JP2010110671A - PEROVSKITE-BEARING Ni CATALYST MATERIAL FOR MODIFICATION AND METHOD OF MANUFACTURING SYNGAS USING THIS CATALYST MATERIAL - Google Patents

Abstract

The present invention provides a hydrocarbon reforming catalyst comprising a cation partially-substituted calcium titanate-supported nickel catalyst having a high degree of crystallinity and a method for producing synthesis gas using the same.
A cation partial substitution type in which strontium and iron are partially substituted by calcium and titanium lattice sites by supercritical or subcritical hydrothermal synthesis reaction, respectively, and the primary particle diameter is 50 nm or less. In addition to producing a calcium titanate carrier, a nickel catalyst having a primary particle size of 10 nm or less is produced, and this is supported on the carrier. The surface area is 70 square meters / g or more, there is no aggregation, and the crystallinity is Producing high calcium titanate supported nickel catalyst.
[Effect] A perovskite-supported Ni catalyst having a high surface area can be prepared and provided by a supercritical hydrothermal synthesis method.
[Selection] Figure 3

Description

The present invention relates to a cation partially substituted calcium titanate-supported nickel catalyst, a method for producing the same, and a method for producing a synthesis gas using the catalyst, and more particularly, as a catalyst for a partial oxidation reaction of methane. Cationic partially substituted calcium titanate (Ca _0.8 Sr _0.2 Ti _1-x having a rhomboid structure with a high surface area with a particle size of 50 nm or less, a surface area of 70 square meters / g or more, and no aggregation. The present invention relates to a method of simply supporting a nickel catalyst on (Fe _x O _3−δ ) fine particles and a method of producing a synthesis gas comprising a mixed gas of carbon monoxide and hydrogen using the nickel catalyst.

  The present invention is a novel nickel-supported cation partially substituted titanium that can produce and provide a cation partially substituted calcium titanate-supported nickel catalyst characterized by a high surface area by atomization in a simple process. The present invention provides a new technology and a new product relating to a method for producing a calcium acid catalyst and a method for producing a synthesis gas comprising a mixed gas of carbon monoxide and hydrogen using the catalyst.

  Due to the depletion of petroleum resources, expectations are rising for the technology for using natural gas as an energy resource. Among the natural gas utilization technologies, in particular, as the effective utilization technology of natural gas, the main reaction of the technology to convert natural gas into liquid fuels such as ethanol and gasoline, methane to synthesis gas (mixed gas of carbon monoxide and hydrogen) The development of catalysts that oxidatively convert to) is an urgent issue. In particular, a mixed conductive ceramic-supported nickel catalyst has attracted attention as a catalyst because it has not only catalytic activity but also high carbon deposition suppression ability.

In the mixed conductive ceramics used for the catalyst, a part of the constituent metal of the oxide having a perovskite structure (general formula; ABO ₃ ) is partially substituted with a metal having a lower valence. Then, oxygen vacancies are introduced into the oxide, and the function of carbon deposition resistance is exhibited by utilizing the electron and oxygen ion conductivity expressed thereby. A mixed conductive perovskite oxide, with high compositional homogeneity and crystallinity, as well as a high catalytic reaction rate and carbon deposition if the particle size (nanosize) and surface area can be increased by lowering the sintering temperature. It is considered that a highly active catalyst can be realized.

So far, based on calcium titanate (CaTiO _3), a portion of Ca was partially substituted by Sr, the cationic portion substituted calcium titanate _{(Ca 0.8 Sr 0.2 Ti 1-} x Fe x O 3 _-Δ ) is known to exhibit high activity as a catalyst support for a partial oxidation reaction catalyst of methane (Non-patent Document 1).

Further, based on calcium titanate (CaTiO ₃ ), a part of Ca is partially substituted with Sr, and a part of Ti is partially substituted with Fe, and cation partially substituted calcium titanate (Ca _0.8 Sr _{0.2 Ti 1-x Fe x O 3} -δ) represents oxygen and mixed conducting electrons, this property is in partial oxidation reaction of methane, greatly contributes to the expression of the function of inhibiting carbon deposition on the catalyst (Non-Patent Document 2).

  Preparation of the cation partially substituted calcium titanate (hereinafter sometimes referred to as partially substituted calcium titanate) by the sol-gel method has been studied. Thus, it is expected that high catalytic activity can be obtained if fine particles having mixed conductivity and high crystallinity can be used. For this purpose, cation partially-substituted calcium titanate fine particles having high crystallinity and having a particle diameter of 50 nm or less and a surface area of 60 square meters / g or more are required.

  The partially substituted calcium titanate-supported nickel catalyst using the partially substituted calcium titanate as a nickel catalyst carrier is mainly produced by a sol-gel method. In the sol-gel method, calcium carbonate, strontium carbonate, tetraisopropyl orthotitanate, iron citrate, and nickel citrate are used as raw materials.

  In the sol-gel method, each raw material is mixed with a mixed solution of citric acid and ethylene glycol, mixed in a predetermined amount, and heated in air, so that it is gradually converted into amorphous or partially by a hydrolysis reaction with a salt. A partially crystallized partially substituted calcium titanate and nickel precursor precursor was obtained and heat treated at 850 ° C. (Non-patent Document 2). However, although the particles obtained by this method have high crystallinity, the particle diameter is several tens of μm. Therefore, the obtained particles are pulverized by pulverization and classification, but at most about several hundred nm. The surface area is only about 1 square meter / g.

Angrew. Chem. Int. Ed. Engle. , 35, 192, (2006) Catal. Today, 117, 297, (2006)

  In such a situation, in view of the prior art, the present inventors have a high degree of crystallinity, single crystallinity, and a high surface area of 70 square meters / g or more. We conducted extensive research with the goal of developing a new technology that can produce calcium titanate-supported nickel catalysts efficiently, in a simple process, and in a short time. As a result, the present inventors achieved the intended purpose by hydrothermal reaction of calcium ions, strontium ions, titanium ions, iron ions and nickel ions in subcritical or supercritical water. As a result, the present invention has been completed.

  The present invention has been made by paying attention to the above-mentioned problems, and efficiently produces a partially substituted calcium titanate-carrying nickel catalyst having a high surface area of 70 square meters / g or more in a short time. It is an object of the present invention to provide a method for producing a partially-substituted calcium titanate-supported nickel catalyst that can be used, and a catalyst product thereof.

  The present invention also provides a hydrocarbon for obtaining a synthesis gas that is a mixture of hydrogen and carbon monoxide from a hydrocarbon such as natural gas and a reforming gasifying agent such as water, carbon dioxide, oxygen, and air. An object of the present invention is to provide a synthesis gas production method using the catalyst as a reforming catalyst.

The present invention for solving the above-described problems comprises the following technical means.
(1) Basic structure of the general formula _{Ni / Ca 0.8 Sr 0.2 Ti 1} -x Fe x O 3-δ
(Wherein x is a number from 0.1 to 0.3, δ is a number from 0.05 to 0.15),
The Ca _0.8 Sr _0.2 Ti _1-x Fe _x O _3-δ is a small fine particle carrier having a primary particle diameter of more than 0 to 50 nm, and the primary particle diameter is more than 0 to A high crystal supporting Ni catalyst having an atomic ratio of Ni / (Ca + Sr) of 0.2 to 1.0 at 10 nm, having a high surface area of at least 70 square meters / g, no aggregation, and high crystallinity. Cationic partially substituted calcium titanate-supported nickel catalyst.
(2) The cation partially substituted calcium titanate-carrying nickel catalyst according to (1), wherein the cation partially substituted calcium titanate carrying a Ni catalyst has a single crystal structure.
(3) The cation partially substituted calcium titanate-carrying nickel catalyst according to (1), wherein the primary particle diameter of the Ni catalyst is more than 0 to 10 nm.
(4) By mixing a titanium compound aqueous solution, a calcium salt aqueous solution, a strontium salt aqueous solution, and an iron salt aqueous solution, adding an alkaline aqueous solution, and then hydrothermally reacting in subcritical or supercritical water, the basic structure of the general formula _{Ca 0.8 Sr 0.2 Ti 1-x} Fe x O 3-δ
(Wherein x is a number from 0.1 to 0.3, and δ is a number from 0.05 to 0.15). By adding and hydrothermally reacting in subcritical or supercritical water, the basic structure has the general formula Ni / Ca _0.8 Sr _0.2 Ti _1-x Fe _x O _3-δ
A method for producing a cation partially-substituted calcium titanate-supported nickel catalyst represented by the formula:
(5) A titanium compound aqueous solution, a calcium salt aqueous solution, a strontium salt aqueous solution, an iron salt aqueous solution, and a nickel salt aqueous solution are mixed, an alkaline aqueous solution is added, and then a hydrothermal reaction is performed in subcritical or supercritical water. the process of the basic structure, the general formula _{Ni / Ca 0.8 Sr 0.2 Ti 1} -x Fe x O 3-δ
(Wherein x is a number from 0.1 to 0.3, and δ is a number from 0.05 to 0.15). A method for producing a cation partially substituted calcium titanate-supported nickel catalyst.
(6) The cation partially substituted calcium titanate-supported nickel according to (4) or (5), wherein the hydrothermal reaction hydrothermal treatment temperature is at most 400 ° C. and the reaction pressure is at most 35 MPa. A method for producing a catalyst.
(7) The method for producing a cation partially-substituted calcium titanate-supported nickel catalyst according to (4) or (5), wherein the hydrothermal treatment time of the hydrothermal reaction is more than 0 to 20 seconds.
(8) A mixed gas of carbon monoxide and hydrogen from a hydrocarbon and a reforming gasifying agent using the cation partially substituted calcium titanate-supported nickel catalyst according to any one of (1) to (3) A process for producing synthesis gas comprising obtaining a synthesis gas comprising:

Next, the present invention will be described in more detail.
The present invention, the basic structure is the general formula _{Ni / Ca 0.8 Sr 0.2 Ti 1} -x Fe x O 3-δ (x in the formula 0.1 to 0.3, [delta] is 0.05 a cationic moiety substituted calcium titanate supported nickel catalyst represented by 0.15 is the number of) the above-mentioned _{Ca 0.8 Sr 0.2 Ti 1-x} Fe x O 3-δ, primary particle size Is a carrier of small fine particles of more than 0 to 50 nm, and the carrier carries a Ni catalyst having a primary particle diameter of more than 0 to 10 nm and an atomic ratio Ni / (Ca + Sr) of 0.2 to 1.0. In addition, it is a highly crystalline cationic partially substituted calcium titanate-supported nickel catalyst having a high surface area of at least 70 square meters / g, no aggregation, and high crystallinity. Here, the primary particle diameter of more than 0 to 50 nm, or more than 0 to 10 nm means that the primary particle diameter is more than 0 and 50 nm or less, or more than 0 and 10 nm or less.

The present invention is also a method for producing the above cation partially substituted calcium titanate-supported nickel catalyst, comprising mixing an aqueous titanium compound solution, an aqueous calcium salt solution, an aqueous strontium salt solution, and an aqueous iron salt solution, and an alkaline aqueous solution. After the addition of, the basic structure is represented by the general formula Ca _0.8 Sr _0.2 Ti _1-x Fe _x O _3-δ (in the formula, by a hydrothermal reaction in subcritical or supercritical water. c is a number from 0.1 to 0.3, and δ is a number from 0.05 to 0.15). Thereafter, a nickel salt aqueous solution is added, by hydrothermal reaction in water in supercritical or supercritical state, the basic structure, the cation moiety substituted represented by the general formula _{Ni / Ca 0.8 Sr 0.2 Ti 1} -x Fe x O 3-δ titanium It is characterized in that to produce a calcium supported nickel catalyst.

The present invention also relates to a method for producing the above cation partially substituted calcium titanate-supported nickel catalyst, comprising mixing an aqueous titanium compound solution, an aqueous calcium salt solution, an aqueous strontium salt solution, an aqueous iron salt solution, and an aqueous nickel salt solution. Then, after adding the alkaline aqueous solution, the basic structure is represented by the general formula Ni / Ca _0.8 Sr _0.2 Ti _1-x Fe _x O ₃ by a hydrothermal reaction in subcritical or supercritical water. _-Δ (wherein x is a number between 0.1 and 0.3, and δ is a number between 0.05 and 0.15). It is what.

  Furthermore, the present invention is a method for producing a synthesis gas comprising a mixed gas of carbon monoxide and hydrogen using the cation partially substituted calcium titanate supported nickel catalyst, wherein the hydrocarbon and the hydrocarbon are partially oxidized. Production of synthesis gas consisting of a mixture of carbon monoxide and hydrogen from ordinary reforming gasifiers used as oxidants such as water vapor, carbon dioxide, oxygen, air, etc. It is characterized by doing.

  There are two production methods for producing the partially substituted calcium titanate-supported nickel catalyst of the present invention. The first method for producing the partially substituted calcium titanate-supported nickel catalyst of the present invention is as follows. First, calcium ions, strontium ions, titanium ions and iron ions are hydrothermally reacted in subcritical or supercritical water. Producing an orthorhombic partially substituted calcium titanate oxide having a primary particle size of 50 nm or less, the particles having little residual hydroxide ions, no aggregation, and high crystallinity; Partially-substituted calcium titanate-supported nickel by adding nickel ions to the reaction line and causing a hydrothermal reaction in subcritical or supercritical water to produce a nickel catalyst having a primary particle size of 10 nm or less A catalyst material is produced.

  The second method for producing the partially substituted calcium titanate-supported nickel catalyst of the present invention is to hydrocalcite calcium ions, strontium ions, titanium ions, iron ions and nickel ions in subcritical or supercritical water. By reacting, the partially substituted calcium titanate-supported nickel catalyst having a primary particle diameter of 50 nm or less, the particles having little residual hydroxide ions, no aggregation, and the catalyst was mixed in the carrier fine particles. The material is manufactured. In order to produce a partially substituted calcium titanate-carrying nickel catalyst material having these characteristics, it is necessary to suppress aggregation of nuclei generated by the reaction and to suppress generation of secondary nuclei on the crystal surface.

  In general, in order to increase the crystallinity of a metal oxide, it is desirable to perform a high temperature treatment. However, in a high-temperature, high-pressure subcritical or supercritical state, water becomes a nonpolar gaseous state and has a nonpolar part. The generation rate of the substituted calcium titanate oxide and the nickel catalyst is remarkably increased, and the dissolved ion concentration is extremely low. Therefore, secondary nucleation and excessive crystal growth are unlikely to occur, and the generated particle size is also small. , Get smaller.

In the present invention, titanium alkoxide is used as the titanium source. The titanium source is preferably water-soluble. For example, a slurry containing a solid product titanium hydroxide (TiO ₂ xH ₂ O) obtained by hydrolyzing an appropriate Ti compound is desirable. The calcium source, strontium source, iron source and nickel source are preferably water-soluble, and for example, calcium nitrate, strontium nitrate, iron nitrate and nickel nitrate are preferably used. It is necessary to add an alkali to the above solution or mixed solution of calcium ion, strontium ion, titanium ion and iron ion to obtain a solution having a pH higher than neutrality. Here, NaOH or KOH is suitable as the alkali, but KOH is preferably used.

  In the method for producing a partially substituted calcium titanate-carrying nickel catalyst according to the present invention, it is preferable that the hydrothermal synthesis reaction by rapid temperature increase is performed under conditions where hydroxide ions are appropriately added. In this way, it is easy to crystallize in the temperature rising process by adding a hydroxide ion to the mixed aqueous solution of calcium ion, strontium ion, titanium ion and iron ion, and nickel aqueous solution to make it alkaline. Titanium hydroxide is easily dissolved.

  In this way, the by-products generated in these temperature rising processes remain in the reaction product, adversely affect the crystal quality, and the yield of the desired partially substituted calcium titanate-supported nickel catalyst. Can be prevented. Therefore, in the method for producing the partially substituted calcium titanate-supported nickel catalyst of the present invention, the hydrothermal reaction is carried out using a mixed solution of calcium ions, strontium ions, titanium ions and iron ions, and a nickel ion solution as subcritical to supercritical. It is preferable to carry out by rapidly raising the temperature to a predetermined temperature at which a critical state is obtained.

  In the first production method of the partially substituted calcium titanate-supported nickel catalyst of the present invention, after the partially substituted calcium titanate fine particles are generated, the nickel catalyst particles are sublimated or supercritically for a predetermined time, It is preferable to improve the crystallinity of the nickel catalyst particles and the partially substituted calcium titanate fine particles without growing them by hydrothermal treatment. In the present invention, high crystallinity is defined as meaning that a partially substituted calcium titanate serving as a carrier forms a perovskite structure that does not contain crystal water or a hydroxyl group with a target composition.

  In the second method for producing the partially substituted calcium titanate-supported nickel catalyst of the present invention, the partially substituted calcium titanate fine particles and the nickel catalyst particles are hydrothermally treated for a predetermined time under subcritical or supercritical conditions. These are preferably produced at the same time, and the nickel catalyst particles and the partially substituted calcium titanate fine particles are not grown but dispersed. In the present invention, the hydrothermal reaction temperature of the hydrothermal reaction in subcritical or supercritical water is a subcritical or supercritical water condition, and the temperature and pressure conditions are 400 ° C. or less. The reaction pressure is 35 MPa or less. Moreover, the hydrothermal treatment time of the hydrothermal reaction is a short time of more than 0 and 20 seconds or less.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an example of a flow-through hydrothermal synthesizer used for producing the partially substituted calcium titanate-supported nickel catalyst of the present invention. This equipment consists of a raw material mixture of calcium nitrate aqueous solution, strontium nitrate aqueous solution, iron nitrate aqueous solution and titania sol solution, nickel aqueous solution, alkaline aqueous solution and distilled water, or calcium nitrate aqueous solution and strontium nitrate aqueous solution. , Iron nitrate aqueous solution, nickel nitrate aqueous solution, titania sol raw material mixed aqueous solution, alkaline aqueous solution and high pressure pump for liquid chromatography for feeding distilled water (4 units), reaction tube, and electric furnace for heating distilled water ( 2 units), a heat exchanger for cooling the reaction liquid, and a pressure regulator (back pressure valve).

  In the production method (1), a titania sol solution in a glass container, a calcium nitrate aqueous solution, a strontium nitrate aqueous solution, a raw material mixed solution 1 of an iron nitrate aqueous solution, and an alkaline aqueous solution 3 such as potassium hydroxide are used for high performance liquid chromatography. With the pulsating pumps 2 and 4, for example, the liquid is fed at a flow rate of 10 ml / min. The nickel nitrate aqueous solution 9 is fed by another high-pressure pump 10 at a flow rate of 10 ml / min, for example. On the other hand, the distilled water 5 is sent to the tubular electric furnace 7 by another high-pressure pump 6 at a flow rate of 55 ml / min, for example, and the distilled water is supercritical water necessary for heating the raw material solution. . The metal ion-containing mixed aqueous solution and the potassium hydroxide aqueous solution are mixed at the mixing point 1, contacted with the supercritical water at the mixing point 2, rapidly heated to the reaction temperature, and the hydrothermal reaction is started. .

  The reaction liquid stays in the reaction tube 8 maintained at a constant temperature by a tubular electric furnace for a certain period of time, and then comes into contact with the nickel aqueous solution at the mixing point 3 and is rapidly heated to the reaction temperature. The reaction is started. After staying in the reaction tube 8 for a certain period of time, the reaction tube 8 is cooled by the double-tube heat exchanger 11 at the reaction tube outlet, and then the pressure is reduced by the back pressure valve 12 and collected in the collection container 13.

  In the production method (2), a titania sol solution, a calcium nitrate aqueous solution, a strontium nitrate aqueous solution, an iron nitrate aqueous solution, a nickel nitrate aqueous solution mixed solution 1 and a potassium hydroxide aqueous solution 3 in a glass container are used for high performance liquid chromatography. With the pulsating pumps 2 and 4, for example, the liquid is fed at a flow rate of 10 ml / min. On the other hand, the distilled water 5 is sent to the tubular electric furnace 7 by another high-pressure pump 6 at a flow rate of 55 ml / min, for example, and the distilled water is supercritical water necessary for heating the raw material solution. .

  The metal ion-containing mixed aqueous solution and the potassium hydroxide aqueous solution are mixed at the mixing point 1, contacted with the supercritical water at the mixing point 2, rapidly heated to the reaction temperature, and the hydrothermal reaction is started. The reaction liquid stays in the reaction tube 8 maintained at a constant temperature for a certain period of time by a tubular electric furnace, is cooled by the double-tube heat exchanger 11 at the outlet of the reaction tube, and is then depressurized by the back pressure valve 12. And collected in a collection container 13.

  The produced particles are recovered as a slurry together with the reaction liquid from the outlet. The collected solution is filtered through an appropriate filter, and the produced powder is collected. The characteristics of these particles identify the crystal structure by analyzing powder X-ray diffraction and electron diffraction images. The composition is determined by ICP emission spectrometry. The particle diameter and the degree of aggregation are evaluated by observation with an electron microscope.

  A method for producing synthesis gas using the catalyst of the present invention will be described. First, the partially substituted calcium titanate-supported catalyst of the present invention is used as a reforming catalyst, and the activation treatment of the reforming catalyst is performed at 873 to 1373 K, preferably 923 to a reducing gas stream such as hydrogen. It is carried out by holding the catalyst in the temperature range of 1323 K, more preferably 973 to 1273 K for 0.1 to 10 hours. The reducing air stream may be a gas stream containing a hydrocarbon used for the reaction and a reforming gasifying agent. By the activation treatment, the surface of the catalyst is reduced, and the oxide of the second component represented by Ni of the active metal species dispersed in the composite oxide is reduced as a metal element to obtain catalytic activity.

  Natural gas containing methane, ethane, LPG, naphtha, other crude oil fractions, and pre-reformed gas made from crude oil, coke oven gas, coal gas, etc. are used as hydrocarbons that are the raw material for synthesis gas It is done. Further, ethane, LPG, naphtha, and other crude oil fractions that hardly contain methane may be used as a raw material. Steam, carbon dioxide, oxygen, air or the like is used as the reforming gasifying agent, and a mixture of a plurality of these may be used. In the present invention, the reformed gasifying agent means an oxidizing agent that becomes an oxygen source when a hydrocarbon that is a raw material of synthesis gas is partially oxidized.

  Specific reaction conditions are a temperature of 873 to 1373 K, preferably 923 to 1323 K, more preferably 973 to 1273 K, and the ratio of the total flow rate F (ml / hr) of the introduced gas to the catalyst weight W (g). F / W is set within a range of 0 to 500,000 (ml / g · hr). The catalyst arrangement can be arbitrarily selected from known forms such as a fixed bed and a fluidized bed. The synthesis gas thus obtained is used as a suitable gas for efficiently synthesizing various industrial raw materials.

The present invention has the following effects.
1) A partially substituted type calcium titanate-carrying nickel catalyst having a high degree of crystallinity and containing no crystallization water or hydroxyl group can be produced.
2) A partially-substituted calcium titanate-carrying nickel catalyst comprising monocrystalline orthorhombic partially-substituted calcium titanate fine particles having a particle diameter of 50 nm or less and a nickel catalyst having a particle diameter of 10 nm or less can be produced and provided.
3) A high surface area catalyst having a surface area of 70 square meters / g or more can be provided.
4) The partially substituted calcium titanate-supported nickel catalyst fine particles of the present invention can be applied to a practical high-performance catalyst having excellent reforming ability used when reforming hydrocarbons such as natural gas.
5) An efficient synthesis gas production technique using the partially substituted calcium titanate-supported nickel catalyst can be provided.

  EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited at all by these examples.

(1) Flow-through hydrothermal synthesis reaction apparatus In this example, the flow-through hydrothermal synthesis reaction apparatus shown in FIG. 1 was used.
First, as a production method (1), in the flow-type hydrothermal synthesis reactor of FIG. 1, each metal ion-containing mixed aqueous solution of titania sol solution, calcium nitrate aqueous solution, strontium nitrate aqueous solution, and iron nitrate aqueous solution in a glass container is used. The raw material mixed solution (Metal salt solution) 1 and the potassium hydroxide aqueous solution (Alkali solution) 3 were fed at a flow rate of 10 ml / min by the non-pulsating high-pressure pumps 2 and 4 for high performance liquid chromatography. The aqueous nickel nitrate solution 9 was fed at a flow rate of 10 ml / min by another high pressure pump 10 for liquid chromatography.

  On the other hand, the distilled water in the distilled water tank 5 is sent to a tubular electric furnace (Heater) 7 at a flow rate of 55 ml / min by another high pressure pump 6 for liquid chromatography, where the distilled water is The supercritical water necessary for heating the raw material solution was used. The metal ion-containing mixed aqueous solution and the potassium hydroxide aqueous solution are mixed at a mixing point 1, contacted with the supercritical water at the mixing point 2, and rapidly heated to the reaction temperature. To initiate a hydrothermal reaction.

  The reaction solution stays in a reactor 8 maintained at a constant temperature by a tubular electric furnace for a certain period of time, and then is brought into contact with a nickel nitrate aqueous solution at a mixing point 3 to rapidly react with the reaction temperature. The temperature was raised to 0 to initiate a hydrothermal reaction with the aqueous nickel nitrate solution. These reaction liquids stay in the reaction tube 8 for a certain period of time, are cooled by a double-tube heat exchanger (Cooler) 11 at the outlet of the reaction tube, and are then depressurized by a back pressure valve (Back-pressure regulator) 12. It collected in the collection | recovery container (Collector) 13.

  Next, as a production method (2), in the flow-type hydrothermal synthesis reactor of FIG. 1, raw materials for titania sol solution, calcium nitrate aqueous solution, strontium nitrate aqueous solution, iron nitrate aqueous solution, nickel nitrate aqueous solution in a glass container The mixed solution 1 and the potassium hydroxide aqueous solution 3 were fed at a flow rate of 10 ml / min by the non-pulsating high pressure pumps 2 and 4 for high performance liquid chromatography.

  On the other hand, the distilled water in the distilled water tank 5 is sent to the tubular electric furnace 7 at a flow rate of 55 ml / min by another high pressure pump 6 for liquid chromatography, where the distilled water is necessary for heating the raw material solution. Supercritical water was used. The metal ion-containing mixed aqueous solution and the potassium hydroxide aqueous solution are mixed at the mixing point 1, contacted with the supercritical water at the mixing point 2, rapidly raised to the reaction temperature, and the hydrothermal reaction is started. It was.

  The reaction liquid stays in the reaction tube 8 held at a constant temperature by a tubular electric furnace for a certain period of time, is cooled by a double-tube heat exchanger 11 at the outlet of the reaction tube, and is lowered by a back pressure valve 12. And collected in a collection container 13.

(2) Catalyst synthesis Using flow-through hydrothermal synthesis reactors, the concentrations of the titania sol, calcium nitrate, strontium nitrate, iron nitrate, and potassium hydroxide raw material solutions were 0.045M and 0.04M, respectively. , 0.01M, 0.005M, and 1.00M, these mixed salt solution and potassium hydroxide solution are fed at a flow rate of 10 ml / min, reaction temperature is 400 ° C., reaction pressure is 30 MPa, and residence time is 11 seconds. On the other hand, nickel nitrate is fed at 0.025M as the concentration of the raw material solution, and a hydrothermal synthesis reaction is performed under the conditions of a reaction temperature of 362 ° C., a reaction pressure of 30 MPa, and a residence time of 0.2 seconds. As a product, the structure has the general formula 0.5Ni / Ca _0.8 Sr _0.2 Ti _0.9 Fe _0.1 O _3-δ
A cation partially substituted calcium titanate-supported nickel catalyst of the product of the present invention represented by (δ in the formula is a number from 0.05 to 0.15) was obtained.

  FIG. 2 shows an electron microscope image of the obtained product. From the figure, it can be seen that the particle diameter of the substituted calcium titanate is 50 nm or less, and each particle is separated and not aggregated. The electron diffraction pattern also confirms that the crystal structure of these particles is attributed to orthorhombic calcium titanate, and that the strontium and iron dopants are replaced by calcium and titanium sites. It was. Moreover, the particle diameter of the nickel catalyst was 10 nm or less, and was mixed with substituted calcium titanate particles. The surface area of the partially substituted calcium titanate-supported nickel catalyst material produced according to the present invention was 91.4 square meters / g.

  In Example 1, the hydrothermal synthesis reaction was performed under the same conditions as in Example 1 except that the concentration of the nickel nitrate raw material solution was changed to 0.05 and 0.01M. FIG. 3 shows an XRD chart (profile) of the product when the concentration of the nickel nitrate raw material solution is changed. In both cases, it was confirmed that a substituted calcium titanate-supported nickel catalyst material was formed. Here, the surface area of the partially substituted calcium titanate-carrying nickel catalyst material produced by performing the hydrothermal synthesis reaction under the condition that the concentration of the nickel nitrate raw material solution is 0.05 and 0.01 M, respectively, is 117. 8 and 75.5 square meters / g.

The concentration of each raw material solution of titania sol, calcium nitrate, strontium nitrate, iron nitrate, nickel nitrate, and potassium hydroxide was 0.045M, 0.04M,. These mixed salt solution and potassium hydroxide solution were fed at a flow rate of 10 ml / min at 01M, 0.005M, 0.025M, and 1.00M, reaction temperature 400 ° C., reaction pressure 30 MPa, residence time 11 seconds. The hydrothermal synthesis reaction is performed under the conditions: and the product has a basic structure of the general formula 0.5Ni / Ca _0.8 Sr _0.2 Ti _0.9 Fe _0.1 O _3-δ
A cation partially substituted calcium titanate-supported nickel catalyst of the product of the present invention represented by (δ in the formula is a number from 0.05 to 0.15) was obtained.

  FIG. 4 shows an electron microscope image of the obtained product. From the figure, it can be seen that the particle diameter of the substituted calcium titanate is 50 nm or less, and each particle is separated and not aggregated. The electron diffraction pattern also confirms that the crystal structure of these particles is attributed to orthorhombic calcium titanate, and that the strontium and iron dopants are replaced by calcium and titanium sites. It was. Moreover, the particle diameter of the nickel catalyst was 10 nm or less, and was mixed with substituted calcium titanate particles. The surface area of the partially substituted calcium titanate-carrying nickel catalyst material produced according to the present invention was 99.02 square meters / g.

  In Example 3, the hydrothermal synthesis reaction was performed under the same conditions as in Example 3 except that the concentration of the nickel nitrate raw material solution was changed to 0.05 and 0.01M. FIG. 5 shows an XRD chart (profile) of the product when the concentration of the nickel nitrate raw material solution is changed. In both cases, it was confirmed that a substituted calcium titanate-supported nickel catalyst material was formed.

19 to 150 mg of the partially substituted type calcium titanate-carrying nickel catalyst shown in Example 1 was filled and fixed in a quartz reaction tube, and the reaction was evaluated by a flow-type hydrothermal synthesis reactor. Prior to the reaction evaluation, the catalyst was kept at 1173 K for 7.5 to 60 minutes in a hydrocarbon (CH ₄ ) gas stream used for the reaction to activate the catalyst. In the reaction evaluation, at 873 to 1173K, the F / W, which is the ratio between the total flow rate F (ml / hr) of the introduced gas and the catalyst weight W (g), is 35000 to 280000 (ml / g · hr). From the analysis of the reaction tube outlet gas when hydrogen was supplied, the activity of the catalyst was evaluated. The product was mostly carbon monoxide and hydrogen, the other being a small amount of water and carbon dioxide.

FIG. 6 shows the CH ₄ conversion rate at 873 to 1173K with respect to F / W. The CH ₄ conversion, CO selectivity and H ₂ / CO ratio during the reaction were 7 to 100%, 94 to 99% and 1.8 to 2.0, respectively. Here, the CH ₄ conversion rate is obtained by dividing the difference between the supply amount and discharge amount of CH _{4 by} the supply amount. Further, after conducting the catalytic reaction experiment at 1173 K for 6 hr, a very small amount of carbon was observed in the recovered catalyst sample, which was 0.9 wt% of the catalyst weight before the reaction.

19 to 150 mg of the partially substituted type calcium titanate-carrying nickel catalyst shown in Example 3 was filled and fixed in a quartz reaction tube, and the reaction was evaluated by a flow-type hydrothermal synthesis reactor. Prior to the reaction evaluation, the catalyst was kept at 1173 K for 7.5 to 60 minutes in a hydrocarbon (CH ₄ ) gas stream used for the reaction to activate the catalyst. The reaction evaluation was conducted at 873 to 1173K at a ratio F / W of 35,000 to 280000 (ml / g · hr), which is a ratio of the total flow rate F (ml / hr) of the introduced gas and the catalyst weight W (g). From the analysis of the reaction tube outlet gas when hydrogen was supplied, the activity of the catalyst was evaluated. The product was mostly carbon monoxide and hydrogen, the other being a small amount of water and carbon dioxide.

FIG. 7 shows the CH ₄ conversion rate at 873 to 1173K with respect to F / W. CH ₄ conversion, CO selectivity and H ₂ / CO ratio during the reaction were 5 to 100%, 89 to 99% and 1.9 to 2.0, respectively. Here, the CH ₄ conversion rate is obtained by dividing the difference between the supply amount and the discharge amount of CH _{4 by} the supply amount. Further, after conducting the catalytic reaction experiment at 1173 K for 6 hr, a very small amount of carbon was observed in the recovered catalyst sample, which was 0.4 wt% of the catalyst weight before the reaction.

Comparative Example 1
A stock solution of catalyst components was prepared by the following procedure by the sol-gel method. A solution obtained by dissolving 63 g of citric acid and 56 ml of ethylene glycol in about 350 ml of water, gradually dissolving 10 g of calcium carbonate in this aqueous solution, and making the total amount 1,000 ml with water was used as a calcium stock solution. A solution obtained by dissolving 63 g of citric acid and 56 ml of ethylene glycol in about 350 ml of water, gradually dissolving 14.76 g of strontium carbonate in this aqueous solution, and then making the total amount 1,000 ml with water, did.

  105 g of citric acid and 112 ml of ethylene glycol were dissolved in about 350 ml of water, and 28.4 g of tetraisopropyl orthotitanate was added to this aqueous solution. When the solution was vigorously stirred, the resulting white precipitate gradually dissolved and became a clear solution. To this was added water to make a total volume of 500 ml, which was used as a titanium stock solution. 42 g of citric acid and 84 ml of ethylene glycol were dissolved in about 200 ml of water, and 42.0 g of iron citrate was dissolved in this aqueous solution, and then the total amount was made 500 ml with water to obtain an iron stock solution.

  Dissolve 252 g of citric acid and 336 ml of ethylene glycol in about 600 ml of water, dissolve 50.0 g of basic nickel carbonate tetrahydrate in this aqueous solution, and then add a total solution of 1,000 ml with water to a nickel stock solution. did. A catalyst was prepared from the stock solution thus obtained by the following procedure. 400 ml of calcium stock solution, 100 ml of strontium stock solution, 225 ml of titanium stock solution, 25 ml of iron stock solution, and 125 ml of nickel stock solution were mixed, concentrated with a rotary evaporator, and then dried on a hot plate. This was put into an electric furnace, heated to 500 ° C. in air, and baked for 5 hours.

The solid obtained here was powdered in a mortar and mixed well. Again, calcination was performed in air at 850 ° C. for 5 hours, and the basic structure was the general formula Ni / Ca _0.8 Sr _0.2 Ti _0.9 Fe _0.1 O _3-δ
A partially substituted calcium titanate-supported nickel catalyst represented by the formula (where δ is a number from 0.05 to 0.15) was obtained. The particle size of the substituted calcium titanate prepared by the sol-gel method was as large as 100 nm or more and was indefinite. Further, the surface area was as low as 6.13 square meters / g.

Comparative Example 2
Using the partially substituted calcium titanate-carrying nickel catalyst shown in Comparative Example 1, a catalytic reaction experiment was performed in the same manner as shown in Example 5 and Example 6. FIG. 8 shows the CH ₄ conversion rate at 873 to 1173 K with respect to F / W, which is the ratio of the total flow rate F (ml / hr) of the introduced gas and the catalyst weight W (g). The CH ₄ conversion, CO selectivity, and H ₂ / CO ratio during the reaction were 5 to 99%, 79 to 99%, and 1.7 to 2.0, respectively.

  If the reaction temperature is higher or the F / W is smaller than those shown in Example 5 and Example 6 using the product of the present invention, sufficient reforming ability could not be shown. . Further, after carrying out the catalytic reaction experiment at 1173 K for 6 hr, a very small amount of carbon deposition, which was 0.5 wt% of the catalyst weight before the reaction, was observed in the recovered catalyst sample.

  Although the embodiments of the present invention have been specifically described with reference to the drawings, the present invention is not limited to these examples, and modifications and changes in these examples can be made without departing from the spirit of the present invention. Needless to say, the addition is included in the scope of the present invention.

  As described above in detail, the present invention relates to a partially substituted calcium titanate-supported nickel catalyst material and a method for producing the same. According to the present invention, for example, preparation of a catalyst using partially substituted calcium titanate as a carrier is provided. In this case, heat treatment for improving the degree of crystallinity is unnecessary, and it is possible to increase the surface area that greatly affects the reactivity of the catalyst. According to the present invention, a partially substituted type calcium titanate-carrying nickel catalyst material having a high crystallinity and a surface area of about 75 to 120 square meters / g is easily produced at a relatively low temperature and in a short time. be able to. By using the partially substituted calcium titanate fine particles of the present invention, nickel is supported as a reforming catalyst for natural gas and the like, so that the surface area of the catalyst is 70 square meters / g or more and the particle size is several tens of nanometers. To the extent that it can be prepared.

  The present invention makes it possible to provide a method for producing synthesis gas using a partially substituted calcium titanate-supported nickel catalyst according to the present invention as a reforming catalyst. According to the present invention, for example, As compared with the conventional sol-gel method, excellent reforming ability can be exhibited even when the reaction temperature is lower or the F / W, which is the ratio of the total flow rate F of the introduced gas and the catalyst weight W, is larger. INDUSTRIAL APPLICABILITY The present invention is useful for providing a reforming catalyst that can produce a synthesis gas suitable for efficiently synthesizing various industrial raw materials.

A flow-type hydrothermal synthesis reactor is shown. Shows an electron microscope image of _{0.5Ni / Ca 0.8 Sr 0.2 Ti 0.9} Fe 0.1 O 3-δ products shown in Example 1. Shows the XRD chart of _{Ni / Ca 0.8 Sr 0.2 Ti 0.9} Fe 0.1 O 3-δ products shown in Example 1. Shows an electron microscope image of _{0.5Ni / Ca 0.8 Sr 0.2 Ti 0.9} Fe 0.1 O 3-δ products shown in Example 3. Shows the XRD chart of _{Ni / Ca 0.8 Sr 0.2 Ti 0.9} Fe 0.1 O 3-δ products shown in Example 3. The CH ₄ conversion rate in the partial oxidation reaction of methane using Ni / Ca _0.8 Sr _0.2 Ti _0.9 Fe _0.1 O _3-δ of the present invention shown in Example 1 as a reforming catalyst is shown. . The CH ₄ conversion rate in the partial oxidation reaction of methane using Ni / Ca _0.8 Sr _0.2 Ti _0.9 Fe _0.1 O _3-δ of the present invention shown in Example 3 as a reforming catalyst is shown. . The CH ₄ conversion rate in the partial oxidation reaction of methane using Ni / Ca _0.8 Sr _0.2 Ti _0.9 Fe _0.1 O _3-δ as a reforming catalyst by the sol-gel method shown in Comparative Example 2 is shown. .

Explanation of symbols

1 Raw material mixed solution 1
2 High pressure pump for liquid chromatography 3 Potassium hydroxide aqueous solution 4 High pressure pump for liquid chromatography 5 Distilled water tank 6 High pressure pump for liquid chromatography 7 Electric furnace 8 Reaction tube 9 Nickel aqueous solution 10 High pressure pump for liquid chromatography 11 Double cooling tube 12 Back pressure valve 13 Container

Claims (8)

The basic structure of the general formula _{Ni / Ca 0.8 Sr 0.2 Ti 1} -x Fe x O 3-δ
(Wherein x is a number from 0.1 to 0.3, δ is a number from 0.05 to 0.15),
The Ca _0.8 Sr _0.2 Ti _1-x Fe _x O _3-δ is a small fine particle carrier having a primary particle diameter of more than 0 to 50 nm, and the primary particle diameter is more than 0 to A high crystal supporting Ni catalyst having an atomic ratio of Ni / (Ca + Sr) of 0.2 to 1.0 at 10 nm, having a high surface area of at least 70 square meters / g, no aggregation, and high crystallinity. Cationic partially substituted calcium titanate-supported nickel catalyst.   The cation partially substituted calcium titanate-carrying nickel catalyst according to claim 1, wherein the cation partially substituted calcium titanate carrying a Ni catalyst has a single crystal structure.   The cation partially-substituted calcium titanate-supported nickel catalyst according to claim 1, wherein the primary particle diameter of the Ni catalyst is more than 0 to 10 nm. The basic structure is obtained by mixing a titanium compound aqueous solution, a calcium salt aqueous solution, a strontium salt aqueous solution, and an iron salt aqueous solution, adding an alkaline aqueous solution, and then hydrothermally reacting in subcritical or supercritical water. , general formula _{Ca 0.8 Sr 0.2 Ti 1-x} Fe x O 3-δ
(Wherein x is a number from 0.1 to 0.3, and δ is a number from 0.05 to 0.15). By adding and hydrothermally reacting in subcritical or supercritical water, the basic structure has the general formula Ni / Ca _0.8 Sr _0.2 Ti _1-x Fe _x O _3-δ
A method for producing a cation partially-substituted calcium titanate-supported nickel catalyst represented by the formula: By mixing a titanium compound aqueous solution, calcium salt aqueous solution, strontium salt aqueous solution, iron salt aqueous solution, and nickel salt aqueous solution, adding an alkaline aqueous solution, and then hydrothermally reacting in subcritical or supercritical water. the basic structure has the general formula _{Ni / Ca 0.8 Sr 0.2 Ti 1} -x Fe x O 3-δ
(Wherein x is a number from 0.1 to 0.3, and δ is a number from 0.05 to 0.15). A method for producing a cation partially substituted calcium titanate-supported nickel catalyst.   The method for producing a cation partially substituted calcium titanate-supported nickel catalyst according to claim 4 or 5, wherein the hydrothermal reaction hydrothermal treatment temperature is at most 400 ° C and the reaction pressure is at most 35 MPa.   The method for producing a cation partially-substituted calcium titanate-supported nickel catalyst according to claim 4 or 5, wherein a hydrothermal treatment time of the hydrothermal reaction is more than 0 to 20 seconds.   A synthesis gas comprising a mixed gas of carbon monoxide and hydrogen is obtained from a hydrocarbon and a reforming gasifying agent using the cation partially substituted calcium titanate-supported nickel catalyst according to any one of claims 1 to 3. A method for producing synthesis gas characterized by the above.