Process for increasing the strength of a zeolite molding

Abstract: A process is disclosed wherein a zeolite molding having a high mechanical strength is produced by contacting a pentasil type zeolite molding with water.

Description: The present invention relates to a process for increasing the strength of a zeolite molding. More particularly, the present invention relates to a process for increasing the strength of a zeolite molding comprising contacting a pentasil type zeolite molding with water. Further, the present invention relates to a use of a zeolite molding in such applications as mentioned below which molding was prepared by contacting a pentasil type molded zeolite with water. Still further, the present invention relates to a zeolite molding containing no substantial amount of a binder and having an increased mechanical strength. A zeolite is a porous crystalline (crystal) containing silicon and oxygen as main components and containing a metal element such as aluminium as a further component according to circumstances. Zeolites have been used for drying and purification of gases, and separation of n-paraffin, n-olefin, and p-xylene taking advantage of their absorption power for gases and liquids. Also, they have been used in many reactions such as decomposition or cracking, hydrogenation, dewaxing, alkylation, dealkylation, and isomerization taking advantage of their catalytic ability in those reactions. Zeolites are used usually after being molded into pellets by an extrusion molding or tablet molding, or after being molded into fine particles by spray dry molding. However, since zeolites are weak in mechanical strength by themselves, they are molded after being blended with an inorganic binder such as an alumina, silica-alumina, or silica sol. Accordingly, many methods have been proposed for molding a zeolite, such as a method in which a zeolite is blended with an alumina and clay, and then subjected to an extrusion molding (Japanese Examined Patent Publication No. 33-9872 and Japanese Unexamined Patent Publication No. 49-67895), a method in which a mixture of a zeolite with a silica is further blended with water and a base of an alkaline metal as an auxiliary for extrusion molding, and then subjected to an extrusion molding (Japanese Unexamined Patent Publication No. 61-26509), a method in which a zeolite is blended with a silica sol and then treated with ammonium phosphate or the like (U.S. Patent No. 3,846,337), and a method in which a zeolite is blended with water and a silica-alumina, and then subjected to molding to produce a zeolite molded product (Japanese Unexamined Patent Publication, Toku Hyo Hei No. 1-503127). However, when an inorganic binder was used, there has been a defect that the inherent property of a zeolite is diluted, or lowered to a degree corresponding to the amount of the binder, while the mechanical strength of the molded zeolite is increased. EP-A-0403966 and EP-A-0102544 both disclose pentasil type zeolite mouldings which do not contain inorganic binder. However they give no teaching of treatment of the moulding with water or of the conditions of such treatment of the present invention. As a result of continued research, under such circumstances, for increasing the mechanical strength of a pentasil type zeolite molding without using an inorganic binder, it has now been found that the purpose can be achieved by subjecting a pentasil type zeolite molding to such a simple treatment as contacting it with water. An object of the present invention is to provide a process for increasing the strength of a zeolite molding comprising contacting a pentasil type zeolite molding which is free of inorganic binder with water. According to the present invention a process for increasing the strength of a pentasil zeolite molding is characterised in that the pentasil zeolite molding is free of inorganic binder and in that the said molding is contacted with liquid water at 30°C to 100°C for 5 minutes to 10 hours or in that the said molding is contacted with gaseous water at a temperature of 50°C to 200°C for a time of 5 minutes to 72 hours. The pentasil type zeolite molding which can be used in the present invention is a porous crystalline (crystal) material containing silicon and oxygen as main components. It may further contain at least one metal element, such as aluminium, gallium, iron, boron, zirconium, chromium, beryllium, cobalt, lanthanum, germanium, titanium, hafnium, vanadium, nickel, antimony, bismuth, copper and niobium. Particularly, ZSM-5 or ZSM-11 pentasil type zeolite is preferably used in the present invention. Usually, a zeolite having an atomic ratio of silicon to metal elements other than silicon of 10 or more, preferably 100 or more, more preferably 500 or more, is used. Crystalline super silica zeolites can also be used which contain no metal elements but substantially only silicon as constituting elements. Pentasil type zeolites are usually produced by a hydrothermal synthesis and are, if necessary, subjected to, drying, calcination, and ion exchange. Zeolite moldings used in the present invention may be molded from any one of hydrothermal synthesised product, dried product, calcined product, and ion exchange product. In molding of a zeolite, for example, an extrusion, compression, tablet, flow, rolling, or spray molding can be used, and the zeolite can be molded into a desired shape, for example, a shape of a ball, cylinder, plate, ring, or clover leaf shape. When pellet-like moldings are required, extrusion or tablet molding can be used, while when fine particles are required to use as a fluidised bed catalyst, spray drying can be used as the molding technique. The molding can be performed with polyvinyl alcohol, methyl cellulose, polyethylene oxide, or wax added as a further component, as occasion demands. Zeolites having primary particles which are 5 micrometres or smaller across, preferably 1 µm or smaller across are usually used for molding. As explained above, the present invention is characterised in that a pentasil type zeolite is contacted with water, and the water may be in liquid or gas state. Also, presence of a base e.g. an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide or of ammonia, or of methyl amine is desirable and the strength of zeolite moldings can further be increased through the presence of these basic compounds. When an alkali is present together with water in the liquid state, the pH is adjusted usually to 9 or higher and preferably to about 9 to 13. Also, when a base is present together with the water in the gaseous state, a basic gas such as ammonia or methyl amine is generally used as the base. In this case, the basic gas is used in an amount of usually 0.01 to 1 mol, preferably 0.1 to 0.5 mol. A water soluble organic solvent such as methanol or ethanol may be present together with the water. When water in liquid state is used, salts of alkali metals such as hydrochlorides, sulfates, or nitrates of alkali metals may be present. When the zeolite is to be contacted with water, the zeolite is immersed in water, or the water is passed through a column containing the molded zeolites. The temperature of the water is 30 to 100°C and usually 60 to 100°C. The contact time is 5 minutes to 10 hours, and the contact may be repeated as needed. On the other hand, when water in the gaseous state is used, the water in the gaseous state may be passed through a column containing the molded zeolite, or the molded zeolites may be held in an atmosphere of water vapour. The temperature of the water in the gaseous state is 50°C to 200°C, preferably 50°C to 150°C. The contact time is 5 minutes to 72 hours, and the contact may be repeated as needed. After the contact treatment, the zeolite moldings can be washed with water or with an acid such as hydrochloric acid. When washed with an acid, the moldings may further be rinsed with water. Through the steps explained above, the strength of a zeolite molding can be increased, and the molding may further be subjected to calcination, if necessary. According to the present invention, the mechanical strength of a zeolite molding can be increased by subjecting a molded zeolite to such a simple treatment as contacting it with water. In addition, according to the present invention, the mechanical strength of a zeolite molded product can be increased even when an inorganic binder is not used, and thus, the present invention is advantageous in the commercial production of zeolite moldings. Further, the zeolite molding of the present invention has an advantage that its inherent favorable properties will not be impaired since it does not contain an inorganic binder. Thus, the present invention is advantageous even from this aspect. The present invention will now be described in further detail with reference to Referential Examples, Examples, and Comparative Examples. However, it should be understood that the present invention is by no means restricted by such specific Examples. Referential Example 1 In an autoclave having an internal volume of 5 liter and made of stainless steel, 500 g of tetraethylorthosilicate (aluminium content: lower than 10 ppm), 1120 g of a 10 % aqueous solution of tetra-n-propyl ammonium hydroxide, and 1070 g of ethanol were charged, and they were vigorously stirred for 120 min. The pH of the liquid mixture was 13. After the lid of the autoclave was tightened, its contents were subjected to hydrothermal synthesis for 96 hours while keeping the internal temperature of the autoclave at 105°C with stirring at a rotating speed of more than 400 rpm. The internal pressure of the autoclave reached up to 2 or 3 kg/cm 2 during that period of time. The pH of the contents was 11.8 at the time when the hydrothermal synthesis was terminated. The white solids (small particles, primary particle size of zeolite: 0.2 µm) thus obtained were separated by filtration and continuously washed with distilled water until the pH of the filtrate reached approximately 7 to obtain 300 g of a slurry having a solids content of 40 %. The slurry in an amount of 25 g was subjected to filtration and drying to obtain 10 g of white crystalline, solids in powder state. The crystalline solids were analysed by powder X-ray diffraction and identified as pentasil type zeolites. Also as a result of atomic absorption analysis, the content of aluminium in the zeolites and Si/Al atomic ratio were found to be 3 ppm and 147000, respectively. The slurry in an amount of 250 g was concentrated by. using a heating kneader. The water content in the slurry obtained was 47%. The slurry was then kneaded with a kneader until the torque reached 1.2 to 1.4 kg.m, then extruded through a die having a hole diameter of 3 mm, dried in air, and then cut into lengths of 3 mm to obtain moldings. Then, the moldings in an amount of 60 g were subjected to calcination at a temperature of 500 to 530°C for 6 hours under circulation of a mixture of nitrogen and air (volume ratio 1:1) to obtain Solid-A. Referential Example 2 Referential Example 1 was repeated to obtain Solid-A'. Referential Example 3 In an autoclave having an internal volume of 5 liter and made of stainless steel, 500 g of tetraethylorthosilicate (aluminium content: lower than 10 ppm), 1120 g of a 10 % aqueous solution of tetra-n-propyl ammonium hydroxide, and 542 g of water in which 27.6 g of Al 2 (SO 4 ) 3 ·13-14H 2 O was dissolved in advance were charged, and they were vigorously stirred for 120 min. The pH of the liquid mixture was 11.7. After the lid of the autoclave was tightened, its contents were subjected to hydrothermal synthesis for 96 hours while keeping the internal temperature of the autoclave at 105°C with stirring at a rotating speed of more than 400 rpm. The internal pressure of the autoclave reached 2 to 3 kg/cm 2 during that period of time. The pH of the contents was 11.7 at the time when the hydrothermal synthesis was terminated. The white solids thus obtained were separated by filtration and continuously washed with distilled water until the pH of the filtrate was reached approximately 7 to obtain 300 g of a slurry having a solids content of 40%. The slurry in an amount of 25 g was subjected to filtration and drying to obtain 10 g of white crystalline solids in powder state. The crystalline solids were analyzed by powder X-ray diffraction and identified as pentasil type zeolites. As a result of atomic absorption analysis, the ratio of Si/Al was found to be 60. The slurry in an amount of 250 g was concentrated by using a heating kneader. The water content in the slurry obtained was 47%. The slurry was then kneaded with a kneader until the torque reached 1.2 to 1.4 kg.m, then extruded through a die having a hole diameter of 3 mm, dried in air, and then cut into lengths of 3 mm to obtain moldings. Then, the moldings in an amount of 60 g were subjected to calcination at a temperature of 500 to 530°C for 6 hours under circulation of a mixture of nitrogen and air (volume ratio 1:1) to obtain Solid-B. Referential Example 4 In an autoclave having an internal volume of 5 liter and made of stainless steel, 416.7 g of tetraethylorthosilicate (aluminium content: lower than 10 ppm), 931.4 g of a 10 % aqueous solution of tetra-n-propyl ammonium hydroxide, 249.3 g of ethanol, and 0.3 g of titanium tetraisopropoxide were charged, and they were vigorously stirred for 60 min. After the lid of the autoclave was tightened, its contents were subjected to hydrothermal synthesis for 96 hours while keeping the internal temperature of the autoclave at 105°C with stirring at a rotating speed of more than 400 rpm. The white solids thus obtained were separated by filtration and continuously washed with distilled water until the pH of the filtrate reached approximately 7 to obtain 250 g of a slurry having a solids content of 40 %. The slurry in an amount of 25 g was subjected to filtration and drying to obtain 10 g of white crystalline solids in powder state. The crystalline solids were analyzed by powder X-ray diffraction and identified as titanosilicates having a pentasil type structure. As a result of atomic absorption analysis, the ratio of Si/Ti was found to be 3500. The slurry in an amount of 200 g was concentrated by using a heating kneader. The water content in the slurry obtained was 47%. The slurry was then kneaded with a kneader until the torque reached 1.2 to 1.4 kg.m, then extruded through a die having a hole diameter of 3 mm, dried in air, and then cut into lengths of 3 mm to obtain moldings. Then, the moldings in an amount of 40 g were subjected to calcination at a temperature of 500 to 530°C for 6 hours under circulation of a mixture of nitrogen and air (volume ratio 1:1) to obtain Solid-C. Referential Example 5 The hydrothermal synthesis and washing in Referential Example 1 were repeated to obtain 300 g of a slurry having a solids content of 40%. To 250 g of the slurry, 50 g of water in which 4 g of a polyvinyl alcohol was dissolved in advance was mixed, and then the mixture was concentrated by using a heating kneader. The water content in the slurry obtained was 47 %. The slurry was kneaded with a kneader until the torque reached 1.2 to 1.4 kg.m, then extruded through a die having a hole diameter of 3mm, dried in air, and then cut into lengths of 3 mm to obtain moldings. Then, the moldings in an amount of 60 g were subjected to calcination at a temperature of 500 to 530°C for 6 hours under circulation of a mixture of nitrogen and air (volume ratio 1:1) to obtain Solid-D. Referential Example 6 The hydrothermal synthesis and washing in Referential Example 1 were repeated to obtain 300 g of a slurry having a solids content of 40%. The slurry in an amount of 250 g was separated by filtration, and white solids thus obtained were dried at a temperature of 120°C for 16 hours and then pulverized with a ball mill. The pulverized product in an amount of 100 g was mixed with 50 g of water in which 4 g of a polyvinyl alcohol was dissolved in advance, kneaded with a kneader until the torque reached 1.2 to 1.4 kg.m, then extruded through a die having a hole diameter of 3 mm, dried in air, and then cut into lengths of 3 mm to obtain moldings. Then, the moldings in an amount of 40 g were subjected to calcination at a temperature of 500 to 530°C for 6 hours under a circulation of a mixture of nitrogen and air (volume ratio 1:1) to obtain Solid-E. Referential Example 7. The hydrothermal synthesis and washing in Referential Example 1 were repeated to obtain 300 g of a slurry having a solids content of 40%. The slurry was subjected to filtration, and the white solids thus obtained were dried at a temperature of 120°C for 6 hours and then pelletized into particles of 6 to 18 mesh (U.S. Sieve Series) having openings 3.36 mms to 1.0 mms across. The particles were subjected to calcination at a temperature of 500 to 530°C for 6 hours under circulation of a mixture of nitrogen with air (volume ratio 1:1) and then pulverized with a mortar and pestle. The pulverized product in an amount of 80 g was added to 800 ml of a 7.5% by weight agueous solution of ammonium chloride, subjected to ion exchange at a temperature of 70°C for 1 hour, and then separated by filtration. The ion exchange was conducted 4 times in total, then the product was washed with distilled water, dried at a temperature of 120°C, and then further pulverized with a ball mill. The further pulverized product in an amount of 50 g was mixed with 27.5 g of water in which 2 g of a polyvinyl alcohol was dissolved in advance, kneaded with a kneader until the torque reached 1.2 to 1.4 kg.m, extruded through a die having a hole diameter of 3 mm, dried with air, and then cut into lengths of 3 mm to obtain Solid-F. Referential Example 8 The hydrothermal synthesis and washing in Referential Example 1 were repeated to obtain 300 g of a slurry having a solid content of 40%. The slurry in amount of 250 g was separated by filtration, and the white solids thus obtained were dried at a temperature of 120°C for 16 hours and then pulverized with a ball mill. The pulverized product in an amount of 100 g was mixed with 50 g of water in which 4 g of a polyvinyl alcohol was dissolved in advance, kneaded with a kneader until the torque reached 1.2 to 1.4 kg.m, then extruded through a die having a hole diameter of 5 mm in which a needle having a diameter of 2 mm was arranged, dried in air, and then cut into lengths of 5 mm to obtain ring like moldings having an outside diameter of 5 mm and an inside diameter (hole diameter) of 2 mm. Then, the moldings were subjected to calcination at a temperature of 500 to 530°C for 6 hours under circulation of a mixture of nitrogen and air (volume ratio 1:1) to obtain Solid-G. Referential Example 9 The hydrothermal synthesis and washing in Referential Example 1 were repeated to obtain 240 g of a slurry containing 50 % of solid catalysts. The same procedure was further repeated twice, and 720 g of a slurry obtained by mixing the slurries was subjected to a spray drying with an atomizer type spray drier to form fine particles. The average inlet temperature and average outlet temperature of the spray drier were 210°C and 90°C, respectively. Then, 250 g of the white fine particles thus obtained were subjected to calcination in a rotary kiln at a temperature of 500 to 530°C for 6 hours under circulation of a mixture of nitrogen and air (volume ratio 1:1) to: obtain Solid-H. The average particle size of the Solid-H was 80 µm (micrometres). Example 1 In an autoclave, 20 g of Solid-A prepared in Referential Example 1 and 200 g of an aqueous ammonia having a pH of 11.5 and prepared from a 28 % (by weight) aqueous ammonia and distilled water were charged, and they were stirred at a temperature of 90°C for 1 hour. The aqueous ammonia was separated by decantation. This alkali treatment was conducted 3 times in total. Then, the solids were separated by filtration, washed with water, and dried at 120°C for 16 hours to obtain alkali treated moldings. The mechanical strength of the moldings was determined with a Kiya's hardness-meter. An average value of the results of determination for 10 moldings are shown in Table 1. Example 2 Example 1 was repeated to obtain moldings except that 200 g of a liquid mixture having a pH of 11.5 and prepared from 80 g of a 7.5 % (by weight) aqueous solution of ammonium chloride and 120 g of a 28 % (by weight) aqueous ammonia was used instead of aqueous ammonia. The mechanical strength of the moldings was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 1. Example 3 Example 1 was repeated to obtain moldings except that 5 g of Solid-A was used, and 50 g of a 7.5 % (by weight) aqueous solution of ammonium chloride having a pH of 5.8 was used instead of aqueous ammonia. The mechanical strength of the moldings was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 1. Example 4 Example 1 was repeated to obtain moldings except that 20 g of Solid-A' instead of solid-A and 200 g of distilled water instead of aqueous ammonia were used, and the treatment temperature was adjusted to 100°C. The mechanical strength of the moldings was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 1. Example 5 Solid A' in an amount of 5 g was filled in a column (15mm) made of silica glass and heated up to 80°C under circulation of nitrogen gas at 4.2 liter/hr. Then, another nitrogen gas at 4.2 liter/hr accompanied by water prepared by bubbling the nitrogen gas through water kept at 20°C was supplied to the column instead of the nitrogen only. After carrying out the circulation for 24 hours, the gas supplied was changed back to nitrogen gas accompanied by no water and the column was cooled down to 20°C to form objective moldings. The mechanical strength of the moldings was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 1. Comparative Example 1 The mechanical strength of Solid-A obtained in Referential Example 1 was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 1. Comparative Example 2 The mechanical strength of Solid-A' obtained in Referential Example 2 was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 1. Example Strength (kg) Lengthwise direction Crosswise direction Example 1 4.5 4.5 Example 2 4.6 4.5 Example 3 1.0 0.6 Comparative Example 1 0.2 0.1 Example 4 0.9 0.6 Example 5 1.1 0.8 Comparative Example 2 0.2 0.1 Example 6 Example 1 was repeated to obtain moldings except that 20 g of Solid-B obtained in Referential Example 3 was used instead of Solid-A obtained in Referential Example 1. The mechanical strength of the moldings was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 2. Comparative Example 3 The mechanical strength of Solid-B obtained in Referential Example 3 was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 2. Example Strength (kg) Lengthwise direction Crosswise direction Example 6 0.17 0.15 Comparative Example 3 0.05 0 Example 7 Example 1 was repeated to obtain moldings except that 20 g of Solid-C obtained in Referential Example 4 was used instead of Solid-A obtained in Referential Example 1. The mechanical strength of the moldings was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 3. Comparative Example 4 The mechanical strength of Solid-C obtained in Referential Example 4 was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 3. Example Strength (kg) Lengthwise direction Crosswise direction Example 7 4.2 4.0 Comparative Example 4 0.7 0.5 Example 8 Example 1 was repeated to obtain moldings except that 20 g of Solid-D obtained in Referential Example 5 was used instead of Solid-A obtained in Referential Example 1. The mechanical strength of the moldings was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 4. Example 9 Example 8 was repeated to obtain moldings except that 200 g of an aqueous solution of sodium hydroxide having a pH of 11.5 and prepared from sodium hydroxide and distilled water was used instead of an aqueous ammonia. The mechanical strength of the moldings was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 4. Comparative Example 5 The mechanical strength of Solid-D obtained in Referential Example 5 was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 4. Example Strength (kg) Lengthwise direction Crosswise direction Example 8 3.6 3.4 Example 9 5.5 4.4 Comparative Example 5 0.8 0.6 Example 10 Example 1 was repeated to obtain moldings except that 20 g of Solid-E obtained in Referential Example 6 was used instead of Solid-A obtained in Referential Example 1. The mechanical strength of the moldings was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 5. Comparative Example 6 The mechanical strength of Solid-E obtained in Referential Example 6 was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 5. Example Strength (kg) Lengthwise direction Crosswise direction Example 10 12.5 8.0 Comparative Example 6 1.1 1.1 Example 11 Example 1 was repeated to obtain moldings except that 20 g of Solid-F obtained in Referential Example 7 was used instead of Solid-A obtained in Referential Example 1. The mechanical strength of the moldings was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 6. Comparative Example 7 The mechanical strength of Solid-F obtained in Referential Example 7 was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 6. Example Strength (kg) Lengthwise direction Crosswise direction Example 11 4.5 3.0 Comparative Example 7 0.4 0.4 Example 12 Example 1 was repeated to obtain moldings except that 20 g of Solid-G obtained in Referential Example 8 was used instead of Solid-A obtained in Referential Example 1. The mechanical strength of the moldings was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 7. Comparative Example 8 The mechanical strength of Solid-G obtained in Referential Example 8 was determined by the same method as in Example 1. An average value of the results of determination for 10 moldings are shown in Table 7. Example Strength (kg) Lengthwise direction Crosswise direction Example 12 3.4 1.7 Comparative Example 8 0.2 0.1 Example 13 Solid-H obtained in Referential Example 9 in an amount of 60 g was placed in a dish and suspended in an autoclave having an internal volume of 1 liter, made of stainless steel, and having 200 g of water therein. After the lid was tightened, the autoclave was immersed in a constant temperature bath kept at 80°C and allowed to stand for 6 hours. After taking the autoclave out of the bath, it was cooled down to 20°C by leaving the autoclave alone. The fine particles thus obtained were subjected to calcination in a rotary kiln at 500°C for 1 hour under circulation of nitrogen gas to obtain objective moldings. The moldings in an amount of 50 g was fluidized in a column (127 mm and 559 mm long) made of stainless steel by supplying air at 7 liter/hr for 20 hours from the bottom of the column, and the powdering (or degradation) ratio during that time was determined. The result of the determination is shown in Table 8. The powdering ratio was calculated by the following equation, which corresponds to abrasion resistance of moldings. Powdering ratio (%) = [Z/(X -Y)] x 100 wherein X = Total weight (g) of moldings initially filled in a column Y = Weight (g) of powdered fine particles blown from an upper part of a column in the period up until 5 hours after initiation of air blowing Z = Weight (g) of powdered fine particles blown from an upper part of a column during the 5 to 20 hours after initiation of air blowing. Example 14 Example 13 was repeated to obtain moldings except that 200 g of 28 % aqueous ammonia was charged in the autoclave instead of water. The powdering ratio of the moldings thus obtained was determined by the same method as in Example 13. The result of the determination is shown in Table 8. Comparative Example 9 The powdering ratio of Solid-H obtained in Referential Example 9 was determined. The result of the determination is also shown in Table 8. Example Powdering ratio (%) Example 13 2.8 Example 14 2.3 Comparative Example 9 25.5 Reaction Example 1 The moldings obtained in Example 13 in an amount of 5 g were mixed with 50 g of a 5% aqueous solution of ammonium chloride, subjected to ion exchange at a temperature of 60 to 70°C for 1 hour, and then separated by filtration. This ion exchange treatment was repeated 4 times in total, then the crystals thus obtained were washed with distilled water until chloride ions could no longer be detected in the filtrate, and then dried at 120°C for 16 hours. The crystals were further subjected to calcination in a rotary kiln at 500°C for 1 hour under circulation of nitrogen gas to obtain Catalyst-A. The Catalyst-A in an amount of 0.375 g (0.6 ml) was filled in a reaction tube made of silica glass and having an inside diameter of 1 cm and preheated at 350°C for 1 hour under circulation of nitrogen gas at 4.2 liter/hr. Then, a liquid mixture of cyclohexanone oxime/methanol at a weight ratio of 1/1.8 was supplied to the reaction tube at a rate of 8.4 g/hr to react. The space velocity WHSV at that time was 8 hr -1 , and the temperature of the catalyst layer (reaction temperature) was 350°C. Reaction was continued for 7.25 hours. Reaction products were collected every hour while cooling with water and analyzed by gas chromatography. The space velocity WHSV, conversion of cyclohexanone oxime, and selectivity of ε-caprolactam product were calculated by using the following equations, respectively. WHSV (hr -1 ) = O/C Conversion of cyclohexanone oxime (%) = [(X - Y)/X] x 100 Selectivity of ε-caprolactam (%) = [Z/(X - Y)] x 100 wherein O, C, X, and Y are defined as follows: O = Supplying rate of cyclohexanone oxime (kg/hr) C = Weight of catalyst (kg) X = Number of mols of cyclohexanone oxime supplied as a raw material Y = Number of mols of unreacted cyclohexanone oxime Z = Number of mols of ε-caprolactam in the product The results of the reaction are shown in Table 9. Reaction Example 2 Reaction Example 1 was repeated to obtain Catalyst-B except that 5 g of Solid-H obtained in Referential Example 9 was used. Using the Catalyst-B, the same procedures as in Reaction Example 1 were conducted to obtain ε-caprolactam from cyclohexanone oxime. The results of the reaction are also shown in Table 9. Example Reaction time elapsed (hr) 1.25 7.25 Reaction Example 1 Conversion (%) 99.8 99.6 Selectivity (%) 95.0 95.6 Reaction Example 2 Conversion (%) 99.9 99.9 Selectivity (%) 95.6 95.8 The process of the invention provides a pentasil type zeolite in shaped particle form which has increased strength or abrasion resistance. A preferred process of the invention provides a pentasil type zeolite which as a cylindrical moulding of 3mm diameter by 3 mm length has a sum of strength in Kg in the lengthwise direction plus strength in Kg in the cross direction of at least 1.5 kgs, preferably at least 2kgs, 3kgs, 4kgs, 5kgs more preferably at least 6, 7, 8 or 9kgs as measured by a KIYA hardness meter.

Claims: A process for increasing the strength of a pentasil zeolite moulding characterised in that the pentasil zeolite moulding is free of inorganic binder and in that the said moulding is contacted with liquid water at 30°C to 100°C for 5 minutes to 10 hours, or in that the said moulding is contacted with gaseous water at a temperature of 50°C to 200°C for a time of 5 minutes to 72 hours. A process for increasing the strength of a zeolite moulding as claimed in claim 1, characterised in that the pentasil type zeolite moulding has an atomic ratio of silicon to metal elements other than silicon of 10 or more. A process for increasing the strength of a zeolite moulding as claimed in claim 1 or claim 2, characterised in that a base is present together with the water. A process for increasing the strength of a zeolite moulding as claimed in claim 3, characterised in that the base is an alkali metal hydroxide, ammonia, or methyl amine. A process for increasing the strength of a zeolite moulding as claimed in claim 3 or claim 4, characterised in that the water has a pH of 9 or higher. A process for increasing the strength of a zeolite moulding as claimed in claim 3, 4 or 5, characterised in that the amount of the base is 0.01 to 1 mol per 1 mol of the water.

Inventors: KITAMURA MASARU, MURATA SHUZO, TSUCHIMOTO KAZUYA, KITAMURA, MASARU, MURATA, SHUZO, TSUCHIMOTO, KAZUYA
Applicants: SUMITOMO CHEMICAL CO, SUMITOMO CHEMICAL COMPANY LIMITED
Application year: 1993
Main classification: B01J37
IPC codes: B01J29, B01J37