JPH11514291A - Honeycomb catalyst carrier - Google Patents

Abstract

(57) Abstract: mainly discloses a honeycomb X-ray amorphous catalyst support consisting of SiO _2, the catalyst carrier is calcined to then acid leaching, the pore volume and about 0.1~1.2ml / g A phyllosilicate having a specific surface area (according to BET) of about 20 to 400 m ² / g and at least one of amorphous silicic acid or amorphous aluminum silicate of about 10 to 50% by weight; And the ratio of wall thickness to wall spacing is 1: 5 to 5: 1. The catalyst support, 10 m ² / g or more, preferably liquid phyllosilicate was finely pulverized with a specific surface area of 40~500m ² / g, preferably into a paste with water, extruding the said paste into honeycomb bodies, it It is prepared by drying and firing at a temperature of about 50 to 200 ° C., which is lower than the sintering temperature of the corresponding silicon oxide of aluminum silicate, and then subjecting the fired body to an acid treatment. The catalyst support includes at least one element having a catalytic action of Group 1A, 1B, 2A, 2B, 6A and / or Group 8 of the periodic table. The catalyst can be used for the preparation of unsaturated esters from olefins, acids and oxygen in the gas phase, the purification of exhaust gases, including organics, and the alkylation of aromatics, especially the preparation of ethylbenzene from benzene and ethylene.

Description

Description: TECHNICAL FIELD The present invention relates to a honeycomb catalyst carrier, a catalyst prepared thereon, a method for preparing the catalyst carrier, and a method for using the same. Honeycomb catalysts have been used in various technical catalytic processes which are processed in the gas phase. Despite having a larger surface area, the resistance to flow is very low compared to fixed bed catalysts. This is why it is used in a wide range of applications, especially those involving high flow rates. In particular, honeycomb catalysts are used in exhaust gas purification systems of automobiles and power plants. In the preparation of a honeycomb catalyst for an automotive exhaust purification system, first, a ceramic honeycomb catalyst carrier is extruded. A conventionally used ceramic material is cordierite. The ceramic catalyst support is baked at a temperature of 1000 ° C. or higher and then compressed. When prepared in this manner, the carrier has few openings. For this reason, the specific surface area is very small. In order to evenly distribute the catalytic noble metal over the largest possible surface area, the fired and then pressed honeycomb catalyst is coated with what is called a wash-coat [Wash-Coat]. The cleaning-coating generally consists of gamma-aluminum oxide and is applied to the honeycomb catalyst by impregnation. In a second heat treatment step, the cleaning-coating is impregnated with a water-soluble noble metal salt and then reduced under application conditions. The above-mentioned catalysts coated with noble metals have a number of disadvantages. Since the cleaning-coat and the ceramic carrier are made of different materials, the thermal strain causes the cleaning-coat to peel off. In addition, the catalytically active surface area of such catalysts is very small, since the honeycomb supports used are not porous. EP-B-0211224 and DE-A-3524160 disclose catalysts for reducing nitrogen oxides in combustion exhaust, which contain phyllosilicate as a catalyst component, but have a multilayer structure, for example a three-layer silicate. No acid activated phyllosilicates having the formula: Firing and acid impregnation after firing are not specified. Also, the catalysts disclosed in EP-B-0 211 224 and DE-A-3524160 can be prepared in the form of a honeycomb, but no data is given on the structure of the honeycomb. DE-A-4326938 discloses a honeycomb ceramic catalyst for the oxidation of hydrocarbons and halogenated hydrocarbons, which has an additive of phyllosilicate as a carrier component and a ternary oxide as a catalytic component. . However, the addition of amorphous silicic acid or amorphous aluminum silicate is not disclosed. Also, there is no disclosure of impregnation after firing and the structure of the honeycomb body. DE-A-4405877 discloses a shaped catalyst support based on catalysts, in particular on at least one acid-activated phyllosilicate, which comprises porous silica and / or ganite on silicate. This compact is not X-ray amorphous, and neither firing nor acid impregnation after firing is specified. The specific structure of the molding is not disclosed. DE-A-4405878 relates to a method for preparing a granular adsorption medium, comprising drying an acid-activated phyllosilicate, pulverizing it finely, moistening it with water and then kneading it under agglomeration conditions. . Dried granules prepared by finely grinding and drying the agglomerates have improved abrasion resistance. DE-A-2908491 discloses a process for the preparation of a catalyst for hydrogenating olefins to alcohols, in which in a first step the montmorillonite clay is first treated with an acid, press-molded, and then 500-. It is characterized by firing at 800 ° C. The resulting shaped carrier material is treated with an acid in a second step. In the third step, the spherical support is converted to an acid catalyst by impregnation with acetic acid. However, no honeycomb catalyst is prepared by this method. A similar method is disclosed in DE-A-4107973, which adds silica gel to acid-treated clay. However, this method is also not used for preparing the honeycomb catalyst. The present invention is based on the problem of providing a catalyst carrier having an optimal porous structure that can be converted into a catalyst by an appropriate treatment. According to the present invention, primarily honeycomb X-ray amorphous catalysts made of SiO ₂ is fired to then acid leaching, the pore volume and about 20 to 400 m ² / g to about 0.1~1.2ml / g A phyllosilicate having a specific surface area (according to BET) and at least one of amorphous silicic acid or amorphous aluminum silicate up to about 10 to 50% by weight, having a wall thickness of about 0.1 to 5 mm And the ratio of wall thickness to compartment size is 1: 5 to 5: 1. Honeycomb catalyst carrier has a bulk density of 0.8 to 2.0 g / cm ^3. The expression "mainly composed of SiO ₂ " means that the catalyst support contains about 50% or more of free SiO ₂ not bound in the silicate. The specific surface area of the honeycomb catalyst carrier is suitably in the range of about 70~400m ² / g. The surface area per volume is about 10 × 10 ³ m ² / l or more, preferably about 20 × 10 ^{3 to} 20 × 10 ⁴ m ² / l. "Surface area per volume" is the surface area related to the volume of the honeycomb body, for example, the volume of the reactor when the honeycomb body is completely filled in the reactor. The average pore size of the catalyst support is preferably in the range of about 5 to 100 nm. Pore volume and average pore size were determined by the mercury penetration method according to ASTM T4284-83. Mercury was passed through the samples to be tested at room temperature. The porosimeter measured the amount of mercury passed versus the pressure. In view of the negative wetting angle between mercury and the sample surface, the smaller the hole, the higher the pressure. Using a test apparatus (Micrometrics Pore Sizer 9310), for pore sizes up to 5 nm, the pressure range is 1 to 3000 bar. The pore size distribution can be determined based on the correlation between the amount of permeating mercury and the value of the pressure used. The specific surface area by BET can be determined according to DIN 661 32 (sligle-point nitrogen method) using samples heated to 250 ° C. The acidity of the catalyst support of the present invention is preferably at least 10 μg equivalent / g. The acidity is determined as follows. The finely ground catalyst support (1 g) was accurately weighed and dispersed in 100 ml of distilled water. The dispersion was then stirred for 15 minutes. Next, the suspension was titrated by an automatic titration processor [Titroprocessor] 686 manufactured by Merthrom using a 0.01 N natron alkali solution [natron lye] to a value of pH 7.00. The acidity was determined by the equivalent of the used natron alkaline solution [natron lye]. The acidity was expressed in μg equivalent / g. According to the invention, the honeycomb catalyst support is further based on the catalyst support described above and comprises at least one element having catalytic activity of group 1A, 1B, 2B, 6A and / or group 8 (former IUPAC term). Prepare by incorporating. Group 1A includes, for example, potassium, Group 1B preferably includes copper, silver and gold, Group 2B preferably includes zinc and cadmium, Group 6A preferably includes chromium, molybdenum and tungsten, Group VIII preferably includes ruthenium, rhodium, palladium and platinum. According to the invention, an acid can be further added. According to the present invention, a process for the preparation of the above-mentioned catalyst carrier, 10 m ² / g or more, preferably liquid phyllosilicate was finely pulverized with a specific surface area of 40~500m ² / g, preferably a paste with water Extruding the paste into a honeycomb body, drying the paste, firing at a temperature of about 50 to 200 ° C. which is lower than the sintering temperature of the corresponding silicon oxide of aluminum silicate, and then subjecting the fired body to an acid treatment. A method for preparing a catalyst carrier is provided. The catalyst support is preferably prepared from a phyllosilicate containing at least 10% by weight of impregnable divalent or trivalent metal ions (such as Ca, Mg, Al, Fe ions). It is preferable to use phyllosilicates described below; montmorillonite, hectorite, sapolite, stevensite, sepiolite, attapulgite, vermiculite, beidellite and / or kaolin. The finely ground phyllosilicate preferably has a particle size of about 100 nm to 100 μm. Synthetic silicate salts and / or pure silicic acid can be added to the lye-treated phyllosilicate to control the desired properties of the product. The process of the invention makes it possible to prepare a honeycomb catalyst support having a highly specific and geometric surface, which also has good mechanical strength. The catalyst exhibits catalytic action when used as the above-mentioned exhaust gas purifying catalyst. The catalyst support preferably comprises at least one catalytic element and a promoter element selected from groups 1A, 1B, 2B, 6A or group 8 (previously defined) of the periodic system. The catalyst carrier is preferably impregnated with a salt solution of a noble metal (Ru, Rh, Pd, Pt), dried, and then calcined. Preferably, the compact is dried (at a temperature of 50-100 ° C) and fired at about 200-600 ° C. The porous honeycomb catalyst carrier of the present invention is preferably used in a chemical method in which the synthesis is carried out completely in the gas phase. Examples are the synthesis of vinyl acetate and the afterburning of air containing organics, such as petroleum refining varnishes and tackifier production and plants for removing halogenated organic compounds in a harmless manner. According to the present invention, the catalyst of the present invention is used for the preparation of unsaturated olefins from olefins, acids and oxygen in the gas phase, and for the purification of air, including organics, and the alkylation of aromatics, in particular ethylbenzene from ethylene and benzene. Can be used as a catalyst in the preparation of An economically effective method for the preparation of vinyl acetate throughout the world is gas-phase acetoxylation of ethylene. A gaseous mixture of ethylene, acetic acid, oxygen and nitrogen (as a compound gas) provides a stream to the tubular reactor. The reaction is carried out at a pressure of 8 to 10 bar (Weissermel, Alpe Industrielle Organische Chemie VCA Verlagsgesellschaft Weinheim, Vol. 3, 1990, 244- See page 247). The possibility of an explosion is avoided by adjusting the oxygen content in the starting mixture. Ethylene conversion is usually about 10%. The process is carried out using a prior art solid bed catalyst with a noble metal coated SiO ₂ support. Accordingly, Jute-Chemie AG has produced a spherical silicate support "KA-Traeger" based on acid-activated bentonite. Commercial catalysts have particle sizes in the range of 5-7 mm. Prior art methods include impregnating SiO ₂ with palladium acetate, cadmium acetate and potassium acetate in glacial acetic acid, and then drying at 100 ° C. under reduced pressure. Reduction of the metal salt can be performed using hydrogen or other suitable reducing media. In particular, it is preferable to carry out an improved method using a water-soluble gold compound, and to carry out reduction after precipitation. DE-A-3803800 discloses a cylindrical carrier with a convex end face, wherein 50% of the pore system has pores of 50-20 nm. The carrier material consists of aerogenous SiO ₂ or an aerogenous mixture of SiO ₂ and Al ₂ O ₃ . Carriers are identified by excellent space / time rates as well as by a high degree of selectivity. In the process for producing vinyl acetate disclosed in DE-A-3940125, a SiO ₂ carrier or SiO ₂ having a particle size of 4 to 9 nm and a pore size of 7 to 10 nm but having a pore volume of 50 to 90%. -al ₂ O ₃ carrier is employed. The catalyst is prepared by impregnation with palladium, cadmium and potassium salts, followed by reduction. All of the above-mentioned catalysts for vinyl acetate synthesis have common drawbacks: impregnation with metal gives rise to an overall cross-section of the catalyst support. In order to promote selectivity to vinyl acetate and to suppress side reactions of ethylene oxidation, it is necessary to shorten the contact time with the catalyst in the reactor. Due to the relatively long diffusion path inside the catalyst body, the reaction time is lengthened, thereby causing the formation of by-products. The use of catalysts having a substantially small diameter of 5-6 mm is disadvantageous because of the high pressure drop. Attempts to eliminate the above disadvantages have been made in DE-A-4120492 by performing shell metal impregnation of the catalyst supports of DE-A-3940125 and DE-A-3803900. According to this patent application, impregnation can be limited with a mineral acid to obtain a coating of metal on the outer shell of the catalyst support. This can achieve higher selectivity. However, this method is incomplete because only a portion of the surface available in the reactor is catalytic. This is unacceptable as the space / time speed is low, which reduces the economic efficiency of the method. The use of the catalyst according to the invention is described as applied to the synthesis of vinyl acetate as well as to the purification of exhaust gases containing organic matter. The following example shows a comparison between a porous honeycomb catalyst and a prior art catalyst. As with other chemical methods using catalysts for vinyl acetate synthesis, trans fer occurs with higher space / time velocities that combine higher selectivity at lower resistance to flow . This transition occurs even in an ideal method using the porous honeycomb catalyst of the present invention. The porous honeycomb catalysts or catalyst supports mainly consisting of SiO ₂ according to the invention are particularly suitable for reactions in the presence of acids. Typical carrier materials, such as γ-Al ₂ O _3, are damaged by the acid component. In contrast, the catalyst support of the present invention is not damaged by the acid. For this reason, the catalysts or catalyst supports of the invention are particularly good for the decomposition of chlorinated organic compounds. When the wall thickness of the honeycomb catalyst is 5 mm or less, the cross section of the carrier is entirely coated with a catalytic metal. In this regard, the catalyst has the advantage that the overall catalytic surface can be utilized and the diffusion path is shorter. This results in high space / time velocities, with high selectivity in the manufacturing method. All of the above powder phyllosilicate can acid impregnation is from about 20 to 500 m ² / g, and preferably have a particle size surface area and about 100nm~100μm about 40~500m ² / g, synthetic phyllosilicates As well as pure silicic acid. In preparing the catalyst support, the powdered silicate is mixed with an appropriate amount of a liquid, preferably water, to form a paste. The resulting paste is extruded by a suitable extrusion die into a honeycomb body of the desired configuration. Body Suitable organic and inorganic adhesives can be added to increase. The desired effect in the porous system is achieved by adding combustible materials such as metals, graphite, polyethylene microspheres, cellulose ethers and cellulose fibers together with catalytic oxides. The extruded honeycomb body is preferably pre-dried (e.g., at a temperature below 100C) and fired at a temperature of about 20-200C, which is below the sintering temperature of the material used. Usually, the firing temperature (depending on the material used and the application) is between 400 and 1600C. After firing, the honeycomb body is impregnated with an acid, preferably hydrochloric acid, to control the pores. After calcination and impregnation with a mineral acid, coating with a catalytic substance such as a noble metal salt is carried out in a conventional manner. Preferred noble metal salts are platinum, palladium, rhodium and iridium salts. It is preferred to use a suitable organic acid salt (eg, acetate). Salts of promoter elements such as cadmium, barium and potassium can be further added. After impregnating the support with the noble metal salt solution, the impregnated support is dried and then calcined at about 200-600 ° C. Convert precious metal salts to precious metals. Noble metal salts of inorganic acids such as chloride (or chloro-complex) can also be used. In this case, the oxide or hydroxide of the noble metal is precipitated on the carrier with ammonia. The resulting carrier is dried and then reduced with a suitable reducing medium (eg, hydrogen). The coated catalyst body preferably has a diameter of 10 to 50 mm and a ratio of wall thickness to wall spacing of 1: 5 to 5: 1. The wall thickness is 0.5-5 mm. The length of the honeycomb catalyst can be arbitrarily selected and has no effect on the characteristics of the present invention. In consideration of implementation, the length of the honeycomb catalyst is 50 cm or less because of the possibility of breakage. The present invention will be described with reference to the following examples. Comparative Test Example 1 Finely pulverized pyrogenic silicic acid (90 parts by weight) (Aerosil® 200, manufactured by DEGUSSA) was homogenized together with 10 parts by weight of magnesium stearate to form a paste-like mixture. Then, water was added to the pasty mixture in an amount necessary to obtain good granular particles having a particle size of 0.1 to 1 mm. Good particles were dried and a fraction of 0.1-0.5 mm was selected. The dried particles were wetted with 15 parts by weight of water, and a tablet having a convex end face having a diameter of 6 mm and a diameter of 6 mm or more was pressed with a tableting press. The pressed tablet was dried at 90 ° C. for 12 hours and baked at 900 ° C. for 4 hours. The fired tablet (100 g) (porous carrier) is impregnated with a solution of 11.5 g of palladium acetate, 10.0 g of cadmium acetate and 10.8 g of potassium acetate in 66 ml of glacial acetic acid and then the remaining solution Was dried under nitrogen at 60 ° C. under a pressure of 200 mbar to a content of 2% by weight. This had a palladium content of 2.3% by weight, a cadmium content of 1.8% by weight and a potassium content of 2.0% by weight. Comparative Test Example 2 The calcined SiO ₂ support prepared as in Comparative Test Example 1 was impregnated by contact with a metal salt in 10% hydrochloric acid for 8 hours at room temperature, washed with running water to remove chlorine, and then dried. Was. Impregnation with metal salts was carried out as described in Comparative Test Example 1. Comparative Test Example 3 The calcined SiO ₂ support prepared as described in Comparative Test Example 1 was impregnated by contact with a metal salt in 10% hydrochloric acid for 14 hours at room temperature, washed with running water to remove chlorine, and Dry at 110 ° C. for 5 hours. 1. The resulting carrier (100 g) (the carrier includes porosity) It was impregnated with a solution of 8 g of sodium tetrapalladium chloride and 0.7 g of hexachlorogoldacid and then dried. The dried and impregnated carrier was then transferred to 500 ml of a 2% aqueous sodium hydroxide solution, allowed to stand in this solution for 30 minutes, and then washed with deionized water to completely remove the chloride. The wet carrier was dried again. The carrier was then impregnated with 7.0 g of an aqueous solution of potassium acetate. The impregnated support was dried at 100 ° C. The resulting catalyst contained 1.0% by weight palladium, 0.4% by weight gold and 2.8% by weight potassium. Example Preparation of a Honeycomb Catalyst (According to the Invention) Acid-activated bentonite containing 73% by weight of SiO ₂ (Tonsil Optimun® FF) having a specific surface area of 240 m ² / g and an average particle size of 12 μm (20 kg) were homogenized in a Drais mixer for 30 minutes with 5 kg of precipitated silica gel (product SD 1164, from Crossfield) having a specific surface area of 330 m ² / g and 15 kg of distilled water. The wet mixture was then extruded into a 25 mm diameter cylindrical honeycomb body having a wall thickness of 1 mm and a wall spacing of 2 mm (square honeycomb). The wet extrudate was dried at 70 ° C. for 12 hours and then calcined at 700 ° C. for 5 hours (the sintering temperature is 900 ° C.). Next, the fired honeycomb body was cut into small pieces having a length of 150 mm. The cut honeycomb bodies were filled in a 50 liter glass reactor and covered with 30% hydrochloric acid. The carrier was impregnated with hydrochloric acid at 90 ° C. for 24 hours. Next, the remaining acid was removed, and the honeycomb body was washed with water to be free of chloride. The X-ray amorphous catalyst support dried at 100 ° C. has a specific surface area of 198 m ² / g and a specific surface area of 0.1 m ² / g. It had a 65 pore volume and an average pore size of 12 nm. The specific surface area per volume was 103 · 10 ³ m ² / l, and the acidity was 25 μg equivalent / g. The honeycomb catalyst carrier (100 g) (catalyst including porosity) was impregnated with a solution of 2.8 g of sodium tetrachloropalladium and 0.7 g of tetrachloroauric acid and then dried. The impregnated honeycomb was coated with 500 ml of a 2% aqueous sodium hydroxide solution and allowed to stand in the solution for 15 hours. The carrier was then washed with water to make it chloride-free and dried again. The dried honeycomb body was impregnated with a solution of 7.9 g of potassium acetate, dried and then calcined at 250 ° C. The resulting catalyst contained 1.0% by weight of palladium, 0.4% by weight of gold and 2.8% by weight of potassium. Usage Example Catalyst activity test The catalysts prepared in Comparative Test Examples 1 to 3 and Examples 1 to 2 of the present invention were placed in a constant temperature tubular reactor having an inner diameter of 26 mm and a length of 6000 mm by placing a spacer ring between individual honeycomb bodies. Filled to have. All tubular reactors contain the same amount of catalyst. The tubular reactor was thermostatted to a temperature of 165 ° C. A gas mixture containing 27% by volume of ethylene, 55% by volume of nitrogen, 12% by volume of acetic acid and 6% by volume of oxygen was passed through the tubular reactor at an inlet pressure of 6.5 bar. Because the reaction was very exothermic, the reactor had to be cooled and maintained at a temperature of 165 ° C. The liquid reaction product was continuously frozen by condensing at 0 ° C. to produce vinyl acetate at a space / time rate. The selectivity was determined by gas chromatography of the reaction gases as well as of the condensed reaction products. The results are shown in the table below.

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Claims (1)

[Claims] 1. Primarily a honeycomb X-ray amorphous catalyst support consisting of SiO _2, the catalyst carrier is calcined to then acid leaching, about 0.1~1.2ml / g pore volume and about ² 0~400m 2 Phyllosilicate having a specific surface area (by BET) of at least one of amorphous silicic acid or amorphous aluminum silicate having a wall thickness of about 0.1 to 5 mm. A honeycomb X-ray amorphous catalyst carrier characterized in that the ratio of wall thickness to wall spacing is 1: 5 to 5: 1. 2. Catalyst carrier of claim 1, wherein the specific surface area is in the range of about 70~400m ² / g. 3. ^3. The catalyst carrier according to claim 1, wherein the surface area per volume is about 10 × 10 ³ m ² / l, preferably about 20 × 10 ³ to 20 × 10 ⁴ m ² / l. 4. The catalyst carrier according to any one of claims 1 to 3, wherein the average pore size is about 5 to 100 nm. 5. 5. The catalyst carrier according to claim 1, wherein the acidity is at least 10 [mu] g equivalent / g. 6. The catalyst carrier according to any one of claims 1 to 5, comprising at least one element having a catalytic action of Group 1A, 1B, 2A, 2B, 6A or Group 8 of the periodic table. Catalyst. 7. A process for preparing a catalyst carrier according to any one of claims 1 to 5, 10 m ² / g or more, preferably liquid phyllosilicate was finely pulverized with a specific surface area of 40~500m ² / g, Preferably, the paste is formed into a paste with water, and the paste is extruded into a honeycomb body, which is dried and calcined at a temperature of about 50 to 200 ° C. which is lower than the sintering temperature of the corresponding silicon oxide of aluminum silicate. A method for preparing a catalyst carrier, comprising subjecting a catalyst carrier to an acid treatment. 8. 8. The method according to claim 7, wherein at least one phyllosilicate is used together with at least 10% by weight of an impregnable divalent or trivalent metal ion. 9. 9. The method according to claim 7, wherein the phyllosilicate used is montmorillonite, hectorite, sapolite, stevensite, sepiolite, attapulgite, vermiculite, beidellite and / or kaolin. Ten. 10. The method according to any one of claims 7 to 9, wherein the finely ground phyllosilicate used has a particle size of about 100 nm to 100 [mu] m. The method for preparing a catalyst according to claim 6, wherein the catalyst carrier according to any one of claims 1 to 5 is a catalyst belonging to Group 1A, 1B, 2A, 2B, 6A, and / or 8 of the periodic table. A method for preparing a catalyst, comprising at least one element having an action. 12． The method of claim 11, wherein the catalyst comprises an acid. 13. 13. The method according to claim 11, wherein the catalyst support is impregnated with a noble metal salt solution, dried, calcined and then the noble metal component is removed. 14. The method according to any of claims 7 to 13, wherein the body is dried and then calcined at a temperature of about 200-600C. 15． The catalyst according to claim 6 and the catalyst prepared by the method according to any one of claims 7-14 are used in preparing an unsaturated ester in the gas phase from an olefin, an acid and oxygen. How to use the catalyst. 16． A method for using a catalyst, comprising using the catalyst according to claim 6 and the catalyst prepared by the method according to any one of claims 7-14 as a catalyst for purifying exhaust gas containing organic matter. 17． Use of the catalyst according to claim 6 and the catalyst prepared by the process according to any one of claims 7-14 as a catalyst in the alkylation of aromatic compounds, in particular in the preparation of ethylbenzene from benzene and ethylene. Use of a catalyst characterized by the above-mentioned.