TW201811429A - Magnesia based catalyst carrier and method of manufacturing the same - Google Patents

Abstract

To provide a catalyst carrier that can prevent carbon deposition on a catalyst when used for a gas phase organic reaction, and allows the gas phase organic reaction to be conducted stably and effectively for a long time. A magnesia catalyst carrier contains calcium oxide in the vicinity of the surface of a magnesium oxide particle, and a content of the calcium oxide relative to the whole particle is 0.005 mass% to 1.5 mass% in terms of Ca.

Description

   Magnesium oxide-based catalyst carrier and manufacturing method thereof   

The present invention relates to a magnesium oxide-based catalyst carrier, and more specifically, to a catalyst carrier having a form in which calcium oxide (calcia) precipitates near the surface of the magnesium oxide particles. The magnesium oxide-based catalyst carrier of the present invention is suitable as a catalyst that may be used in a gas-phase organic reaction, in particular, a reaction that may cause carbon deposition doubt on a catalyst for producing synthetic gas by reforming natural gas. Carrier use.

Synthetic gases containing carbon monoxide and hydrogen as main components are widely used as raw materials for dimethyl ether, methanol, Fischer-Tropsch synthetic oil, acetic acid, diphenylmethane diisocyanate, methyl methacrylate, and the like. This synthetic gas, for example, is modified by carbon dioxide that reacts natural gas (light hydrocarbons represented by methane as the main component) with carbon dioxide in the presence of a catalyst, or natural gas and steam in the presence of a catalyst ( Water vapor) is used for steam modification, or carbon dioxide / steam modification for reacting natural gas with carbon dioxide and steam in the presence of a catalyst to produce more.

At this time, when carbon dioxide is reformed or carbon dioxide / steam is reformed, there is a problem that the light hydrocarbons in the raw material react with one of the carbon oxides of the product, and carbon is easily precipitated on the catalyst. When the carbon is deposited on the catalyst, the catalyst activity is impaired and the reaction rate is reduced. Therefore, it can be stable for a long period of time, has good efficiency, and it is difficult to produce a synthetic gas. In addition, carbon precipitation also becomes the cause of the rise or blockage of the differential pressure in the reforming reactor.

The problem of carbon precipitation is caused by a catalyst. For example, there is a carbon dioxide reforming catalyst that supports a ruthenium compound on a carrier made of at least one or more compounds of alkaline earth metal oxides and alumina (see Patent Document 1). ) Or on a carrier made of a metal oxide of the Group 2 to Group 4 or a metal oxide of the lanthanide series or a carrier made of a composite of alumina containing their metal oxides A carbon dioxide reforming catalyst (see Patent Document 2) or a carrier made of a metal oxide supporting at least one catalyst metal selected from the group consisting of rhodium, ruthenium, iridium, palladium, and platinum, with a specific surface area of 25 m ² / g, the electronegativity of the metal ions in the carrier metal oxide is 13.0 or less, and the supported amount of the catalyst metal is calculated in terms of metal conversion, and the synthesis is 0.0005 to 0.1 mole% relative to the carrier metal oxide. A catalyst for gas production (see Patent Document 3) is known.

In addition, the carbon dioxide / steam modification of natural gas (methane) is based on the molar ratio of carbon dioxide or steam to methane in the feed gas, as shown in Figure 1 to change the ratio (volume ratio) of the feed gas to the generated synthesis gas. Therefore, the molar ratio of carbon dioxide / steam to methane in the raw material gas is adjusted to improve the ratio (volume ratio) of the raw material gas to the generated synthesis gas, which is better from the viewpoint of synthesis efficiency. However, when the modification is carried out with the molar ratio of carbon dioxide / vapor in the raw material gas to methane, there is a difficulty that carbon precipitation is very likely to occur on the catalyst surface.

As described above, carbon precipitation is caused by a catalyst problem, and in many cases, an obstacle is caused when performing a gas-phase organic reaction under conditions of high efficiency, and this is not limited to the problem of carbon dioxide modification or carbon dioxide / vapor modification. That is, if there is a catalyst carrier in which carbon is not easily precipitated, the possibility of efficiently performing many gas-phase organic reactions is extremely widened.

    [Prior technical literature]         [Patent Literature]    

[Patent Document 1] Japanese Unexamined Patent Publication No. 6-279003

[Patent Document 2] Japanese Unexamined Patent Publication No. 9-168740

[Patent Document 3] Japanese Patent No. 3345782

The present invention is based on the above-mentioned viewpoint. The present invention provides an organic reaction in a gas phase, and particularly in a reaction that easily causes carbon precipitation due to the decomposition or modification of a hydrocarbon containing carbon dioxide modified such as natural gas (methane). The purpose is to analyze the catalyst carrier on the catalyst used.

As a result of careful research by the present inventors, it was found that by providing magnesium oxide particles and calcium oxide existing near the surface thereof, the content of the calcium oxide relative to the entire particle is 0.005 mass% to 1.5 mass% in terms of Ca. The magnesium oxide-based catalyst carrier can achieve the above-mentioned objective and complete 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 vicinity of the surface of the magnesium oxide particles is preferably a region within a depth of 10% of the maximum depth of each particle.

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

The method for manufacturing a magnesium oxide-based catalyst carrier according to the present invention is characterized in that, by the step of calcining a raw material magnesium oxide particle containing calcium oxide at a temperature of 1000 ° C or higher, the raw material magnesium oxide particle is aggregated or fused to form At the same time, the magnesium oxide particles precipitate calcium oxide near the surface of the magnesium oxide particles, and calcium oxide is contained near the surface of the magnesium oxide particles. The content of the calcium oxide relative to the entire particle is 0.005 mass% to 1.5 in terms of Ca. Mass% catalyst carrier.

In the aforementioned method, it is preferable that carbon is added in a range of 1% by mass to 5% by mass with respect to the raw material magnesium oxide particles, and then calcined.

In the foregoing method, the catalyst carrier is a calcium oxide content per unit surface area of the magnesium oxide particles, and is preferably 0.05 mg-Ca / m ² to 150 mg-Ca / m ^{2 in terms of} Ca.

In the aforementioned method, the catalyst carrier is preferably in a region near the surface of the magnesium oxide particle, and the depth from the surface is within 10% of the maximum depth of each particle.

In the foregoing method, it is preferable that a calcium oxide-containing layer is formed near the surface of the magnesium oxide particles.

When the magnesium oxide-based catalyst carrier of the present invention is used, carbon precipitation can be significantly inhibited from occurring on the catalyst. Therefore, it is possible to perform a gas-phase organic reaction that is suspected of carbon precipitation for a long period of time with good stability.

10‧‧‧Carrier for synthetic gas manufacturing catalyst

11‧‧‧magnesium oxide particles

12, 13‧‧‧ containing calcium oxide layer

[Fig. 1] A diagram showing the relationship between the presence ratio (molar ratio) of carbon dioxide or vapor to carbon in carbon dioxide / steam reforming and the ratio (volume ratio) of the raw material gas to the generated synthesis gas.

Fig. 2 is a schematic diagram showing an example of a cross-sectional shape of magnesium oxide particles constituting a catalyst carrier of the present invention.

3 is a schematic view showing a state in which calcium oxide exists near the surface of magnesium oxide particles constituting the catalyst carrier of the present invention.

[Fig. 4] EPMA analysis result of the carrier for a catalyst for manufacturing a synthetic gas in Example 1;

[Figure 5] EPMA analysis results of the synthetic gas manufacturing catalyst of Example 1.

[Fig. 6] The results of elemental analysis of the synthetic gas production catalyst after the reduction treatment in Example 1 by EDX.

[Fig. 7] EPMA analysis result of the synthetic gas production catalyst of Comparative Example 1. [Fig.

The magnesium oxide-based catalyst carrier of the present invention contains calcium oxide near the surface of the magnesium oxide particles, and the content of the calcium oxide relative to the entire particle is 0.005 mass% to 1.5 mass% in terms of Ca conversion.

The form of the magnesium oxide particles constituting the magnesium oxide-based catalyst carrier of the present invention is not particularly limited, and each particle constituting the raw material magnesium oxide may exist individually or a plurality of particles may be aggregated. FIG. 2 schematically shows an example of a cross-sectional shape of the magnesium oxide particles constituting the catalyst carrier of the present invention. As shown in FIG. 2, the shape of the magnesium oxide particles includes a spherical shape formed by aggregating a plurality of particles constituting the raw material magnesium oxide and then melting each other (FIG. 2 (a)), and agglomeration and fusion of the two particles constituting the raw material magnesium oxide. It is formed in a shape of a peanut (FIG. 2 (b)) composed of a central portion 51 and two end portions 52 having a larger diameter than the central portion 51 (FIG. 2 (b)), and three particles constituting the raw material magnesium oxide are aggregated and fused (FIG. 2 ( c)) etc. In addition, the catalyst carrier of the present invention needs to be formed of magnesium oxide-based particles, that is, particles containing magnesium oxide as a main component, and other metal oxides such as zirconia (ZnO), alumina (Al ₂ O ₃ ), etc. The principal component cannot obtain the effect of this case.

The catalyst carrier of the present invention contains calcium oxide (CaO) near the surface of the magnesium oxide (MgO) particles, but the existence form of the calcium oxide can be various. For example, a calcium oxide-containing layer may be formed in a region near all or part of the surface of the magnesium oxide particles. Further, the calcium oxide-containing layer formed in the vicinity of the surface of the magnesium oxide particles as described above may contain magnesium oxide, or may have a form in which the surface of the magnesium oxide particles is covered with only a layer made of calcium oxide. In addition, the calcium oxide may be partially localized on the surface of the magnesium oxide particles, and for example, calcium oxide may be locally present in the concave portion on the surface of the magnesium oxide particles. FIG. 3 schematically shows an example of the form of calcium oxide on the surface of the magnesium oxide particles in the catalyst carrier of the present invention. As shown in FIG. 3, the catalyst carrier 10 may be a calcium oxide-containing layer 12 formed on the entire surface of the magnesium oxide particles 11 (FIG. 3 (a)) or a portion of the surface of the magnesium oxide particles 11 formed with calcium oxide. In the layer 13 (FIG. 3 (b)), calcium oxide may be locally present in a concave portion on the surface of the magnesium oxide particles.

The catalyst carrier of the present invention thus contains calcium oxide near the surface of the magnesium oxide particles. In addition, the calcium oxide existing in the vicinity of the surface of the magnesium oxide particles is 0.005 mass% to 1.5 mass%, particularly 0.3 mass% to 1.4 mass% in terms of Ca in terms of the entire content of the particles. With this configuration, carbon deposition during the gas-phase organic reaction that may be accompanied by carbon deposition such as carbon dioxide reforming or carbon dioxide / vapor reforming can be significantly suppressed, and stable and efficient implementation can be expected for a long period of time. Gas-phase organic reactions. When the calcium oxide existing near the surface of the magnesium oxide particles is less than 0.005% by mass in terms of Ca in terms of the total content of the particles, carbon precipitation is likely to occur on the catalyst surface, and the amount of Ca in terms of Ca is more than 1.5. In the case of% by mass, the catalyst activity decreases, and the effects of the present invention cannot be obtained.

The content of calcium oxide existing in the vicinity of the surface of the magnesium oxide particles in terms of Ca relative to the entire particle can be determined by the following method. That is, it is sufficient to dissolve the sample (catalyst carrier) with aqua regia and calculate the total Ca content in terms of Ca existing in the magnesium oxide particles by the ICP emission analysis device. At this time, the distribution of Ca existing in the magnesium oxide particles was analyzed by EPMA (electron probe micro analysis), and the presence of almost all Ca in the magnesium oxide particles was confirmed by the EPMA analysis. Near the surface of the particles, the amount of Ca quantified by the ICP emission analysis can be used as the Ca-calculated content of calcium oxide existing near 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. Divide the Ca-equivalent content of calcium oxide (unit: mg-Ca) per 1 g of magnesium oxide particles near the surface by the specific surface area (unit: m ² / g) of the magnesium oxide particles (catalyst carrier) The Ca conversion content (mg-Ca / m ² ) of calcium oxide per unit surface area of the magnesium oxide particles was obtained.

Calcium oxide exists 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, the "near the surface" where calcium oxide exists is within 10% of the maximum depth of each particle The area is better. At this time, "the depth from the surface is within 10% of the maximum depth of each particle" means that any point in the area of each particle is within 10% of the maximum depth of the particle. More correctly refers to the distance between the center of gravity of each particle and the surface furthest from the center of gravity, which is called the maximum depth of the particle. When using this as the radius r ₁ , any point in the area is from the surface of the catalyst carrier and faces the center of gravity. , the distance r _1/10 does not leave.

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, ring-shaped, porous, ingot-shaped, or granular.

The magnesium oxide-based catalyst carrier of the present invention can be calcined at 1000 ° C or higher for raw material magnesium oxide particles containing calcium oxide to aggregate the raw material magnesium oxide particles to form magnesium oxide particles, and at the same time, calcium oxide can be precipitated. It is manufactured near the surface of the magnesium oxide particles.

That is, the manufacturing method of the catalyst carrier of this invention uses the raw material magnesium oxide particle containing a calcium oxide. In addition, the calcium oxide content contained in the raw material magnesium oxide particles is 0.005 mass% to 1.5 mass%, and particularly 0.3 mass% to 1.4 mass%. The "raw calcium oxide-containing raw material magnesium oxide particles" herein means raw magnesium oxide particles used as a raw material, and the inside thereof uniformly contains, for example, calcium oxide in a range of 0.005% to 1.5% by mass. Therefore, high-purity magnesia such as commercially available magnesia, which has been conventionally used, has a small amount of calcium oxide, and therefore it cannot be used as a raw material magnesia particle in the present invention.

The raw material magnesium oxide particles containing such calcium oxide may, if necessary, be formed into the shape of a desired catalyst carrier, such as a ring shape, a porous shape, an ingot shape, or a granular shape.

During molding, a lubricant such as carbon can be added. For example, it is preferable to add carbon in a range of 1% by mass to 5% by mass relative to the raw material magnesium oxide particles.

If necessary, by calcining raw magnesium oxide particles containing the formed calcium oxide at 1000 ° C or higher, the raw magnesium oxide particles are aggregated to form magnesium oxide particles, and at the same time, calcium oxide is precipitated on the surface of the magnesium oxide particles. Manufacture of the catalyst carrier of the present invention.

When the raw magnesium oxide particles are calcined under specific conditions described in detail below, the raw magnesium oxide particles aggregate to form magnesium oxide particles. In addition, by calcination under these specific conditions, calcium oxide existing inside the raw material magnesium oxide particles will exude to the surface, and the calcium oxide will precipitate near the surface of the magnesium oxide particles, and form near the surface of the magnesium oxide particles. A calcium oxide-containing layer, or a concave portion locally present 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 near the surface is insufficient, and the effect of significantly suppressing carbon precipitation of the present invention cannot be obtained.

The firing temperature must be 1000 ° C or higher. When the calcination temperature is low, calcium oxide existing inside the raw material magnesium oxide particles does not precipitate out 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 may be produced by a method other than the above. Specifically, Mg (OH) _{2 is} obtained by stirring high-purity magnesium oxide (for example, MgO having a CaO content of 0.01% by mass or less in terms of Ca and a purity of 99.9% by mass or more) while boiling at 60 to 80 ° C. At the same time, an aqueous solution of Ca (OH) ₂ was dropped and stirred to obtain Ca-added Mg (OH) ₂ particles. The Ca-added Mg (OH) ₂ particles thus obtained contained CaO substantially uniformly in the interior. In addition, the obtained Ca-added Mg (OH) ₂ particles are the same as the above-mentioned production method, and if necessary, by adding a lubricating material or forming, calcination is performed at a temperature of 1000 ° C. or higher, preferably 1400 ° C. or lower, to make Ca-added Mg The (OH) ₂ particles aggregate to form magnesium oxide particles, and at the same time, calcium oxide is precipitated near the surface of the magnesium oxide particles, and the catalyst carrier of the present invention can be produced.

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

Here, the conditions for calcining the raw magnesium oxide particles, Ca-added Mg (OH) ₂ particles, or a shaped body thereof, specifically, except for the above-mentioned raw magnesium oxide particles or Ca-added Mg (OH) ₂ particles, calcium oxide In addition to the content or calcination temperature, due to the calcination environment, calcination time, type and amount of additives such as lubricating materials, the size or shape of the calcined formed body, the aggregation of raw material magnesium oxide particles or Ca-added Mg (OH) ₂ particles The presence or absence of calcium oxide in the vicinity of the surface of the magnesium oxide particles, or the time and extent of the precipitation will vary. Therefore, in order to form the magnesium oxide particles or Ca-added Mg (OH) ₂ particles to form magnesium oxide particles, and to precipitate calcium oxide near the surface of the magnesium oxide particles, a calcium oxide-containing layer must be adjusted. Wait for the balance of calcination conditions.

When the catalyst carrier of the present invention is used, for example, when producing a synthetic gas production catalyst, at least one metal of ruthenium (Ru) and rhodium (Rh) may be supported on the catalyst carrier of the present invention. When manufacturing a synthetic gas manufacturing catalyst, Ru or Rh may be supported. However, the supported catalyst metal may use the catalyst, and other metals such as Ni, Ir, and Os may be appropriately selected according to the reaction to be performed. In the case of a catalyst, carbon precipitation can be effectively suppressed during the reaction.

The carrying amount of the catalyst metal is generally 200 to 2000 mass ppm in terms of metal, relative to the catalyst carrier of the present invention, but the reaction can be adjusted appropriately according to the implementation. The loading of the catalyst metal can generally be obtained by an ICP emission analysis device. Specifically, the catalyst sample is dissolved in aqua regia and quantified by irradiating a specific measurement wavelength.

The specific surface area of the catalyst carrier of the present invention, preferably 0.1m ² /g~1.0m ² / g. The "specific surface area" herein refers to the BET specific surface area calculated from the adsorption amount of nitrogen gas using a BET adsorption isotherm. For example, a specific surface area measuring device (product name "AUTOSORB-1", Yuasa Ionics Corporation) is used. System), using liquid nitrogen, measured by the multi-point method.

The depth of the catalyst metal carried by the catalyst carrier of the present invention on the surface of the catalyst carrier of the present invention is preferably within 10% of the particle size of the magnesium oxide particles (here, the "depth to the center"). . In other words, the region carrying the catalyst metal is preferably the region where the catalyst carrier of the present invention contains calcium oxide, that is, near the surface of the magnesium oxide particles.

The existence form of the catalyst metal carried by the catalyst carrier of the present invention is not particularly limited, but it is preferable that the vicinity of the surface of the magnesium oxide particles and the adjacent calcium oxide exist. The catalyst metal may cover all or part of the surface of the magnesium oxide particles, and the particles of the catalyst metal may be dispersed on the surface of the magnesium oxide particles. Alternatively, the catalyst metal may be partially localized on the surface of the magnesium oxide particles, and may be present, for example, in a recess on the surface of the magnesium oxide particles. Moreover, at least a part of the layered or particulate catalyst metal may cover the calcium oxide layer, or the layered or particulate catalyst metal may be alternately adjacent to the layered or particulate calcium oxide.

The method for supporting the catalyst metal on the catalyst carrier of the present invention is to spray the aqueous solution of the catalyst metal on the catalyst carrier of the present invention. An aqueous solution of a catalyst metal is obtained by dissolving an inorganic acid salt such as a nitrate or chloride of the metal or an organic acid salt such as an acetate in water. The amount of the sprayed aqueous solution is preferably, for example, 1.0 to 1.3 times the mass of water absorbed by the catalyst carrier. The water absorption of the catalyst carrier can be obtained by the Incipient-wetness method. This is a method of measuring the dripping amount of pure water with a small pipette or burette until the catalyst carrier is wetted.

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

By drying and calcining the catalyst carrier of the present invention carrying the catalyst metal, a desired catalyst can be obtained. The conditions for drying or calcining are not particularly limited. For example, the drying temperature is 50 to 150 ° C, the drying time is 1 to 3 hours, the calcination temperature is 300 to 500 ° C, and the calcining hour is about 1 to 5 hours.

    [Example]    

The following description uses examples to further understand the present invention. Most of the following examples are examples of manufacturing the catalyst carrier of the present invention, and when using this method to manufacture synthetic catalysts, the use of the catalyst carrier of the present invention is not limited to the synthesis of catalysts. The examples do not limit the invention. In the following, "wt%" and "wtppm" are used as a unit for indicating the concentration or content rate of a component, but the values expressed in these units are the same as those for "mass%" and "mass ppm".

    <Example 1>    

The powder (raw magnesium oxide particles) containing magnesium oxide (MgO) with a purity of 98.7 wt% of calcium oxide (CaO) converted to Ca in an amount of 0.3 wt% is mixed with carbon as a lubricating material in an amount of 3.0 wt% with respect to MgO powder. To form cylindrical particles with a diameter of 1/4 inch. The formed particles were calcined in air at 1180 ° C for 3 hours (hours) to obtain a catalyst carrier. The BET specific surface area of the obtained catalyst carrier was 0.10 m ² / g.

The obtained catalyst carrier was analyzed by ICP emission analysis (hereinafter simply referred to as "ICP"), and the catalyst carrier contained CaO in an amount of 0.3 wt% in terms of Ca. Furthermore, from the results of EPMA analysis, it was confirmed that Ca was not present inside the catalyst carrier, and that Ca existed only near the surface of the MgO particles. In addition, the obtained MgO particles constituting the catalyst carrier are significantly larger than the raw material magnesium oxide particles. Therefore, it is considered that the raw MgO particles are aggregated to form MgO particles, and CaO contained in the raw MgO particles is precipitated near the surface of the MgO particles. The EPMA analysis results of the cross section of the catalyst carrier are shown in Figure 4. In addition, the quantitative results obtained by converting the mol% of each element of the obtained catalyst carrier by EPMA analysis are shown in Table 1. The analysis points P1 to P10 are indicated by arrows in FIG. 4.

The obtained catalyst carrier is composed of spherical or peanut-shaped particles, as shown in FIG. 4. In addition, a part of the surface of the MgO particles of each of the catalyst carrier particles is covered with a layer containing CaO (CaO-containing layer), and CaO is present in a recess (depression) on the surface of the MgO particles. In addition, these CaO exist on the surface of the self-catalyst carrier (MgO particle), and the area is within 10% of the depth. When the calcium oxide content per unit surface area of the MgO particles is determined, the Ca conversion is 30 mg-Ca / m ² . As shown in FIG. 4 and Table 1, the central portion (analysis points P1 and P9) of the peanut-shaped particles contains only a small amount of Ca, and most of the Ca is contained at both end portions (analysis points P2 to P8 and P10).

Next, with respect to the obtained catalyst carrier, an aqueous solution of Ruthenium (III) nitrosyl nitrate containing 0.5 wt% of Ru was sprayed with 0.15cc (water absorption of the catalyst carrier) relative to 1.0 g of the catalyst carrier. 1.0 times), Ru was supported on a catalyst carrier. The catalyst carrier holding Ru thus obtained was dried in the air at 120 ° C for 2.5 hours in an oven, and calcined in an electric furnace at 400 ° C for 2.0 hours in the air to obtain a catalyst.

The obtained catalyst contained Ru in an amount of 750 wtppm relative to the catalyst, and its BET specific surface area was 0.10 m ² / g. The obtained catalyst was subjected to EPMA analysis in the same manner as the catalyst carrier. The catalyst EPMA analysis results are shown in Figure 5. Table 2 shows the quantitative results of the obtained catalysts in terms of mol% conversion of each element analyzed by EPMA. The analysis points P1 to P11 are indicated by arrows in FIG. 5.

As shown in FIG. 5, in the obtained catalyst, Ru is present in a region close to the surface of the catalyst particle, that is, a region within 10% of the depth from the surface of the catalyst. Since the positions of Ru and Ca overlap, CaO exists near this Ru. In addition, both Ru and CaO contained in the catalyst carrier exist near the surface of the MgO particles. As shown in FIG. 5 and Table 2, the central portion (analysis points P3 and P10) of the peanut-shaped particles contains only a small amount of Ca, and most of the Ca is contained at both end portions (analysis points P1 to P2, 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 H ₂ O / CO ₂ modification test of methane was performed. In addition, this reactor has a structure in which a raw material gas is introduced from 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 having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/0) was passed through the catalyst layer at 500 ° C. for 1 hour to react with the catalyst. Contacting for reduction treatment (activation of catalyst). Then, CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1 was processed under the conditions of a gas pressure of 1471 kPaG at the exit of the catalyst layer, a gas temperature of 850 ° C at the exit of the catalyst layer, and GHSV of methane basis = 2,500 / hour. 2.5: 1.5 raw material gas.

Results The conversion rate of CH ₄ after 5 hours from the start of the reaction was 92.5% (the equilibrium conversion rate of CH ₄ under the experimental conditions was 92.5%), and the conversion rate of CH ₄ after 1500 hours from the start of the reaction was 92.5% . In addition, after 1500 hours, when the catalyst was withdrawn in 4 equal divisions in the vertical direction, it was found that the carbon precipitated on the catalyst, and the carbon / catalyst was 0.2wt% (Top), 0.15 from the top in order. wt% (Md1), 0.1wt% (Md2), 0.10wt% (Btm). The conversion rate of CH ₄ is defined by the following formula.

CH ₄ conversion rate (%) = (AB) / A × 100

A: CH ₄ mole number in raw gas

B: Molar number of CH ₄ in the product (gas discharged from the catalyst layer)

The catalyst (catalyst before the raw material gas was ventilated) treated under the reduction treatment conditions described in Reaction Example 1 was subjected to S-TEM analysis. The results of elemental analysis by EDX are shown in FIG. 6. In FIG. 6, Ca, Mg, and Ru photographs are in order from the left side of the upper segment, and TEM photographs are in the lower segment.

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

    <Example 2>    

In a powder containing MgO having a purity of 98.7 wt% or more of CaO in terms of Ca of 0.3 wt%, carbon was mixed with 3.0 wt% of carbon relative to the MgO powder as a lubricating material to form a 1/4 inch diameter cylinder. particle. The formed particles were calcined in air at 1180 ° C for 3 hours to obtain a catalyst carrier. The BET specific surface area of the obtained catalyst carrier was 0.10 m ² / g.

When the obtained catalyst carrier was analyzed by ICP in the same manner as in Example 1, the catalyst carrier contained CaO in an amount of 0.3% by weight in terms of Ca. Furthermore, from the results of EPMA analysis, it was confirmed that Ca was not present inside the catalyst carrier, and that Ca existed only near the surface of the MgO particles. In addition, the obtained MgO particles constituting the catalyst carrier are significantly larger than the raw material magnesium oxide particles. Therefore, it is considered that the raw MgO particles are aggregated to form MgO particles, and CaO contained in the raw MgO particles is precipitated near the surface of the MgO particles.

The obtained catalyst carrier was in the same particle shape 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 concave portion on the surface of the MgO particles. In addition, these CaO exist on the surface of the self-catalyst carrier within a depth of 10%. When the amount of CaO per unit surface area of the MgO particles is determined, Ca is converted to 30 mg-Ca / m ² . In addition, the central portion of the peanut-shaped particles contains only a small amount of Ca, and almost all of the Ca is contained in both end portions.

Next, for the obtained catalyst carrier, an aqueous solution of ruthenium chloride hydrate (RuCl ₃ ) containing 0.55 wt% of Ru was sprayed with 0.17 cc (1.0 times the water absorption of the catalyst carrier) relative to 1.0 g of the catalyst carrier. Carry Ru on the catalyst carrier. The catalyst carrier holding Ru thus obtained was dried in the air at 120 ° C for 2.5 hours in an oven, and calcined in an 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 900 wtppm to the catalyst, and its BET specific surface area was 0.10 m ² / g. When the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ru existed near the surface of the catalyst particles, that is, a region within 10% of the depth of the catalyst surface. Therefore, it can be said that CaO exists near this Ru.

    <Reaction Example 2>    

50 cc of the catalyst prepared in Example 2 was filled in the same reactor as that of the user of Example 1, and a CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/3) in advance. , Contact with the catalyst for reduction. Then, CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1 was processed under the conditions of 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 basis = 2,500 / hour. 1: 0 raw material gas.

Results The conversion rate of CH ₄ after 5 hours from the start of the reaction was 54.8% (equal conversion of CH ₄ under the experimental conditions = 54.8%), and the conversion rate of CH ₄ was 54.8% after 300 hours from the start of the reaction. . In addition, after 1100 hours, the amount of carbon on the catalyst unloaded in 4 equal divisions as in Example 1 was 0.25 wt%, 0.1 wt%, 0.1 wt%, and 0.04 wt%, respectively, in that order from the top. In addition, when the catalyst treated under the pretreatment conditions described in Reaction Example 2 was analyzed in the same manner as in Example 1, it was confirmed that particulate Ru exists on the surface of the catalyst.

    <Example 3>    

In a powder containing MgO having a purity of 98.7 wt% or more of CaO in terms of Ca of 0.3 wt%, carbon was mixed with 3.0 wt% of carbon relative to the MgO powder as a lubricating material to form a 1/4 inch diameter cylinder. particle. The formed particles were calcined in air at 1180 ° C for 3 hours to obtain a catalyst carrier. The BET specific surface area of the obtained catalyst carrier was 0.10 m ² / g.

When the obtained catalyst carrier was analyzed by ICP in the same manner as in Example 1, the catalyst carrier contained CaO in an amount of 0.3% by weight in terms of Ca. Furthermore, from the results of EPMA analysis, it was confirmed that Ca was not present inside the catalyst carrier, and that Ca existed only near the surface of the MgO particles. In addition, the obtained MgO particles constituting the catalyst carrier are significantly larger than the raw material magnesium oxide particles. Therefore, it is considered that the raw MgO particles are aggregated to form MgO particles, and CaO contained in the raw MgO particles is precipitated near the surface of the MgO particles.

The obtained catalyst carrier was in the same particle shape 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 concave portion on the surface of the MgO particles. In addition, these CaO exist on the surface of the self-catalyst carrier within a depth of 10%. When the amount of CaO per unit surface area of the MgO particles is determined, Ca is converted into 30 mg-Ca / m ² . In addition, the central portion of the peanut-shaped particles contains only a small amount of Ca, and almost all of the Ca is contained in both end portions.

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

The obtained catalyst contained Ru in an amount of 300 wtppm relative to the catalyst, and its BET specific surface area was 0.10 m ² / g. When the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ru existed near the surface of the catalyst particles, that is, a region within 10% of the depth of the catalyst surface. Therefore, it can be said that CaO exists near this Ru.

    <Reaction Example 3>    

50 cc of the catalyst prepared in Example 3 was filled in the same reactor as that of the user of Example 1, and an H ₂ O / CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/6) in advance. , Contact with the catalyst for reduction. Then, CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1 was treated under the conditions of a gas pressure of 1471 kPaG at the exit of the catalyst layer, a temperature of 900 ° C at the exit of the catalyst layer, and GHSV of methane basis = 2,500 / hour. 3: 0.3 raw material gas.

Results The conversion rate of CH ₄ after 5 hours from the start of the reaction was 97.0% (the equilibrium conversion rate of CH ₄ under the experimental conditions was 97.0%), and the conversion rate of CH ₄ after 15,000 hours from the start of the reaction was 97.0%. . In addition, after 15,000 hours, the amount of carbon on the catalyst unloaded in 4 equal divisions as in Example 1 was 0.2 wt%, 0.05 wt%, 0.03 wt%, and 0.02 wt%, respectively, in that order from the top. Further, when the catalyst treated under the pretreatment conditions described in Reaction Example 3 was analyzed in the same manner as in Example 1, it was confirmed that Ru in particulate form was present on the surface of the catalyst.

    <Example 4>    

In a powder containing MgO having a purity of 98.7 wt% or more of CaO in terms of Ca of 0.3 wt%, carbon was mixed with 3.0 wt% of carbon relative to the MgO powder as a lubricating material to form a 1/4 inch diameter cylinder. particle. The formed particles were calcined in air at 1150 ° C for 3 hours to obtain a catalyst carrier. The BET specific surface area of the obtained catalyst carrier was 0.12 m ² / g.

When the obtained catalyst carrier was analyzed by ICP in the same manner as in Example 1, the catalyst carrier contained CaO in an amount of 0.3% by weight in terms of Ca. Furthermore, from the results of EPMA analysis, it was confirmed that Ca was not present inside the catalyst carrier, and that Ca existed only near the surface of the MgO particles. In addition, the obtained MgO particles constituting the catalyst carrier are significantly larger than the raw material magnesium oxide particles. Therefore, it is considered that the raw MgO particles aggregate to form MgO particles, and that the CaO contained in the raw MgO particles is precipitated near the surface of the MgO particles.

The obtained catalyst carrier was in the same particle shape 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 concave portion on the surface of the MgO particles. In addition, these CaO exist on the surface of the self-catalyst carrier within a depth of 10%. When the amount of CaO per unit surface area of the MgO particles is determined, the Ca conversion is 25 mg-Ca / m ² . In addition, the central portion of the peanut-shaped particles contains only a small amount of Ca, and almost all of the Ca is contained in both end portions.

Next, for the obtained catalyst carrier, an aqueous solution of rhodium acetate (Rh (CH ₃ COO) ₃ ) containing 0.3 wt% of Rh was sprayed with 0.15cc (1.0% of the water absorption of the catalyst carrier) relative to 1.0 g of the catalyst carrier. Times) so that Rh is supported on the catalyst carrier. The catalyst carrier carrying Rh thus obtained was dried in the air at 120 ° C for 2.5 hours in an oven, and calcined in an electric furnace at 650 ° C for 2.0 hours in the air to obtain a catalyst.

The obtained catalyst contained Rh in a ratio of 450 wtppm relative to the catalyst, and its BET specific surface area was 0.12 m ² / g. In addition, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Rh existed near the surface of the catalyst particles, that is, a region within 10% of the depth from the surface of the catalyst. Therefore, it can be said that CaO exists near this Rh.

    <Reaction Example 4>    

50 cc of the catalyst prepared in Example 4 was filled in the same reactor as that of the user of Example 1, and a CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/0) in advance. , Contact with the catalyst for reduction. Then, CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1 was processed under the conditions of 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 basis = 2,500 / hour. 1: 0 raw material gas.

Results The conversion rate of CH ₄ after 5 hours from the start of the reaction was 54.8% (equal conversion of CH ₄ under the experimental conditions = 54.8%), and the conversion rate of CH ₄ was 54.8% after 300 hours from the start of the reaction. . The conversion of CH ₄ after 800 hours had passed was 52.3%. In addition, after 800 hours, the carbon content on the catalyst unloaded in 4 equal divisions as in Example 1 was 0.15 wt%, 0.10 wt%, 0.05 wt%, and 0.03 wt%, respectively, in that order from the top. In addition, when the catalyst treated under the pretreatment conditions described in Reaction Example 4 was analyzed in the same manner as in Example 1, it was confirmed that Rh in particulate form was present on the catalyst surface.

    <Example 5>    

In a powder containing MgO having a purity of 98.7 wt% or more of CaO in terms of Ca of 0.3 wt%, carbon was mixed with 3.0 wt% of carbon relative to the MgO powder as a lubricating material to form a 1/4 inch diameter cylinder particle. The formed particles were calcined in air at 1200 ° C for 3 hours to obtain a catalyst carrier. The BET specific surface area of the obtained catalyst carrier was 0.08 m ² / g.

When the obtained catalyst carrier was analyzed by ICP in the same manner as in Example 1, the catalyst carrier contained CaO in an amount of 0.3% by weight in terms of Ca. In addition, from the results of EPMA analysis, it was confirmed that Ca was not present inside the catalyst carrier, and Ca existed only near the surface of the MgO particles. In addition, the obtained MgO particles constituting the catalyst carrier are significantly larger than the raw material magnesium oxide particles. Therefore, it is considered that the raw MgO particles are aggregated to form MgO particles, and CaO contained in the raw MgO particles is precipitated near the surface of the MgO particles.

The obtained catalyst carrier was in the same particle shape 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 concave portion on the surface of the MgO particles. In addition, these CaO exist on the surface of the self-catalyst carrier within a depth of 10%. When the amount of CaO per unit surface area of the MgO particles is determined, Ca is converted to 37.5 mg-Ca / m ² . In addition, the central portion of the peanut-shaped particles contains only a small amount of Ca, and almost all of the Ca is contained in both end portions.

Next, for the obtained catalyst carrier, an aqueous solution of ruthenium nitrite, nitrite, ruthenium nitrate containing 0.3 wt% of Ru was sprayed with 0.13cc (1.0 times the water absorption of the catalyst carrier) to 1.0 g of the catalyst carrier, and Ru was loaded. Hold on the catalyst carrier. The catalyst carrier holding Ru thus obtained was dried in the air at 120 ° C for 2.5 hours in an oven, and calcined in an electric furnace at 400 ° C for 2.0 hours in the air to obtain a catalyst.

The obtained catalyst contains Ru at a ratio of 1100 wtppm relative to the catalyst, and its BET specific surface area is 0.08 m ² / g. When the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ru existed near the surface of the catalyst particles, that is, a region within 10% of the depth of the catalyst surface. Therefore, it can be said that CaO exists near this Ru.

    <Reaction Example 5>    

50 cc of the catalyst prepared in Example 5 was filled in the same reactor as that of the user of Example 1, and a CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/3) in advance. , Contact with the catalyst for reduction. Then, CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1 was processed under the conditions that the gas pressure at the outlet of the catalyst layer was 1960 kPaG, the gas temperature at the outlet of the catalyst layer was 880 ° C, and the GHSV of the methane standard was 2,500 / hour. 1: 0 raw material gas.

Results The conversion rate of CH ₄ after 5 hours from the start of the reaction was 54.8% (equal conversion of CH ₄ under the experimental conditions = 54.8%), and the conversion rate of CH ₄ was 54.8% after 300 hours from the start of the reaction. . The conversion rate of CH ₄ after 700 hours had passed was 53.5%. After 700 hours, the amount of carbon on the catalyst unloaded in 4 equal divisions as in Example 1 was 0.15wt%, 0.04wt%, 0.03wt%, and 0.01wt%, respectively, in that order from the top. In addition, as in Example 1, when the catalyst treated under the pretreatment conditions described in Reaction Example 5 was analyzed, it was confirmed that Ru in particulate form was present on the surface of the catalyst.

    <Example 6>    

In a powder containing MgO having a purity of 98.7 wt% or more of CaO in terms of Ca of 0.3 wt%, carbon was mixed with 3.0 wt% of carbon relative to the MgO powder as a lubricating material to form a 1/4 inch diameter cylinder. particle. The formed particles were calcined in air at 1130 ° C for 3 hours to obtain a catalyst carrier. The BET specific surface area of the obtained catalyst carrier was 0.15 m ² / g.

When the obtained catalyst carrier was analyzed by ICP in the same manner as in Example 1, the catalyst carrier contained CaO in an amount of 0.3% by weight in terms of Ca. Furthermore, from the results of EPMA analysis, it was confirmed that Ca was not present inside the catalyst carrier, and that Ca existed only near the surface of the MgO particles. In addition, the obtained MgO particles constituting the catalyst carrier are significantly larger than the raw material magnesium oxide particles. Therefore, it is considered that the raw MgO particles are aggregated to form MgO particles, and CaO contained in the raw MgO particles is precipitated near the surface of the MgO particles.

The obtained catalyst carrier was in the same particle shape 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 concave portion on the surface of the MgO particles. In addition, these CaO exist on the surface of the self-catalyst carrier within a depth of 10%. When the amount of CaO per unit surface area of the MgO particles is determined, the Ca conversion is 20 mg-Ca / m ² . In addition, the central portion of the peanut-shaped particles contains only a small amount of Ca, and almost all of the Ca is contained in both end portions.

Next, with respect to the obtained catalyst carrier, an aqueous solution of ruthenium nitrate containing 0.6 wt% of Ru was sprayed with 0.18 cc (1.2 times the water absorption of the catalyst carrier) to 1.0 g of the catalyst carrier, so that Ru was supported on the catalyst. Media carrier. The catalyst carrier holding Ru thus obtained was dried in the air at 120 ° C for 2.5 hours in an oven, and calcined in an 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 relative to the catalyst, and its BET specific surface area was 0.15 m ² / g. When the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ru existed near the surface of the catalyst particles, that is, a region within 10% of the depth of the catalyst surface. Therefore, it can be said that CaO exists near this Ru.

    <Reaction Example 6>    

50 cc of the catalyst prepared in Example 6 was filled in the same reactor as the user of Example 1, and an H ₂ O / CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/2) in advance. , Contact with the catalyst for reduction. Then, CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1 was processed under the conditions that the gas pressure at the outlet of the catalyst layer was 1960 kPaG, the gas temperature at the outlet of the catalyst layer was 880 ° C, and the GHSV of the methane standard was 2,500 / hour. 0.4: 1 of raw material gas.

Results The conversion rate of CH ₄ after 5 hours from the start of the reaction was 66.7% (the equilibrium conversion rate of CH ₄ under the experimental conditions was 66.7%). The conversion rate of CH ₄ after 13,000 hours from the start of the reaction was 66.7%. . In addition, after 13,000 hours, the carbon content on the catalyst unloaded through 4 equal divisions as in Example 1 was 0.11 wt%, 0.05 wt%, 0.03 wt%, and 0.01 wt%, respectively, in that order from the top. In addition, when the catalyst treated under the pretreatment conditions described in Reaction Example 6 was analyzed in the same manner as in Example 1, it was confirmed that particulate Ru was present on the catalyst surface.

    <Example 7>    

When CaO content is 0.001wt% or less and the MgO powder with a purity of 99.9wt% or more is converted to Mg (OH) ₂ by boiling at 80 ° C, the Ca (OH) ₂ aqueous solution is dropped at the same time. After stirring, Ca-added Mg (OH) ₂ particles were obtained. This additive was mixed with 3.0 wt% of carbon as a lubricating material to form cylindrical particles having a diameter of 1/4 inch. The formed particles were calcined in air at 1180 ° C for 3 hours to obtain a catalyst carrier. The BET specific surface area of the obtained catalyst carrier was 0.10 m ² / g.

When the obtained catalyst carrier was analyzed by ICP in the same manner as in Example 1, the catalyst carrier contained 0.5 wt% CaO in terms of Ca. Furthermore, from the results of EPMA analysis, it was confirmed that Ca was not present inside the catalyst carrier, and that Ca existed only near the surface of the MgO particles. In addition, the obtained MgO particles constituting the catalyst carrier were significantly larger than 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 near the surface of the MgO particles.

The obtained catalyst carrier was in the same particle shape 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 concave portion on the surface of the MgO particles. In addition, these CaO exist on the surface of the self-catalyst carrier within a depth of 10% (that is, near the surface of the MgO particles). When the amount of CaO present on the surface of the MgO particles is determined, the Ca conversion is 50 mg-Ca / m ² . In addition, the central portion of the peanut-shaped particles contains only a small amount of Ca, and almost all of the Ca is contained in both end portions.

Next, for the obtained catalyst carrier, ruthenium nitrate aqueous solution containing 0.8 wt% of Ru was sprayed with 0.15 cc (1.0 times the water absorption of the catalyst carrier) with respect to 1.0 g of the catalyst carrier, to obtain a Ru carrier. Catalyst carrier. The catalyst carrier holding Ru thus obtained was dried in the air at 120 ° C for 2.5 hours in an oven, and calcined in an electric furnace at 400 ° C for 2.0 hours in the air to obtain a catalyst.

The obtained catalyst contained Ru in an amount of 1000 wtppm relative to the catalyst, and its BET specific surface area was 0.10 m ² / g. When the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ru existed near the surface of the catalyst particles, that is, a region within 10% of the depth of the catalyst surface. Therefore, it can be said that CaO exists near this Ru.

    <Reaction Example 7>    

50 cc of the catalyst prepared in Example 7 was filled in the same reactor as that of the user of Example 1, and an H ₂ O / CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/1) in advance. , Contact with the catalyst for reduction. Then, CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1 was processed under the conditions that the gas pressure at the outlet of the catalyst layer was 1960 kPaG, the gas temperature at the outlet of the catalyst layer was 880 ° C, and the GHSV of the methane standard was 2,500 / hour. 0.4: 1 of raw material gas.

Results The conversion rate of CH ₄ after 5 hours from the start of the reaction was 66.7% (the equilibrium conversion rate of CH ₄ under the experimental conditions was 66.7%). The conversion rate of CH ₄ after 13,000 hours from the start of the reaction was 66.7%. . In addition, after 13000 hours, the amount of carbon on the catalyst unloaded by four equal divisions as in Example 1 was 0.15 wt%, 0.08 wt%, 0.05 wt%, and 0.01 wt%, respectively, from the top. In addition, when the catalyst treated under the pretreatment conditions described in Reaction Example 7 was analyzed in the same manner as in Example 1, it was confirmed that Ru in particulate form was present on the surface of the catalyst.

    <Example 8>    

When the CaO content is 0.01 wt% or less and the MgO powder with a purity of 99.9 wt% or more is converted to Mg (OH) ₂ at 100 ° C, the Ca (OH) ₂ aqueous solution is dropped at the same time. After stirring, Ca-added Mg (OH) ₂ particles were obtained. In this additive, 3.0 wt% of carbon as a lubricating material was mixed to form 1/4 inch diameter particles. The formed particles were calcined in air at 1180 ° C for 3 hours to obtain a catalyst carrier. The BET specific surface area of the obtained catalyst carrier was 0.10 m ² / g.

When the obtained catalyst carrier was analyzed by ICP in the same manner as in Example 1, the catalyst carrier contained CaO in an amount of 1.4 wt% in terms of Ca conversion. Furthermore, from the results of EPMA analysis, it was confirmed that Ca was not present inside the catalyst carrier, and that Ca existed only near the surface of the MgO particles. In addition, the obtained MgO particles constituting the catalyst carrier were significantly larger than 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 near the surface of the MgO particles.

The obtained catalyst carrier was in the same particle shape 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 concave portion on the surface of the MgO particles. In addition, these CaO exist on the surface of the self-catalyst carrier within a depth of 10%. When the amount of CaO present on the surface of MgO particles is determined, it is 140 mg-Ca / m ^{2 in terms of} Ca. In addition, the central portion of the peanut-shaped particles contains only a small amount of Ca, and almost all of the Ca is contained in both end portions.

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

The obtained catalyst contains Ru at a ratio of 910wtppm relative to the catalyst, and its BET specific surface area is 0.10m ² / g. When the obtained catalyst was subjected to EPMA analysis in the same manner as in Example 1, Ru was carried near the surface of the catalyst particles. In addition, Ru exists in a region within 10% of the depth from the catalyst surface (that is, near the surface of the catalyst particles). Therefore, it can be said that CaO exists near this Ru.

    <Reaction Example 8>    

50 cc of the catalyst prepared in Example 8 was filled in the same reactor as that of the user of Example 1, and an H ₂ O / CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/1) in advance. , Contact with the catalyst for reduction. Then, CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1 was processed under the conditions that the gas pressure at the outlet of the catalyst layer was 1960 kPaG, the gas temperature at the outlet of the catalyst layer was 880 ° C, and the GHSV of the methane standard was 2,500 / hour. 0.4: 1 of raw material gas.

Results The conversion rate of CH ₄ after 5 hours from the start of the reaction (the equilibrium conversion rate of CH ₄ under the experimental conditions = 66.7%), and the conversion rate of CH ₄ after 9000 hours from the start of the reaction was 66.7%. . In addition, after 9000 hours have elapsed, the amount of carbon on the catalyst unloaded in 4 equal divisions as in Example 1 was 0.21 wt%, 0.15 wt%, 0.08 wt%, and 0.01 wt%, respectively, in that order from the top. In addition, when the catalyst treated under the pretreatment conditions described in Reaction Example 8 was analyzed in the same manner as in Example 1, it was confirmed that Ru in particulate form was present on the catalyst surface.

    <Example 9>    

In a powder containing MgO having a purity of 98.7 wt% or more of CaO in terms of Ca of 0.3 wt%, carbon was mixed with 3.0 wt% of carbon relative to the MgO powder as a lubricating material to form a 1/4 inch diameter cylinder. particle. The formed particles were calcined in air at 1150 ° C for 3 hours to obtain a catalyst carrier. The BET specific surface area of the obtained catalyst carrier was 0.12 m ² / g.

When the obtained catalyst carrier was analyzed by ICP in the same manner as in Example 1, the catalyst carrier contained CaO in an amount of 0.3% by weight in terms of Ca. Furthermore, from the results of EPMA analysis, it was confirmed that Ca was not present inside the catalyst carrier, and that Ca existed only near the surface of the MgO particles. In addition, the obtained MgO particles constituting the catalyst carrier are significantly larger than the raw material magnesium oxide particles. Therefore, it is considered that the raw MgO particles are aggregated to form MgO particles, and CaO contained in the raw MgO particles is precipitated near the surface of the MgO particles. In addition, the obtained catalyst carrier was in the same particle shape as in Example 1. Part of the surface of the MgO particles was covered with a layer containing CaO, and CaO was present in the concave portion on the surface of the MgO particles. In addition, these CaO exist on the surface of the self-catalyst carrier within a depth of 10%. When the amount of CaO present on the surface of the MgO particles is determined, the Ca conversion is 25 mg-Ca / m ² . In addition, the central portion of the peanut-shaped particles contains only a small amount of Ca, and almost all of the Ca is contained in both end portions.

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

The obtained catalyst contained Rh in a ratio of 1350 wtppm to the catalyst, and its BET specific surface area was 0.12 m ² / g. In addition, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Rh existed near the surface of the catalyst particles, that is, a region within 10% of the depth from the surface of the catalyst. Therefore, it can be said that CaO exists near this Rh.

    <Reaction Example 9>    

50 cc of the catalyst prepared in Example 9 was filled in the same reactor as that of the user of Example 1, and an H ₂ O / CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/0) in advance. , Contact with the catalyst for reduction. Then, CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1 was processed under the conditions that the gas pressure at the outlet of the catalyst layer was 1960 kPaG, the gas temperature at the outlet of the catalyst layer was 880 ° C, and the GHSV of the methane standard was 2,500 / hour. 0.4: 1 of raw material gas.

Results The conversion rate of CH ₄ after 5 hours from the start of the reaction (the equilibrium conversion rate of CH ₄ under the experimental conditions = 66.7%), and the conversion rate of CH ₄ after 8000 hours from the start of the reaction was 66.7%. . The conversion rate of CH ₄ after 8000 hours was 66.7%. In addition, after 8000 hours, the carbon content on the catalyst unloaded by four equal divisions as in Example 1 was 0.15 wt%, 0.07 wt%, 0.05 wt%, and 0.01 wt%, respectively, in that order from the top. In addition, when the catalyst treated under the pretreatment conditions described in Reaction Example 9 was analyzed in the same manner as in Example 1, it was confirmed that Rh in particulate form was present on the catalyst surface.

    <Example 10>    

When the CaO content is 0.001wt% or less and the MgO powder with a purity of 99.9wt% or more is converted to Ca by boiling at 100 ° C to form Mg (OH) ₂ , the Ca (OH) ₂ aqueous solution is dropped at the same time. After stirring, Ca-added Mg (OH) ₂ particles were obtained. In this additive, 3.0 wt% of carbon as a lubricating material was mixed to form 1/4 inch diameter particles. The formed particles were calcined in air at 1180 ° C for 3 hours to obtain a catalyst carrier. The BET specific surface area of the obtained catalyst carrier was 0.10 m ² / g.

When the obtained catalyst carrier was analyzed by ICP in the same manner as in Example 1, the catalyst carrier contained CaO at 0.01 wt% in terms of Ca. Furthermore, from the results of EPMA analysis, it was confirmed that Ca was not present inside the catalyst carrier, and that Ca existed only near the surface of the MgO particles. In addition, the obtained MgO particles constituting the catalyst carrier were significantly larger than 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 near the surface of the MgO particles. In addition, the obtained catalyst carrier was in the same particle shape as in Example 1. Part of the surface of the MgO particles was covered with a layer containing CaO, and CaO was present in the concave portion on the surface of the MgO particles. In addition, these CaO exist on the surface of the self-catalyst carrier within a depth of 10%. When the amount of CaO present on the surface of MgO particles is determined, it is converted to 1 mg-Ca / m ^{2 in terms of} Ca. In addition, the central portion of the peanut-shaped particles contains only a small amount of Ca, and almost all of the Ca is contained in both end portions.

Next, for the obtained catalyst carrier, a ruthenium nitrate aqueous solution containing 0.6 wt% of Ru was sprayed with 0.15 cc (1.0 times the water absorption of the catalyst carrier) with respect to 1.0 g of the catalyst carrier to obtain a Ru carrier. Catalyst carrier.

Next, the obtained catalyst carrier carrying Ru was dried in the air at 120 ° C for 2.5 hours in an oven, and then calcined in an 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 relative to the catalyst, and its BET specific surface area was 0.10 m ² / g. When the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ru was present near the surface of the catalyst particles. In addition, Ru exists in a region within 10% of the depth of the catalyst surface. Therefore, it can be said that CaO exists near this Ru.

    <Reaction Example 10>    

50 cc of the catalyst prepared in Example 10 was filled in the same reactor as that of the user of Example 1, and an H ₂ O / CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/1) in advance. , Contact with the catalyst for reduction. Then, CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1 was processed under the conditions that the gas pressure at the outlet of the catalyst layer was 1960 kPaG, the gas temperature at the outlet of the catalyst layer was 880 ° C, and the GHSV of the methane standard was 2,500 / hour. 0.4: 1 of raw material gas.

Results The conversion rate of CH ₄ after 5 hours from the start of the reaction was 66.7% (the equilibrium conversion rate of CH ₄ under the experimental conditions was 66.7%). Furthermore, the conversion rate of CH ₄ after 5000 hours from the start of the reaction was 66.7%. . In addition, after 5000 hours, the carbon content on the catalyst unloaded in 4 equal divisions as in Example 1 was 0.28 wt%, 0.17 wt%, 0.09 wt%, and 0.01 wt%, respectively, in that order from the top. In addition, when the catalyst treated under the pretreatment conditions described in Reaction Example 10 was analyzed in the same manner as in Example 1, it was confirmed that particulate Ru was present on the catalyst surface.

    <Example 11>    

In a powder containing MgO having a purity of 98.7 wt% or more of CaO in terms of Ca of 0.3 wt%, carbon was mixed with 3.0 wt% of carbon relative to the MgO powder as a lubricating material to form a 1/4 inch diameter cylinder. particle. The formed particles were calcined in the air at 1100 ° C for 3 hours to obtain a catalyst carrier. The BET specific surface area of the obtained catalyst carrier was 0.20 m ² / g.

When the obtained catalyst carrier was analyzed by ICP in the same manner as in Example 1, the catalyst carrier contained CaO in an amount of 0.3% by weight in terms of Ca. Furthermore, from the results of EPMA analysis, it was confirmed that Ca was not present inside the catalyst carrier, and that Ca existed only near the surface of the MgO particles. In addition, the obtained MgO particles constituting the catalyst carrier are significantly larger than the raw material magnesium oxide particles. Therefore, it is considered that the raw MgO particles aggregate to form MgO particles, and CaO contained in the raw MgO particles is precipitated on the surface of the MgO particles. In addition, the obtained catalyst carrier was in the same particle shape as in Example 1. Part of the surface of the MgO particles was covered with a layer containing CaO, and CaO was present in the concave portion on the surface of the MgO particles. In addition, these CaO exist on the surface of the self-catalyst carrier within a depth of 10%. When the amount of CaO present on the surface of MgO particles is determined, it is 15 mg-Ca / m ^{2 in terms of} Ca. In addition, the central portion of the peanut-shaped particles contains only a small amount of Ca, and almost all of the Ca is contained in both end portions.

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

The obtained catalyst contains Ni at a ratio of 10,000 wtppm to the catalyst, and has a BET specific surface area of 0.20 m ² / g. When the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ni was present near the surface of the catalyst particles, that is, Ca and Ni existed in a region within 10% of the depth from the surface of the catalyst.

    <Example 12>    

In a powder containing MgO having a purity of 98.7 wt% or more of CaO in terms of Ca of 0.3 wt%, carbon was mixed with 3.0 wt% of carbon relative to the MgO powder as a lubricating material to form a 1/4 inch diameter cylinder. particle. The formed particles were calcined in the air at 1100 ° C for 3 hours to obtain a catalyst carrier. The BET specific surface area of the obtained catalyst carrier was 0.10 m ² / g.

When the obtained catalyst carrier was analyzed by ICP in the same manner as in Example 1, the catalyst carrier contained CaO in an amount of 0.3% by weight in terms of Ca. Furthermore, from the results of EPMA analysis, it was confirmed that Ca was not present inside the catalyst carrier, and that Ca existed only near the surface of the MgO particles. In addition, the obtained MgO particles constituting the catalyst carrier are significantly larger than the raw material magnesium oxide particles. Therefore, it is considered that the raw MgO particles are aggregated to form MgO particles, and CaO contained in the raw MgO particles is precipitated near the surface of the MgO particles.

The obtained catalyst carrier was in the same particle shape 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 concave portion on the surface of the MgO particles. In addition, these CaO exist on the surface of the self-catalyst carrier within a depth of 10%. When the amount of CaO present on the surface of MgO particles is determined, it is 15 mg-Ca / m ^{2 in terms of} Ca. In addition, the central portion of the peanut-shaped particles contains only a small amount of Ca, and almost all of the Ca is contained in both end portions.

Next, for the obtained catalyst carrier, an iridium chloride aqueous solution containing 02.7 wt% of Ir was sprayed with 0.15cc (1.0 times the water absorption of the catalyst carrier) relative to 1.0 g of the catalyst carrier, so that Ir was supported on Catalyst carrier. The catalyst carrier carrying Ir thus obtained was dried in the air at 120 ° C. for 2.5 hours in an oven, and then calcined in an electric furnace at 650 ° C. for 2.0 hours in the air to obtain a catalyst.

When the obtained catalyst contained Ir at a ratio of 3500 wtppm to the catalyst, its BET specific surface area was 0.20 m ² / g. In addition, when the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ca and Ir existed near the surface of the catalyst particles, that is, a region within 10% of the depth from the surface of the catalyst.

    <Example 13>    

In a powder containing MgO having a purity of 98.7 wt% or more of CaO in terms of Ca of 0.3 wt%, carbon was mixed with 3.0 wt% of carbon relative to the MgO powder as a lubricating material to form a 1/4 inch diameter cylinder particle. The formed particles were calcined in the air at 1100 ° C for 3 hours to obtain a catalyst carrier. The BET specific surface area of the obtained catalyst carrier was 0.20 m ² / g.

When the obtained catalyst carrier was analyzed by ICP in the same manner as in Example 1, the catalyst carrier contained CaO in an amount of 0.3% by weight in terms of Ca. From the results of EPMA analysis, it was confirmed that Ca was not present in the catalyst carrier, and that Ca was present only near the surface of the MgO particles. In addition, the obtained MgO particles constituting the catalyst carrier are significantly larger than the raw material magnesium oxide particles. Therefore, it is considered that the raw MgO particles are aggregated to form MgO particles, and CaO contained in the raw MgO particles is precipitated near the surface of the MgO particles.

The obtained catalyst carrier was in the same particle shape 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 concave portion on the surface of the MgO particles. In addition, these CaO exist on the surface of the self-catalyst carrier within a depth of 10%. In addition, when the amount of CaO present on the surface of the MgO particles is determined, it is 15 mg-Ca / m ^{2 in terms of} Ca. In addition, the central portion of the peanut-shaped particles contains only a small amount of Ca, and almost all of the Ca is contained in both end portions.

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

When the obtained catalyst contained Os at a ratio of 3500 wtppm relative to the catalyst, the BET specific surface area was 0.20 m ² / g. Moreover, when the obtained catalyst was subjected to EPMA analysis in the same manner as in Example 1, Ca and Os existed near the surface of the catalyst particles, that is, a region within 10% of the depth from the surface of the catalyst.

    <Comparative example 1>    

In a powder containing MgO having a purity of 98.7 wt% or more of CaO in terms of Ca of 0.3 wt%, carbon was mixed with 3.0 wt% of carbon relative to the MgO powder as a lubricating material to form a 1/4 inch diameter cylinder. particle. The formed particles were calcined at 600 ° C for 3 hours in the air to obtain a catalyst carrier.

When the obtained catalyst carrier was analyzed by ICP in the same manner as in Example 1, the catalyst carrier contained CaO in an amount of 0.3% by weight in terms of Ca. The EPMA analysis results of the cross section of the catalyst carrier are shown in Figure 7. The obtained catalyst carrier was particulate as shown in FIG. 7, and CaO was uniformly distributed inside the MgO particles. It was not confirmed that the precipitates were deposited near the surface of the MgO particles, and CaO did not exist near the surface of the MgO.

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

The obtained catalyst contained Rh in a proportion of 15000 wtppm relative to the catalyst, and its BET specific surface area was 32.0 m ² / g. Regarding the obtained catalyst, when the EPMA analysis was performed in the same manner as in Example 1, Rh was carried on the surface of the catalyst particles. In addition, Rh exists within 10% of the surface depth of the catalyst. In addition, Ca was uniformly distributed inside the MgO particles, no precipitation was confirmed on the surface, and no CaO-containing layer was present on the surface. No Ca was present near Rh.

    <Comparative Reaction Example 1>    

50 cc of the catalyst prepared in Comparative Example 1 was filled in the same reactor as that of the user of Example 1, and a CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/3) in advance. , Contact with the catalyst for reduction. Then, CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1 was processed under the conditions that the gas pressure at the outlet of the catalyst layer was 1960 kPaG, the gas temperature at the outlet of the catalyst layer was 880 ° C, and the GHSV of the methane standard was 2,500 / hour. 1: 0 raw material gas. The conversion rate of CH ₄ after 5 hours from the start of the reaction was 54.8% (equal conversion rate of CH ₄ under experimental conditions = 54.8%), and the conversion rate of CH ₄ after 30 hours was 47.3%. After 30 hours, the amount of carbon on the catalyst unloaded in 4 equal divisions as in Example 1 was 3.2 wt%, 2.3 wt%, 2.2 wt%, and 2.1 wt%, respectively, in that order from the top. In addition, as in Example 1, when the catalyst treated under the pretreatment conditions described in Comparative Reaction Example 1 was analyzed, it was confirmed that Rh particles existed on the surface of the catalyst.

    <Comparative example 2>    

A commercially available silica alumina molded body having a CaO content of 0.001 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 carrier was analyzed by ICP in the same manner as in Example 1, the CaO content of the catalyst carrier was 0.01% by weight or less in terms of Ca conversion. In the obtained catalyst carrier, Ca was not present on the surface.

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

The obtained catalyst contained Rh in a proportion of 850 wtppm relative to the catalyst, and its BET specific surface area was 24.0 m ² / g. When the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ca was not present near Rh.

    <Comparative Reaction Example 2>    

50 cc of the catalyst prepared in Comparative Example 2 was filled in the same reactor as that of the user of Example 1, and a CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/0) in advance. , Contact with the catalyst for reduction. Then, CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1 was processed under the conditions that the gas pressure at the outlet of the catalyst layer was 1960 kPaG, the gas temperature at the outlet of the catalyst layer was 880 ° C, and the GHSV of the methane standard was 2,500 / hour. 1: 0 raw material gas. The conversion rate of CH ₄ after 5 hours from the start of the reaction was 35.3% (equal conversion rate of CH ₄ under experimental conditions = 54.8%), and the conversion rate of CH ₄ after 20 hours was 28.2%. After 20 hours, the amount of carbon on the catalyst unloaded through four divisions in the same manner as in Example 1 was 1.8 wt%, 1.3 wt%, 0.8 wt%, and 0.5 wt%, respectively, from the top. In addition, as in 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 surface of the catalyst.

    <Comparative example 3>    

A commercially available ZnO molded body having a CaO content of 0.001 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 carrier was analyzed by ICP in the same manner as in Example 1, the CaO content of the catalyst carrier was 0.01% by weight or less in terms of Ca conversion. In the obtained catalyst carrier, Ca was not present on the surface.

Next, for the obtained catalyst carrier, 0.37 wt% of rhodium acetate aqueous solution containing 0.37 wt% of the catalyst carrier was sprayed with 0.37cc (1.0 times the water absorption of the catalyst carrier) with respect to 1.0 g of the catalyst carrier to obtain a Rh carrier. Catalyst carrier ZnO. The BET specific surface area of the obtained catalyst carrier carrying Rh was 1.5 m ² / g. In addition, when the obtained catalyst carrier carrying Rh was subjected to EPMA analysis in the same manner as in Example 1, Ca was not biased to the surface.

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

    <Comparative Reaction Example 3>    

50 cc of the catalyst prepared in Comparative Example 3 was filled in the same reactor as that of the user of Example 1, and a CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/2) in advance. , Contact with the catalyst for reduction. Then, CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1 was processed under the conditions that the gas pressure at the outlet of the catalyst layer was 1960 kPaG, the gas temperature at the outlet of the catalyst layer was 880 ° C, and the GHSV of the methane standard was 2,500 / hour. 1: 0 raw material gas. The conversion rate of CH ₄ after 5 hours from the start of the reaction was 15.8% (equilibrium conversion rate of CH ₄ under the experimental conditions = 54.8%), and the conversion rate of CH ₄ was 10.2% after 40 hours. After 40 hours, the amount of carbon on the catalyst unloaded through four divisions in the same manner as in Example 1 was 5.5 wt%, 5.1 wt%, 3.2 wt%, and 2.1 wt%, respectively, in that order from the top. When analyzed in the same manner as in Example 1, it was confirmed that Rh particles were present on the catalyst surface.

    <Comparative Example 4>    

A commercially available CaO molded body was calcined at 950 ° C for 3 hours in the air to obtain a catalyst carrier. The obtained catalyst carrier was subjected to ICP analysis in the same manner as in Example 1. The constituent component of the obtained catalyst carrier itself is CaO.

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

When the obtained catalyst contained Rh at a ratio of 780 wtppm relative to the catalyst, its BET specific surface area was 8.90 m ² / g. When the obtained catalyst was subjected to EPMA analysis in the same manner as in Example 1, Rh was carried on the surface of the carrier CaO.

    <Comparative Reaction Example 4>    

50 cc of the catalyst prepared in Comparative Example 4 was filled in the same reactor as that of the user of Example 1, and a CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/5) in advance. , Contact with the catalyst for reduction. Then, CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1 was processed under the conditions of a gas pressure of 1960 kPaG at the exit of the catalyst layer, a temperature of 880 ° C at the exit of the catalyst layer, and GHSV of methane basis = 2,500 / hour. 1: 0 raw material gas. The conversion rate of CH ₄ after 5 hours from the start of the reaction was 25.3% (equilibrium conversion rate of CH ₄ under experimental conditions = 54.8%), and the conversion rate of CH ₄ after 70 hours was 18.2%. In addition, after 70 hours, the amount of carbon on the catalyst unloaded through four divisions in the same manner as in Example 1 was 17.4% by weight, 10.3% by weight, 5.1% by weight, and 4.7% by weight in order from the top. In addition, when the catalyst treated under the processing conditions described in Comparative Reaction Example 4 was analyzed in the same manner as in Example 1, 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 0.001 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 carrier was analyzed by ICP in the same manner as in Example 1, the CaO content of the catalyst carrier was 0.01% by weight or less in terms of Ca conversion. In the obtained catalyst carrier, Ca was not present on the surface.

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

The obtained catalyst contained Rh in a ratio of 900 wtppm relative to the catalyst, and its BET specific surface area was 4.20 m ² / g. In addition, 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 surface of the catalyst.

    <Comparative Reaction Example 5>    

50 cc of the catalyst prepared in Comparative Example 5 was filled in the same reactor as that of the user of Example 1, and a CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/3) in advance. , Contact with the catalyst for reduction. Then, CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1 was processed under the conditions that the gas pressure at the outlet of the catalyst layer was 1960 kPaG, the gas temperature at the outlet of the catalyst layer was 880 ° C, and the GHSV of the methane standard was 2,500 / hour. 1: 0 raw material gas. The conversion rate of CH ₄ after 5 hours from the start of the reaction was 37.8% (equal conversion rate of CH ₄ under the experimental conditions = 54.8%), and the conversion rate of CH ₄ after 10 hours was 30.2%. After 10 hours, the amount of carbon on the catalyst unloaded through four divisions in the same manner as in Example 1 was 1.5 wt%, 2.3 wt%, 3.2 wt%, and 3.2 wt%, respectively, in that order from the top. In addition, as in Example 1, when the catalyst treated under the previous processing conditions described in Comparative Reaction Example 5 was analyzed, it was confirmed that Rh particles existed on the surface of the catalyst.

    <Comparative Example 6>    

A commercially available Al ₂ O ₃ compact having a CaO content of 0.001 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 carrier was analyzed by ICP in the same manner as in Example 1, the CaO content of the catalyst carrier was 0.01% by weight or less in terms of Ca conversion. In the obtained catalyst carrier, Ca was not present on the surface.

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

When the obtained catalyst contained Rh at a ratio of 1200 wtppm to the catalyst, the BET specific surface area was 110.0 m ² / g. When the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ca was not selectively present near Rh.

    <Comparative Reaction Example 6>    

50 cc of the catalyst prepared in Comparative Example 9 was filled in the same reactor as that of the user of Example 1, and a CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/1) in advance. , Contact with the catalyst for reduction. Then, CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1 was processed under the conditions that the gas pressure at the outlet of the catalyst layer was 1960 kPaG, the gas temperature at the outlet of the catalyst layer was 880 ° C, and the GHSV of the methane standard was 2,500 / hour. 1: 0 raw material gas. The conversion rate of CH ₄ after 5 hours from the start of the reaction was 54.8% (equal conversion rate of CH ₄ under experimental conditions = 54.8%), and the conversion rate of CH ₄ after 50 hours was 51.2%. After 50 hours, the amount of carbon on the catalyst unloaded through four divisions in the same manner as in Example 1 was sequentially 16.1 wt%, 10.3 wt%, 5.2 wt%, and 4.8 wt%, respectively, from the top. When analyzed in the same manner as in Example 1, it was confirmed that Rh particles were present on the catalyst surface.

    <Comparative Example 7>    

For MgO powder having a CaO content of 0.001 wt% or less and a purity of 99.9 wt% or more in terms of Ca conversion, 3.0 wt% of carbon relative to the MgO powder was mixed as a lubricating material to form cylindrical particles of 1/4 inch diameter. The formed particles were calcined in the air at 1100 ° C for 3 hours to obtain a catalyst carrier. When the obtained catalyst carrier was analyzed by ICP in the same manner as in Example 1, the CaO content of the catalyst carrier was 0.001 wt% or less in terms of Ca, and its BET specific surface area was 0.2 m ² / g. In addition, it was not confirmed that CaO precipitated on the surface, and CaO did not exist on the surface of the catalyst carrier.

Secondly, for the obtained catalyst carrier, an aqueous rhodium acetate solution containing 0.73% by weight of Rh was sprayed with 0.18cc (1.2 times the mass of the water absorption of the catalyst carrier) relative to 1.0 g of the catalyst carrier to obtain a holding Rh. Catalyst carrier. The catalyst carrier carrying Rh thus obtained was dried in the air at 120 ° C for 2.5 hours in an oven, and then calcined in the air at 950 ° C for 2.0 hours in an electric furnace to obtain a catalyst.

The obtained catalyst contained Rh in a proportion of 1300 wtppm relative to the catalyst, and its BET specific surface area was 0.20 m ² / g. When the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ca was not present near Rh.

    <Comparative Reaction Example 7>    

50 cc of the catalyst prepared in Comparative Example 7 was filled in the same reactor as that of the user of Example 1, and a CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/3) in advance. After contacting with the catalyst for reduction treatment, CH ₄ : CO ₂ : H ₂ O is treated under the conditions of a gas pressure at the outlet of the catalyst layer of 1960kPaG, a gas temperature at the outlet of the catalyst layer of 880 ° C, and a GHSV of methane basis = 2,500 / hour. (Mole ratio) = 1: 1 raw material gas.

Results The conversion rate of CH ₄ after 5 hours from the start of the reaction was 54.8% (balanced conversion rate of CH ₄ under experimental conditions = 54.8%), and the conversion rate of CH ₄ was 52.3% after 70 hours. After 70 hours, the amount of carbon on the catalyst unloaded in four divisions in the same manner as in Example 1 was 6.5%, 3.5%, 3.2%, and 2.4% by weight, respectively, in that order from the top. When analyzed in the same manner as in Example 1, it was confirmed that Rh particles were present on the catalyst surface.

    <Comparative Example 8>    

For powders of MgO having a CaO content of 0.001 wt% or more with a Ca conversion of 0.001 wt% or less, 3.0 wt% of carbon relative to the MgO powder was mixed as a lubricating material to form cylindrical particles of 1/4 inch diameter. The formed particles were calcined in air at 1100 ° C for 3 hours to obtain a catalyst carrier. When the obtained catalyst carrier was analyzed by ICP in the same manner as in Example 1, the CaO content of the catalyst carrier was 0.001 wt% or less in terms of Ca conversion. In the obtained catalyst carrier, it was not confirmed that CaO precipitated on the surface, and CaO did not exist on the surface of the catalyst carrier.

Next, for the obtained catalyst carrier, an aqueous rhodium acetate solution containing 0.87 wt% of Rh was sprayed with 0.15cc (1.0 times the water absorption of the catalyst carrier) with respect to 1.0 g of the catalyst carrier to obtain a Rh carrier. Catalyst carrier. The catalyst carrier containing Rh thus obtained was dried in the air at 120 ° C for 2.5 hours in an oven, and then a 0.5 wt% Pt chloroplatinic acid aqueous solution was sprayed on 1.0 g of the carrier. 0.15cc (1.0 times the water absorption of 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 contains Rh in a proportion of 1300wtppm relative to the catalyst, and Pt in a proportion of 750wtppm relative to the catalyst, and has a BET specific surface area of 0.20m ² / g. When the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ca was not present near Rh and Pt.

    <Comparative Reaction Example 8>    

50 cc of the catalyst prepared in Comparative Example 11 was filled in the same reactor as that of the user of Example 1, and a CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/3) in advance. , Contact with the catalyst for reduction. Then, CH ₄ : CO ₂ : H ₂ O (molar ratio) = 1 was processed under the conditions that the gas pressure at the outlet of the catalyst layer was 1960 kPaG, the gas temperature at the outlet of the catalyst layer was 880 ° C, and the GHSV of the methane standard was 2,500 / hour. 1: 0 raw material gas. The conversion rate of CH ₄ after 5 hours from the start of the reaction was 54.8% (equilibrium conversion rate of CH ₄ under experimental conditions = 54.8%), and the conversion rate of CH ₄ after 15 hours was 54.8%. After 15 hours, the amount of carbon on the catalyst unloaded through four divisions in the same manner as in Example 1 was 1.6% by weight, 2.3% by weight, 3.2% by weight, and 2.7% by weight in this order. In addition, when the catalyst treated under the processing conditions described in Comparative Reaction Example 8 in the same manner as in Example 1 was analyzed, it was confirmed that Rh particles were present on the surface of the catalyst.

    <Comparative Example 9>    

For MgO powder with CaO content of 0.001wt% or less in terms of Ca and purity of 99.9wt% or more, 3.0% by weight of carbon relative to MgO powder is used as a lubricating material to form 1/4 inch diameter cylindrical particles . The formed particles were sprayed with a lanthanum nitrate aqueous solution containing 5.1 wt% of La to carry La, and then calcined at 1100 ° C for 3 hours in the air to obtain a catalyst carrier. When the obtained catalyst carrier was analyzed by ICP as in Example 1, the La content of the catalyst carrier was 1.5 wt% or less, and the CaO content was 0.001 wt% or less in terms of Ca conversion. In the obtained catalyst carrier, it was not confirmed that CaO precipitated on the surface, and CaO did not exist on the surface of the catalyst carrier.

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

The obtained catalyst contained Rh in a proportion of 1300 wtppm relative to the catalyst, and its BET specific surface area was 0.20 m ² / g. When the obtained catalyst was analyzed by EPMA in the same manner as in Example 1, Ca and La did not exist near Rh.

    <Comparative Reaction Example 9>    

50 cc of the catalyst prepared in Comparative Example 12 was filled in the same reactor as that of the user of Example 1, and a CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/0) in advance. After contacting with the catalyst for reduction treatment, CH ₄ : CO ₂ : H ₂ O is treated under the conditions of a gas pressure at the outlet of the catalyst layer of 1960kPaG, a gas temperature at the outlet of the catalyst layer of 880 ° C, and a GHSV of methane basis = 2,500 / hour. (Mole ratio) = 1: 1 raw material gas. The conversion rate of CH ₄ after 5 hours from the start of the reaction was 54.8% (equal conversion rate of CH ₄ under experimental conditions = 54.8%), and the conversion rate of CH ₄ after 50 hours was 54.8%. After 50 hours, the amount of carbon on the catalyst unloaded through four divisions in the same manner as in Example 1 was 7.2% by weight, 5.1% by weight, 2.1% by weight, and 1.2% by weight in order from the top. In addition, when the catalyst treated under the pretreatment conditions described in Comparative Reaction Example 9 was analyzed in the same manner as in Example 1, it was confirmed that Rh particles were present on the catalyst surface.

    <Comparative Example 10>    

When the CaO content is 0.001wt% or less and the MgO powder with a purity of 99.9wt% or more is converted to Ca by boiling at 100 ° C to form Mg (OH) ₂ , the Ca (OH) ₂ aqueous solution is dropped. After stirring, Ca-added Mg (OH) ₂ particles were obtained. This additive was mixed with 3.0 wt% of carbon as a lubricating material to form cylindrical particles having a diameter of 1/4 inch. The formed particles were calcined in air at 1180 ° C for 3 hours to obtain a catalyst carrier. The BET specific surface area of the obtained catalyst carrier was 0.10 m ² / g.

When the obtained catalyst carrier was analyzed by ICP in the same manner as in Example 1, the CaO content of the catalyst carrier was 1.8 wt%. Furthermore, from the results of EPMA analysis, it was confirmed that Ca was not present inside the catalyst carrier, and that Ca existed only near the surface of the MgO particles. In addition, the obtained MgO particles constituting the catalyst carrier were significantly larger than 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 near the surface of the MgO particles. In addition, the obtained catalyst carrier was in the same particle shape as in Example 1. Part of the surface of the MgO particles was covered with a layer containing CaO, and CaO was present in the concave portion on the surface of the MgO particles. In addition, these CaO exist on the surface of the self-catalyst carrier within a depth of 10%. In addition, when the amount of CaO present on the surface of the MgO particles is determined, it is 80 mg-Ca / m ^{2 in terms of} Ca. In addition, the central portion of the peanut-shaped particles contains only a small amount of Ca, and almost all of the Ca is contained in both end portions.

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

When the obtained catalyst contained Rh at a ratio of 1300 wtppm relative to the catalyst, the BET specific surface area was 0.10 m ² / g. When the obtained catalyst was subjected to EPMA analysis in the same manner as in Example 1, Rh was carried on the surface of the catalyst particles. Moreover, Rh exists in a region within 10% of the depth from the catalyst surface. Therefore, CaO exists near this Rh.

    <Comparative Reaction Example 10>    

50 cc of the catalyst prepared in Comparative Example 10 was filled in the same reactor as that of the user of Example 1, and a CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/0) in advance. After contacting with the catalyst for reduction treatment, CH ₄ : CO ₂ : H ₂ O is treated under the conditions of a gas pressure at the outlet of the catalyst layer of 1960kPaG, a gas temperature at the outlet of the catalyst layer of 880 ° C, and a GHSV of methane basis = 2,500 / hour. (Mole ratio) = 1: 1 raw material gas. The conversion rate of CH ₄ after 5 hours from the start of the reaction was 53.9% (equal conversion rate of CH ₄ under experimental conditions = 54.8%), and the conversion rate of CH ₄ after 50 hours was 53.1%. After 50 hours, the amount of carbon on the catalyst unloaded by four divisions in the same manner as in Example 1 was 0.6 wt%, 0.4 wt%, 0.1 wt%, and 0.05 wt%, respectively, in that order from the top. In addition, when analyzed with a catalyst treated under the pretreatment conditions described in Comparative Reaction Example 10, it was confirmed that Rh in particulate form exists on the surface of the catalyst.

    <Comparative Example 11>    

When the CaO content is 0.001wt% or less and the MgO powder with a purity of 99.9wt% or more is converted to Ca by boiling at 100 ° C to form Mg (OH) ₂ , the Ca (OH) ₂ aqueous solution is dropped at the same time. After stirring, Ca-added Mg (OH) ₂ particles were obtained. In this additive, 3.0 wt% of carbon as a lubricating material was mixed to form 1/4 inch diameter particles. The formed particles were calcined in air at 1060 ° C for 3 hours to obtain a catalyst carrier. The BET specific surface area of the obtained catalyst carrier was 0.50 m ² / g.

When the obtained catalyst carrier was analyzed by ICP in the same manner as in Example 1, the catalyst carrier contained CaO, and was 0.001% by weight in terms of Ca. Furthermore, from the results of EPMA analysis, it was confirmed that Ca was not present inside the catalyst carrier, and that Ca existed only near the surface of the MgO particles. In addition, the obtained MgO particles constituting the catalyst carrier were significantly larger than 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 near the surface of the MgO particles. In addition, the obtained catalyst carrier was in the same particle shape as in Example 1. Part of the surface of the MgO particles was covered with a layer containing CaO, and CaO was present in the concave portion on the surface of the MgO particles. In addition, these CaO exist on the surface of the self-catalyst carrier within a depth of 10%. In addition, when the amount of CaO present on the surface of the MgO particles is determined, the Ca conversion is 0.02 mg-Ca / m ² . In addition, the central portion of the peanut-shaped particles contains only a small amount of Ca, and almost all of the Ca is contained in both end portions.

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

The obtained catalyst contained Ru at a ratio of 910 wtppm to the catalyst, and the BET specific surface area was 0.10 m ² / g. When the obtained catalyst was subjected to EPMA analysis in the same manner as in Example 1, Ru was supported on the surface of the catalyst particles. Moreover, Ru exists in a region within 10% of the depth from the surface of the catalyst. Therefore, CaO exists near this Ru.

    <Comparative Reaction Example 11>    

50 cc of the catalyst prepared in Comparative Example 11 was filled in the same reactor as that of the user of Example 1, and a CO ₂ modification test of methane was performed.

Specifically, first, the catalyst was passed through the catalyst layer at 500 ° C. for 1 hour by using a mixed gas having a molar ratio of H ₂ and H ₂ O (H ₂ / H ₂ O = 1/0) in advance. After contacting with the catalyst for reduction treatment, CH ₄ : CO ₂ : H ₂ O is treated under the conditions of a gas pressure at the outlet of the catalyst layer of 1960kPaG, a gas temperature at the outlet of the catalyst layer of 880 ° C, and a GHSV of methane basis = 2,500 / hour. (Mole ratio) = 1: 1 raw material gas. The conversion rate of CH ₄ after 5 hours from the start of the reaction was 53.9% (equal conversion rate of CH ₄ under experimental conditions = 54.8%), and the conversion rate of CH ₄ after 50 hours was 53.3%. After 50 hours, the amount of carbon on the catalyst unloaded in four divisions in the same manner as in Example 1 was 0.5 wt%, 0.5 wt%, 0.1 wt%, and 0.05 wt%, respectively, from the top. In addition, when analyzed with a catalyst treated under the pretreatment conditions described in Comparative Reaction Example 11, it was confirmed that Ru in particulate form exists on the surface of the catalyst.

The manufacturing conditions of Examples 1 to 13 and Comparative Examples 1 to 11 and the properties of the obtained carrier and catalyst are shown in Table 3. 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 upgrading reaction using the catalysts of Examples 1 to 10 manufactured using the catalyst carrier of the present invention, the amount of carbon deposited was significantly lower (see Reaction Examples 1 to 10). . In addition, even when ventilated for a long time, the methane conversion rate can be maintained, and the synthesis gas can be produced stably and efficiently for a long period of time.

In addition, the calcination temperature was low, Comparative Example 1 in which CaO was not precipitated 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 containing carbon with an amount of CaO outside the range of the present invention There are many and carbon precipitation occurs in a short time (refer to Comparative Reaction Examples 1 to 11). Moreover, the conversion rates of CH _{4 of} Comparative Examples 1 and 3 to 8 were also lower than those of Examples.

In addition, Examples 11 to 13 show examples in which a catalyst was produced by using a catalyst carrier of the present invention to support catalyst metals other than Rh and Ru. These catalysts can be used in reactions other than the CO ₂ reforming reaction, and in this case, the precipitation of carbon can be suppressed.

Claims (9)

    A catalyst carrier, which is a magnesium oxide-based catalyst carrier, containing magnesium oxide particles and calcium oxide existing near the surface of the magnesium oxide particles. The content of the calcium oxide relative to the entire particle is 0.005 mass% in terms of Ca. ~ 1.5% by mass.     The catalyst carrier according to claim 1, wherein the calcium oxide content per unit surface area of the aforementioned magnesium oxide particles is 0.05 mg-Ca / m ² to 150 mg-Ca / m ² in terms of Ca conversion.     For example, the catalyst carrier of claim 1, wherein the vicinity of the aforementioned surface of the aforementioned magnesium oxide particles has an area within a depth of 10% of the maximum depth of each particle.         The catalyst carrier according to claim 1, wherein a calcium oxide-containing layer is formed near the aforementioned surface of the aforementioned magnesium oxide particles.         A method for manufacturing a catalyst carrier, which is a method for manufacturing a magnesium oxide-based catalyst carrier, which is characterized in that the raw material magnesium oxide particles are agglomerated by the step of calcining raw material magnesium oxide particles containing calcium oxide at a temperature of 1000 ° C or higher. The magnesium oxide particles are formed, while calcium oxide is precipitated near the surface of the magnesium oxide particles, and calcium oxide is contained near the surface of the magnesium oxide particles. The content of the calcium oxide relative to the entire particle is 0.005 mass% in terms of Ca. ~ 1.5% by mass of catalyst carrier.         For example, the method for manufacturing a catalyst carrier according to claim 5, which comprises adding carbon in a range of 1% by mass to 5% by mass with respect to the aforementioned raw material magnesium oxide particles, and then calcining.     The method for manufacturing a catalyst carrier according to claim 5, wherein the aforementioned catalyst carrier is a calcium oxide content per unit surface area of the aforementioned magnesium oxide particles, and is 0.05 mg-Ca / m ² to 150 mg-Ca / m ² in terms of Ca conversion.     The method for manufacturing a catalyst carrier according to claim 5, wherein the catalyst carrier is a region near the aforementioned surface of the aforementioned magnesium oxide particles, and the depth from the surface is within 10% of the maximum depth of each particle.         The method for manufacturing a catalyst carrier according to claim 5, wherein the catalyst carrier is formed near the surface of the magnesium oxide particles to form a calcium oxide-containing layer.