oxide particles. Therefore, it is considered that the raw material MgO particles aggregate to form MgO particles, and CaO contained in the raw material MgO particles is precipitated in the vicinity of the surface of the MgO particles.

The obtained catalyst carrier is in the form of particles, as in Example 1. Part of the surface of the MgO particles is covered with a layer containing CaO, and CaO is present in the recesses on the surface of the MgO particles. It was. Moreover, these CaO existed in the area | region which is within 10% of the depth from the surface of a catalyst support | carrier. When the amount of CaO present on the surface of the MgO particles was determined, it was 15 mg-Ca / m ² in terms of Ca. Moreover, the center part of peanut-like particle | grains contained only trace amount Ca, and most Ca was contained in both ends.

Next, an iridium chloride aqueous solution containing 2.7 wt% of Ir is sprayed on the obtained catalyst carrier at 0.15 cc (1.0 times the water absorption amount of the catalyst carrier) with respect to 1.0 g of the catalyst carrier, Ir was supported on the catalyst support. The catalyst carrier loaded with Ir thus obtained was dried in air at 120 ° C. for 2.5 hours in air, and then calcined in air in an electric furnace at 650 ° C. for 2.0 hours to obtain a catalyst.

The obtained catalyst contained Ir at a ratio of 3500 wtppm with respect to the catalyst, and its BET specific surface area was 0.20 m ² / g. Further, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ca and Ir were present in a region close to the surface of the catalyst particles, that is, in a region within 10% of the depth from the catalyst surface.

<Example 13>
Inside, MgO powder containing 0.3 wt% CaO in terms of Ca and having a purity of 98.7 wt% or more is mixed with 3.0 wt% carbon as a lubricant to MgO powder, and the diameter is 1/4 inch. A cylindrical pellet was formed. The formed pellets were calcined in air at 1100 ° C. for 3 hours to obtain a catalyst carrier. The resulting catalyst support had a BET specific surface area of 0.20 m ² / g.

Next, an osmium oxide aqueous solution containing 1.6 wt% Os is sprayed on the obtained catalyst carrier at 0.15 cc (1.0 times the amount of water absorbed by the catalyst carrier) with respect to 1.0 g of the catalyst carrier. Then, Os was supported on the catalyst carrier. The catalyst carrier carrying Os thus obtained was dried in an oven at 120 ° C. for 2.5 hours in air and then calcined in an electric furnace at 650 ° C. for 2.0 hours in air to obtain a catalyst.

The obtained catalyst contained Os at a ratio of 3500 wtppm with respect to the catalyst, and its BET specific surface area was 0.20 m ² / g. Further, when the obtained catalyst was subjected to EPMA analysis in the same manner as in Example 1, Ca and Os were present in the vicinity of the surface of the catalyst particles, that is, in a region within 10% of the depth from the catalyst surface.

<Comparative Example 1>
Inside, MgO powder containing 0.3 wt% CaO in terms of Ca and having a purity of 98.7 wt% or more is mixed with 3.0 wt% carbon as a lubricant to MgO powder, and the diameter is 1/4 inch. A cylindrical pellet was formed. The formed pellets were calcined in air at 600 ° C. for 3 hours to obtain a catalyst carrier.

The obtained catalyst carrier was analyzed by ICP as in Example 1. As a result, the catalyst carrier contained 0.3 wt% of CaO in terms of Ca. The EPMA analysis result of the cross section of the catalyst carrier is shown in FIG. As shown in FIG. 7, the obtained catalyst support is in the form of particles, CaO is uniformly distributed inside the MgO particles, precipitation of MgO particles in the vicinity of the surface is not confirmed, and CaO is in the vicinity of the MgO surface. Did not exist.

Next, an aqueous rhodium acetate solution containing 3.9 wt% Rh was sprayed onto the obtained catalyst carrier at 0.39 cc (1.1 times the water absorption amount of the catalyst carrier) with respect to 1.0 g of the catalyst carrier, A catalyst carrier carrying Rh was obtained. The catalyst carrier carrying Rh thus obtained was dried in an oven at 120 ° C. for 2.5 hours in air and then calcined in an electric furnace at 950 ° C. for 2.0 hours in air to obtain a catalyst.

The obtained catalyst contained Rh at a ratio of 15000 wtppm with respect to the catalyst, and its BET specific surface area was 32.0 m ² / g. Further, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Rh was supported on the surfaces of the catalyst particles. Rh was present within a depth of 10% from the catalyst surface. And Ca was uniformly distributed inside the MgO particles, no precipitation on the surface was confirmed, and no CaO-containing layer was present on the surface. Ca was not present in the vicinity of Rh.

<Comparative Reaction Example 1>
The same reactor used in Example 1 was charged with 50 cc of the catalyst prepared in Comparative Example 1, and a CO ₂ reforming test for methane was performed.

Specifically, first, the catalyst is brought into contact with the catalyst by circulating a mixed gas of H ₂ and H ₂ O in a molar ratio (H ₂ / H ₂ O = 1/3) in advance at 500 ° C. for 1 hour. The reduction treatment was performed. Thereafter, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1: 1: 0 is converted into a catalyst layer outlet gas pressure of 1960 kPaG, a catalyst layer outlet gas temperature of 880 ° C., methane-based GHSV = 2, The treatment was performed at 500 / hour. The CH ₄ conversion after 5 hours from the start of the reaction was 54.8% (CH ₄ equilibrium conversion under experimental conditions = 54.8%), and the CH ₄ conversion after 30 hours was 47.3%. Met. Further, after 30 hours, the amount of carbon on the catalyst extracted by dividing into 4 parts in the same manner as in Example 1 was 3.2 wt%, 2.3 wt%, 2.2 wt%, and 2.1 wt%, respectively, from the top. . Similarly to Example 1, when the catalyst treated under the pretreatment conditions described in Comparative Reaction Example 1 was analyzed, it was confirmed that Rh particles were present on the catalyst surface.

<Comparative Example 2>
A commercially available silica alumina molded body having a CaO content of 0.01 wt% or less in terms of Ca was calcined in air at 950 ° C. for 3 hours to obtain a catalyst carrier. When the obtained catalyst support was analyzed by ICP in the same manner as in Example 1, the CaO content of the catalyst support was 0.01 wt% or less in terms of Ca. In the obtained catalyst carrier, Ca was not present on the surface.

Next, an aqueous rhodium acetate solution containing 0.48 wt% Rh is sprayed onto the obtained catalyst carrier at 0.58 cc (1.2 times the water absorption amount of the catalyst carrier) with respect to 1.0 g of the catalyst carrier, A catalyst carrier silica alumina carrying Rh was obtained. The catalyst carrier carrying Rh thus obtained was dried in an oven at 120 ° C. for 2.5 hours in air and then calcined in an electric furnace at 950 ° C. for 2.0 hours in air to obtain a catalyst.

The obtained catalyst contained Rh at a ratio of 850 wtppm with respect to the catalyst, and its BET specific surface area was 24.0 m ² / g. Further, when the obtained catalyst was subjected to EPMA analysis in the same manner as in Example 1, Ca was not present in the vicinity of Rh.

<Comparative Reaction Example 2>
The same reactor used in Example 1 was charged with 50 cc of the catalyst prepared in Comparative Example 2, and a CO ₂ reforming test for methane was performed.

Specifically, first, the catalyst is prepared by passing a mixed gas of H ₂ and H ₂ O in a molar ratio (H ₂ / H ₂ O = 1/0) in advance through the catalyst layer at 500 ° C. for 1 hour. The reduction process was performed by making it contact. Thereafter, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1: 1: 0 is converted into a catalyst layer outlet gas pressure of 1960 kPaG, a catalyst layer outlet gas temperature of 880 ° C., methane-based GHSV = 2, The treatment was performed at 500 / hour. The CH ₄ conversion after 5 hours from the start of the reaction was 35.3% (equilibrium conversion of CH ₄ under experimental conditions = 54.8%), and the CH ₄ conversion after 20 hours was 28.2%. Met. Further, after 20 hours, the amounts of carbon on the catalyst extracted by dividing into four parts in the same manner as in Example 1 were 1.8 wt%, 1.3 wt%, 0.8 wt%, and 0.5 wt%, respectively, from the top. . Similarly to Example 1, when the catalyst treated under the pretreatment conditions described in Comparative Reaction Example 2 was analyzed, it was confirmed that Rh particles were present on the catalyst surface.

<Comparative Example 3>
A commercially available ZnO molded body having a CaO content of 0.01 wt% or less in terms of Ca was calcined in air at 950 ° C. for 3 hours to obtain a catalyst carrier. When the obtained catalyst support was analyzed by ICP in the same manner as in Example 1, the CaO content of the catalyst support was 0.01 wt% or less in terms of Ca. In the obtained catalyst carrier, Ca was not present on the surface.

Next, an aqueous rhodium acetate solution containing 0.37 wt% Rh is sprayed onto the obtained catalyst carrier at 0.37 cc (1.0 times the water absorption amount of the catalyst carrier) with respect to 1.0 g of the catalyst carrier. As a result, a catalyst carrier ZnO carrying N was obtained. The resulting catalyst carrier carrying Rh had a BET specific surface area of 1.5 m ² / g. Further, when the obtained catalyst carrier carrying Rh was analyzed by EPMA in the same manner as in Example 1, Ca was not unevenly distributed on the surface.

Next, the obtained catalyst carrier ZnO carrying Rh was dried in air at 120 ° C. for 2.5 hours in the air, and then calcined in air in an electric furnace at 950 ° C. for 2.0 hours to obtain a catalyst. . The obtained catalyst contained Rh at a ratio of 900 wtppm with respect to the catalyst, and its BET specific surface area was 1.50 m ² / g. Further, when the obtained catalyst was subjected to EPMA analysis in the same manner as in Example 1, Ca was not present in the vicinity of Rh.

<Comparative Reaction Example 3>
The same reactor used in Example 1 was charged with 50 cc of the catalyst prepared in Comparative Example 3, and a CO ₂ reforming test for methane was performed.

Specifically, first, the catalyst is brought into contact with the catalyst by circulating a mixed gas of H ₂ and H ₂ O in a molar ratio (H ₂ / H ₂ O = 1/2) in advance at 500 ° C. for 1 hour. The reduction treatment was performed. Thereafter, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio = 1: 1: 0) is used, the gas pressure at the catalyst layer outlet is 1960 kPaG, the gas temperature at the catalyst layer outlet is 880 ° C., the methane reference GHSV = 2, The treatment was performed at 500 / hour. The CH ₄ conversion after 5 hours from the start of the reaction is 15.8% (equilibrium conversion of CH ₄ under experimental conditions = 54.8%), and the CH ₄ conversion after 40 hours is 10.2%. Met. In addition, after 40 hours, the amount of carbon on the catalyst extracted by dividing into four parts in the same manner as in Example 1 was 5.5 wt%, 5.1 wt%, 3.2 wt%, and 2.1 wt%, respectively, in order from the top. . Further, as in Example 1, the analysis confirmed that Rh particles were present on the catalyst surface.

<Comparative Example 4>
A commercially available CaO molded body was calcined in air at 950 ° C. for 3 hours to obtain a catalyst carrier. The obtained catalyst support was analyzed by ICP in the same manner as in Example 1. In the obtained catalyst carrier, the constituent component of the carrier itself was CaO.

Next, an aqueous rhodium acetate solution containing 0.3 wt% Rh is sprayed on the obtained catalyst carrier at 0.25 cc (1.1 times the water absorption amount of the catalyst carrier) with respect to 1.0 g of the catalyst carrier, A catalyst carrier carrying Rh was obtained. The catalyst carrier carrying Rh thus obtained was dried in an oven at 120 ° C. for 2.5 hours in air and then calcined in an electric furnace at 950 ° C. for 2.0 hours in air to obtain a catalyst.

The obtained catalyst contained Rh at a ratio of 780 wtppm with respect to the catalyst, and its BET specific surface area was 8.90 m ² / g. Further, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Rh was supported on the surface of the support CaO.

<Comparative Reaction Example 4>
The same reactor used in Example 1 was charged with 50 cc of the catalyst prepared in Comparative Example 4, and a CO ₂ reforming test for methane was performed.

Specifically, first, the catalyst is prepared by passing a mixed gas of H ₂ and H ₂ O in a molar ratio (H ₂ / H ₂ O = 1/5) in advance through the catalyst layer at 500 ° C. for 1 hour. The reduction process was performed by making it contact. Thereafter, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1: 1: 0 is converted into a catalyst layer outlet gas pressure of 1960 kPaG, a catalyst layer outlet gas temperature of 880 ° C., methane-based GHSV = 2, The treatment was performed at 500 / hour. The CH ₄ conversion after 5 hours from the start of the reaction was 25.3% (equilibrium conversion of CH ₄ under experimental conditions = 54.8%), and the CH ₄ conversion after 70 hours was 18.2%. Met. Further, after 70 hours, the amounts of carbon on the catalyst extracted by dividing into 4 parts in the same manner as in Example 1 were 17.4 wt%, 10.3 wt%, 5.1 wt%, and 4.7 wt%, respectively, from the top. . Similarly to Example 1, when the catalyst treated under the pretreatment conditions described in Comparative Reaction Example 4 was analyzed, it was confirmed that particulate Rh was present on the catalyst surface.

<Comparative Example 5>
A commercially available ZrO ₂ molded body having a CaO content of 0.01 wt% or less in terms of Ca was calcined in air at 950 ° C. for 3 hours to obtain a catalyst carrier. When the obtained catalyst support was analyzed by ICP in the same manner as in Example 1, the CaO content of the catalyst support was 0.01 wt% or less in terms of Ca. Further, in the obtained catalyst carrier, Ca was not present on the surface.

Next, an aqueous rhodium acetate solution containing 0.28 wt% Rh is sprayed onto the obtained catalyst carrier at 0.22 cc (1.2 times the amount of water absorbed by the catalyst carrier) with respect to 1.0 g of the catalyst carrier. Thus, a catalyst carrier carrying Rh was obtained. The catalyst carrier carrying Rh thus obtained was dried in an oven at 120 ° C. for 2.5 hours in air and then calcined in an electric furnace at 950 ° C. for 2.0 hours in air to obtain a catalyst.

The obtained catalyst contained Rh at a rate of 900 wtppm with respect to the catalyst, and its BET specific surface area was 4.20 m ² / g. Further, when the obtained catalyst was subjected to EPMA analysis in the same manner as in Example 1, it was confirmed that particulate Ru was present on the catalyst surface.

<Comparative Reaction Example 5>
The same reactor used in Example 1 was charged with 50 cc of the catalyst prepared in Comparative Example 5, and a CO ₂ reforming test for methane was performed.

Specifically, first, the catalyst is brought into contact with the catalyst by circulating a mixed gas of H ₂ and H ₂ O in a molar ratio (H ₂ / H ₂ O = 1/3) in advance at 500 ° C. for 1 hour. After performing the reduction treatment, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1: 1: 0 is used, the gas pressure at the catalyst layer outlet is 1960 kPaG, and the gas temperature at the catalyst layer outlet is 880. The treatment was carried out under the conditions of ℃ and GHSV based on methane = 2500 / hour. The conversion rate of CH ₄ after 5 hours from the start of the reaction was 37.8% (equilibrium conversion rate of CH ₄ under experimental conditions = 54.8%), and the conversion rate of CH ₄ after 10 hours was 30.2%. Met. Further, after 10 hours, the amount of carbon on the catalyst extracted by dividing into 4 parts in the same manner as in Example 1 was 1.5 wt%, 2.3 wt%, 3.2 wt%, and 3.2 wt%, respectively, from the top. . Further, in the same manner as in Example 1, when the analysis was performed under the pretreatment conditions described in Comparative Reaction Example 5, it was confirmed that Rh particles were present on the catalyst surface.

<Comparative Example 6>
A commercially available Al ₂ O ₃ molded body having a CaO content of 0.01 wt% or less in terms of Ca was calcined in the air at 950 ° C. for 3 hours to obtain a catalyst carrier. When the obtained catalyst support was analyzed by ICP in the same manner as in Example 1, the CaO content of the catalyst support was 0.01 wt% or less in terms of Ca. In the obtained catalyst carrier, Ca was not present on the surface.

Next, an aqueous rhodium acetate solution containing 0.16 wt% Rh was sprayed onto the obtained catalyst at 0.75 cc (1.0 times the water absorption amount of the catalyst carrier) with respect to 1.0 g of the catalyst carrier, and Rh As a result, a catalyst carrier carrying a catalyst was obtained. The catalyst carrier carrying Rh thus obtained was dried in an oven at 120 ° C. for 2.5 hours in air and then calcined in an electric furnace at 950 ° C. for 2.0 hours in air to obtain a catalyst.

The obtained catalyst contained Rh at a ratio of 1200 wtppm with respect to the catalyst, and its BET specific surface area was 110.0 m ² / g. Further, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ca was not selectively present in the vicinity of Rh.

<Comparative Reaction Example 6>
The same reactor used in Example 1 was charged with 50 cc of the catalyst prepared in Comparative Example 9, and a CO ₂ reforming test for methane was performed.

Specifically, first, the catalyst is brought into contact with the catalyst by circulating a gas mixture of H ₂ and H ₂ O in a molar ratio (H ₂ / H ₂ O = 1/1) in advance at 500 ° C. for 1 hour. The reduction treatment was performed. Thereafter, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1: 1: 0 is converted into a catalyst layer outlet gas pressure of 1960 kPaG, a catalyst layer outlet gas temperature of 880 ° C., methane-based GHSV = 2, The treatment was performed at 500 / hour. The CH ₄ conversion after 5 hours from the start of the reaction was 54.8% (equilibrium conversion of CH ₄ under experimental conditions = 54.8%), and the CH ₄ conversion after 50 hours was 51.2%. Met. Further, after 50 hours, the amounts of carbon on the catalyst extracted in four portions in the same manner as in Example 1 were 16.1 wt%, 10.3 wt%, 5.2 wt%, and 4.8 wt%, respectively, from the top. . Further, as in Example 1, the analysis confirmed that Rh particles were present on the catalyst surface.

<Comparative Example 7>
A MgO powder having a purity of 99.9 wt% or more with a CaO content of 0.001 wt% or less in terms of Ca is mixed with 3.0 wt% carbon as a lubricant with respect to the MgO powder, and the diameter is 1/4 inch. A cylindrical pellet was formed. The formed pellets were calcined in air at 1100 ° C. for 3 hours to obtain a catalyst carrier. When the obtained catalyst support was analyzed by ICP in the same manner as in Example 1, the CaO content of the catalyst support was 0.001 wt% or less in terms of Ca, and the BET specific surface area was 0.2 m ² / g. Met. Moreover, precipitation of CaO on the surface was not confirmed, and CaO was not present on the catalyst support surface.

Next, an aqueous rhodium acetate solution containing 0.73 wt% Rh was sprayed onto the obtained catalyst carrier at a rate of 0.18 cc (1.2 times the amount of water absorbed by the catalyst carrier) with respect to 1.0 g of the carrier. As a result, a catalyst carrier carrying a catalyst was obtained. The catalyst carrier carrying Rh thus obtained was dried in an oven at 120 ° C. for 2.5 hours in air and then calcined in an electric furnace at 950 ° C. for 2.0 hours in air to obtain a catalyst.

The obtained catalyst contained Rh at a rate of 1300 wtppm with respect to the catalyst, and its BET specific surface area was 0.20 m ² / g. Further, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ca was not present in the vicinity of Rh.

<Comparative Reaction Example 7>
The same reactor used in Example 1 was charged with 50 cc of the catalyst prepared in Comparative Example 7, and a CO ₂ reforming test for methane was performed.

Specifically, first, the catalyst is brought into contact with the catalyst by circulating a mixed gas of H ₂ and H ₂ O in a molar ratio (H ₂ / H ₂ O = 1/3) in advance at 500 ° C. for 1 hour. After performing the reduction treatment, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1: 1: 0 is used, the gas pressure at the catalyst layer outlet is 1960 kPaG, and the gas temperature at the catalyst layer outlet is 880. The treatment was carried out under the conditions of ℃ and GHSV based on methane = 2500 / hour.

As a result, the CH ₄ conversion after 5 hours from the start of the reaction was 54.8% (CH ₄ equilibrium conversion under experimental conditions = 54.8%), and the CH ₄ conversion after 70 hours was 52 3%. Further, after 70 hours, the amounts of carbon on the catalyst extracted in four portions in the same manner as in Example 1 were 6.5 wt%, 3.5 wt%, 3.2 wt%, and 2.4 wt%, respectively, from the top. . Further, as in Example 1, the analysis confirmed that Rh particles were present on the catalyst surface.

<Comparative Example 8>
A MgO powder having a purity of 99.9 wt% or more with a CaO content of 0.001 wt% or less in terms of Ca is mixed with 3.0 wt% carbon as a lubricant to the MgO powder, and the diameter is 1/4 inch. A cylindrical pellet was formed. The formed pellets were calcined in air at 1100 ° C. for 3 hours to obtain a catalyst carrier. When the obtained catalyst support was analyzed by ICP in the same manner as in Example 1, the CaO content of the catalyst support was 0.001 wt% or less in terms of Ca. Moreover, precipitation of CaO on the surface of the obtained catalyst carrier was not confirmed, and CaO was not present on the surface of the catalyst carrier.

Next, an aqueous rhodium acetate solution containing 0.87 wt% Rh is sprayed onto the obtained catalyst carrier at 0.15 cc (1.0 times the water absorption amount of the catalyst carrier) with respect to 1.0 g of the carrier, A supported catalyst carrier was obtained. The catalyst carrier carrying Rh thus obtained was dried in an oven at 120 ° C. for 2.5 hours in the air, and then an aqueous chloroplatinic acid solution containing 0.5 wt% Pt was added to 1.0 g of the carrier. Spraying was performed at 15 cc (1.0 times the amount of water absorbed by the catalyst carrier) to obtain a catalyst carrier carrying Rh and Pt. The obtained catalyst carrier carrying Rh and Pt was calcined in air in an electric furnace at 950 ° C. for 2.0 hours to obtain a catalyst.

The obtained catalyst contained Rh in a proportion of 1300 wtppm with respect to the catalyst and Pt in a proportion of 750 wtppm with respect to the catalyst, and its BET specific surface area was 0.20 m ² / g. Further, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ca was not present in the vicinity of Rh and Pt.

<Comparative Reaction Example 8>
50 cc of the catalyst prepared in Comparative Example 11 was charged into the same reactor as that used in Example 1, and a CO ₂ reforming test of methane was performed.

Specifically, first, the catalyst is brought into contact with the catalyst by circulating a mixed gas of H ₂ and H ₂ O in a molar ratio (H ₂ / H ₂ O = 1/3) in advance at 500 ° C. for 1 hour. The reduction treatment was performed. Thereafter, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1: 1: 0 is converted into a catalyst layer outlet gas pressure of 1960 kPaG, a catalyst layer outlet gas temperature of 880 ° C., methane-based GHSV = 2, The treatment was performed at 500 / hour. The CH ₄ conversion after 5 hours from the start of the reaction was 54.8% (CH ₄ equilibrium conversion under experimental conditions = 54.8%), and the CH ₄ conversion after 15 hours was 54.8%. Met. Further, after 15 hours, the amount of carbon on the catalyst extracted in four portions in the same manner as in Example 1 was 1.6 wt%, 2.3 wt%, 3.2 wt%, and 2.7 wt% in order from the top. . Similarly to Example 1, when the catalyst treated under the pretreatment conditions described in Comparative Reaction Example 8 was analyzed, it was confirmed that Rh particles were present on the catalyst surface.

<Comparative Example 9>
A cylinder having a CaO content of 0.001 wt% or less and a purity of 99.9 wt% or more mixed with 3.0 wt% of carbon as the lubricant and MgO powder as a lubricant, and having a 1/4 inch diameter cylinder Shaped pellets were formed. A lanthanum nitrate aqueous solution containing 5.1 wt% La was sprayed on the formed pellets to support La, and further calcined in air at 1100 ° C. for 3 hours to obtain a catalyst carrier. The obtained catalyst support was analyzed by ICP in the same manner as in Example 1. As a result, the La content of the catalyst support was 1.5 wt%, and the CaO content was 0.001 wt% or less in terms of Ca. . Moreover, precipitation of CaO on the surface of the obtained catalyst carrier was not confirmed, and CaO was not present on the surface of the catalyst carrier.

Next, an aqueous rhodium acetate solution containing 0.67 wt% Rh is sprayed onto the obtained catalyst carrier at 0.20 cc (1.3 times the amount of water absorbed by the catalyst carrier) with respect to 1.0 g of the carrier. A supported catalyst carrier was obtained. The catalyst carrier carrying Rh thus obtained was dried in an oven at 120 ° C. for 2.5 hours in the air, and further calcined in an electric furnace at 950 ° C. for 2.0 hours in the air to obtain a catalyst.

The obtained catalyst contained Rh at a rate of 1300 wtppm with respect to the catalyst, and its BET specific surface area was 0.20 m ² / g. Further, when the obtained catalyst was subjected to EPMA analysis in the same manner as in Example 1, Ca and La were not present in the vicinity of Rh.

<Comparative Reaction Example 9>
The same reactor used in Example 1 was charged with 50 cc of the catalyst prepared in Comparative Example 12, and a CO ₂ reforming test for methane was performed.

Specifically, first, the catalyst is brought into contact with the catalyst by circulating a gas mixture of H ₂ and H ₂ O in a molar ratio (H ₂ / H ₂ O = 1/0) in advance at 500 ° C. for 1 hour. After performing the reduction treatment, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1: 1: 0 is used, the gas pressure at the catalyst layer outlet is 1960 kPaG, and the gas temperature at the catalyst layer outlet is 880. The treatment was carried out under the conditions of ℃ and GHSV based on methane = 2500 / hour. The CH ₄ conversion after 5 hours from the start of the reaction was 54.8% (equilibrium conversion of CH ₄ under experimental conditions = 54.8%), and the CH ₄ conversion after 50 hours was 54.8%. Met. Further, after 50 hours, the amounts of carbon on the catalyst extracted by dividing into 4 parts as in Example 1 were 7.2 wt%, 5.1 wt%, 2.1 wt%, and 1.2 wt%, respectively, from the top. . Similarly to Example 1, analysis of the catalyst treated under the pretreatment conditions described in Comparative Reaction Example 9 confirmed that Rh particles were present on the catalyst surface.

<Comparative Example 10>
When an MgO powder having a CaO content of 0.001 wt% or less in terms of Ca and having a purity of 99.9 wt% or more is boiled and stirred at 100 ° C. to make Mg (OH) ₂ , a Ca (OH) ₂ aqueous solution is dropped simultaneously. By stirring, Ca-added Mg (OH) ₂ particles were obtained. This additive was mixed with 3.0 wt% carbon as a lubricant to form a cylindrical pellet having a diameter of 1/4 inch. The formed pellets were further calcined in air at 1180 ° C. for 3 hours to obtain a catalyst carrier. The obtained catalyst carrier had a BET specific surface area of 0.10 m ² / g.

When the obtained catalyst support was analyzed by ICP in the same manner as in Example 1, the CaO content of the catalyst support was 1.8 wt%. From the EPMA analysis results, it was confirmed that Ca was not present inside the catalyst support and Ca was present only in the vicinity of the MgO particle surface. In addition, the MgO particles constituting the obtained catalyst support were significantly larger than the Ca-added Mg (OH) ₂ particles. Therefore, it is considered that Ca-added Mg (OH) ₂ particles aggregate to form MgO particles, and CaO contained in the Ca-added Mg (OH) ₂ particles is precipitated in the vicinity of the surface of the MgO particles. The obtained catalyst carrier is in the form of particles as in Example 1, a part of the surface of MgO particles is covered with a layer containing CaO, and CaO is present in the recesses on the surface of MgO particles. Was. Moreover, these CaO existed in the area | region which is within 10% of the depth from the surface of a catalyst support | carrier. When the amount of CaO present on the surface of the MgO particles was determined, it was 180 mg-Ca / m ² in terms of Ca. Moreover, the center part of peanut-like particle | grains contained only trace amount Ca, and most Ca was contained in both ends.

Next, an aqueous rhodium acetate solution containing 0.87 wt% Rh is sprayed onto the obtained catalyst carrier at 0.15 cc (1.0 times the water absorption amount of the catalyst carrier) with respect to 1.0 g of the catalyst carrier, A catalyst carrier carrying Rh was obtained. Next, the obtained catalyst support carrying Rh was dried in an oven at 120 ° C. for 2.5 hours in the air, and further calcined in an electric furnace at 950 ° C. for 2.0 hours in the air to obtain a catalyst. It was.

The obtained catalyst contained Rh at a rate of 1300 wtppm with respect to the catalyst, and its BET specific surface area was 0.10 m ² / g. Further, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Rh was supported on the surfaces of the catalyst particles. Rh was present in a region within 10% of the depth from the catalyst surface. Therefore, it is considered that CaO exists in the vicinity of the Rh.

<Comparative Reaction Example 10>
50 cc of the catalyst prepared in Comparative Example 10 was charged into the same reactor as that used in Example 1, and a CO ₂ reforming test of methane was performed.

Specifically, first, the catalyst is brought into contact with the catalyst by circulating a gas mixture of H ₂ and H ₂ O in a molar ratio (H ₂ / H ₂ O = 1/0) in advance at 500 ° C. for 1 hour. After performing the reduction treatment, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1: 1: 0 is used, the gas pressure at the catalyst layer outlet is 1960 kPaG, and the gas temperature at the catalyst layer outlet is 880. The treatment was carried out under the conditions of ℃ and GHSV based on methane = 2500 / hour. The CH ₄ conversion after 5 hours from the start of the reaction was 53.9% (equilibrium conversion of CH ₄ under experimental conditions = 54.8%), and the CH ₄ conversion after 5 hours was 53.1%. Met. Further, after 50 hours, the amounts of carbon on the catalyst extracted in four portions in the same manner as in Example 1 were 0.6 wt%, 0.4 wt%, 0.1 wt%, and 0.05 wt%, respectively, from the top. . Further, when the catalyst treated under the pretreatment conditions described in the comparative reaction example was analyzed, it was confirmed that particulate Rh was present on the catalyst surface.

<Comparative Example 11>
When an MgO powder having a CaO content of 0.001 wt% or less in terms of Ca and having a purity of 99.9 wt% or more is boiled and stirred at 100 ° C. to make Mg (OH) ₂ , a Ca (OH) ₂ aqueous solution is dropped simultaneously. By stirring, Ca-added Mg (OH) ₂ particles were obtained. This additive was mixed with 3.0 wt% carbon as a lubricant to form a 1/4 inch diameter pellet. The formed pellets were further calcined in air at 1060 ° C. for 3 hours to obtain a catalyst carrier. The resulting catalyst support had a BET specific surface area of 0.50 m ² / g.

The obtained catalyst support was analyzed by ICP in the same manner as in Example 1. As a result, the catalyst support contained 0.001 wt% of CaO in terms of Ca. From the EPMA analysis results, it was confirmed that Ca was not present inside the catalyst support and Ca was present only in the vicinity of the surface of the MgO particles. In addition, the MgO particles constituting the obtained catalyst support were significantly larger than the Ca-added Mg (OH) ₂ particles. Therefore, it is considered that Ca-added Mg (OH) ₂ particles aggregate to form MgO particles, and CaO contained in the Ca-added Mg (OH) ₂ particles is precipitated in the vicinity of the surface of the MgO particles. The obtained catalyst carrier is in the form of particles as in Example 1, a part of the surface of MgO particles is covered with a layer containing CaO, and CaO is present in the recesses on the surface of MgO particles. Was. Moreover, these CaO existed in the area | region which is within 10% of the depth from the surface of a catalyst support | carrier. The amount of CaO present on the surface of the MgO particles was determined to be 0.02 mg-Ca / m ² in terms of Ca. Moreover, the center part of peanut-like particle | grains contained only trace amount Ca, and most Ca was contained in both ends.

Next, an aqueous ruthenium nitrate solution containing 0.7 wt% Ru is sprayed onto the obtained catalyst carrier at 0.15 cc (1.0 times the water absorption amount of the catalyst carrier) with respect to 1.0 g of the catalyst carrier. As a result, a catalyst carrier carrying a catalyst was obtained. Next, the obtained catalyst support carrying Ru was dried in an oven at 120 ° C. for 2.5 hours in air, and then calcined in an electric furnace at 400 ° C. for 2.0 hours in air to obtain a catalyst.

The obtained catalyst contained Ru at a ratio of 910 wtppm with respect to the catalyst, and the BET specific surface area was 0.10 m ² / g. Further, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ru was supported on the surfaces of the catalyst particles. And Ru existed in the region within 10% depth from the catalyst surface. Therefore, it is considered that CaO exists in the vicinity of the Ru.

<Comparative Reaction Example 11>
50 cc of the catalyst prepared in Comparative Example 11 was charged into the same reactor as that used in Example 1, and a CO ₂ reforming test of methane was performed.

Specifically, first, the catalyst is brought into contact with the catalyst by circulating a gas mixture of H ₂ and H ₂ O in a molar ratio (H ₂ / H ₂ O = 1/0) in advance at 500 ° C. for 1 hour. After performing the reduction treatment, a raw material gas of CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1: 1: 0 is used, the gas pressure at the catalyst layer outlet is 1960 kPaG, and the gas temperature at the catalyst layer outlet is 880. The treatment was carried out under the conditions of ℃ and GHSV based on methane = 2500 / hour. The CH ₄ conversion after 5 hours from the start of the reaction was 53.9% (equilibrium conversion of CH ₄ under experimental conditions = 54.8%), and the CH ₄ conversion after 50 hours was 53.3%. Met. Further, after 50 hours, the amounts of carbon on the catalyst extracted by dividing into four parts in the same manner as in Example 1 were 0.5 wt%, 0.5 wt%, 0.1 wt%, and 0.05 wt%, respectively, from the top. . Further, when the catalyst treated under the pretreatment conditions described in Comparative Reaction Example 11 was analyzed, it was confirmed that particulate Ru was present on the catalyst surface.

The production conditions of Examples 1 to 13 and Comparative Examples 1 to 11, the properties of the obtained carriers and catalysts are shown in Table 3, and the conditions and results of Reaction Examples 1 to 10 and Comparative Reaction Examples 1 to 11 are shown in Table 4. . As shown in Tables 3 and 4, in the CO ₂ reforming reaction using the catalysts of Examples 1 to 10 produced using the catalyst carrier of the present invention, the amount of carbon deposited was remarkably low (Reaction Examples 1 to 4). 10). And even if it ventilated for a long time, the methane conversion rate was maintained and the synthesis gas was manufactured stably and efficiently for a long period of time.

On the other hand, Comparative Example 1 in which the firing temperature was low and CaO did not precipitate on the surface of MgO particles, Comparative Examples 2 to 6 in which the carrier did not contain MgO, and Comparative Examples 7 to 11 in which the amount of CaO contained was outside the scope of the present invention, A large amount of carbon was deposited, and carbon was deposited in a short time (see Comparative Reaction Examples 1 to 11). In Comparative Examples 1 and 3 to 8, the CH ₄ conversion was also lower than that of the Examples.

Examples 11 to 13 show examples in which a catalyst was produced by supporting a catalyst metal other than Rh and Ru using the catalyst carrier of the present invention. These catalysts can be used for reactions other than the CO ₂ reforming reaction, and at that time, it is considered that the precipitation of carbon can be suppressed.

This application claims priority from Japanese Patent Application No. 2016-116206 filed on June 10, 2016, the contents of which are incorporated herein by reference.

10 Support for synthesis gas production catalyst 11

Magnesium oxide particles

12, 13 Calcium oxide-containing layer

Claims

A magnesia catalyst carrier,
It contains magnesium oxide particles and calcium oxide present in the vicinity of the surface of the magnesium oxide particles, and the content of the calcium oxide with respect to the entire particles is 0.005% by mass to 1.5% by mass in terms of Ca. A characteristic catalyst carrier.
The catalyst carrier according to claim 1, wherein the calcium oxide content per unit surface area of the magnesium oxide particles is 0.05 mg-Ca / m 2 to 150 mg-Ca / m 2 in terms of Ca.
3. The catalyst carrier according to claim 1 or 2, wherein the vicinity of the surface of the magnesium oxide particles is a region whose depth from the surface is within 10% of the maximum depth of each particle.
The catalyst carrier according to any one of claims 1 to 3, wherein the vicinity of the surface of the magnesium oxide particles forms a calcium oxide-containing layer.
A method for producing a magnesia-based catalyst carrier, comprising:
By including the step of firing the raw material magnesium oxide particles containing calcium oxide at 1000 ° C. or higher, the raw material magnesium oxide particles are aggregated to form magnesium oxide particles, and calcium oxide is formed near the surface of the magnesium oxide particles. Precipitating to obtain a catalyst carrier that contains calcium oxide in the vicinity of the surface of the magnesium oxide particles, and that the content of the calcium oxide is 0.005 mass% to 1.5 mass% in terms of Ca. A process for producing a catalyst carrier characterized by the above.
6. The method for producing a catalyst carrier according to claim 5, wherein carbon is added to the raw material magnesium oxide particles within a range of 1% by mass to 5% by mass and then calcined.
7. The catalyst support according to claim 5, wherein a calcium oxide content per unit surface area of the magnesium oxide particles is 0.05 mg-Ca / m 2 to 150 mg-Ca / m 2 in terms of Ca. A method for producing a catalyst carrier as described in 1. above.
The catalyst support according to any one of claims 5 to 7, wherein the vicinity of the surface of the magnesium oxide particles is a region whose depth from the surface is within 10% of the maximum depth of each particle. A method for producing a catalyst carrier as described in 1. above.
The method for producing a catalyst carrier according to any one of claims 5 to 8, wherein in the catalyst carrier, the vicinity of the surface of the magnesium oxide particles forms a calcium oxide-containing layer.