| 摘要 |
PURPOSE:To improve heat resistance of the subject zeolite by replacing Al in a zeolite crystal structure with one or more kinds of elements selected from P and V and forming a structure containing these element in a specific amount. CONSTITUTION:Hydrochloric acid is added to water in which a zeolite such as ZSM-zeolite is immersed to give about 5N aqueous solution of hydrochloric acid and the solution is heated to about 90 deg.C and stirred for about 20 hr at the same temperature and then cooled to room temperature and the zeolite is washed until the pH becomes about 4 and the solution is dried to prepare an acid-treated zeolite. An aqueous solution of vanadyl sulfate having a prescribed concentration is added to zeolite dealuminated by this acid treatment and the solution is heated to about 90 deg.C and stirred for about 20 hr to bind two O<-> anions in H-eliminated position of the zeolite to VO<2+>. After the reaction. the reactional liquid is filtered with suction and a solid is washed and dried and fired at about 400 deg.C so as to form V-O bond to provide the heat resistant zeolite containing >=0.01wt.% V element in the crystal structure. The acid-treated zeolite is treated with hypophosphorous acid in the same manner so as to form P-O bond in the crystal structure to provide another heat resistant zeolite containing >=0.01wt.% P element. |
