Patent ID: 6303099
Filing Date: 2001-10-16
Classification: B01J,C01B,C07D,Y02P,Y10S

Abstract:
A process for producing a pentacyl-type crystalline zeolite, comprising the steps of:(i) preparing a mixture of a silicon compound, water and tetrapropyl ammonium hydroxide,(ii) conducting a hydrothermal reaction of the mixture to obtain a reaction mixture containing zeolite crystals,(iii) separating the zeolite crystals from the reaction mixture to collect a remaining solution,(iv) calcining the resulting zeolite crystals,(v) treating the calcined zeolite crystals with an aqueous solution containing a compound selected from the group consisting of ammonia and ammonium salts to obtain a pentacyl-type crystalline zeolite, and(vi) recycling the solution collected in step (iii) to the mixture preparing step (i),wherein a molar-ratio composition of the mixture prepared in step (i) is adjusted so that the molar ratio of the hydroxide ion to silicon falls within a range of from about 0.1 to about 0.4; that a molar ratio of potassium to silicon is about 0.1 or less; and that an atomic ratio of silicon to the total of aluminum, gallium, boron, titanium and zinc is about 500 or more.