| 摘要 |
The present invention relates to a process for the preparation of zeolites having B-CHA framework structure and a composition comprising the molar ratio (n SiO2):B2O3, wherein n is at least 10, the process comprising (i) preparation of an aqueous solution containing at least one source for B2O3, at least one source for SiO2, at least one source of seeding crystals of chabazite structure, at least one organic structure directing agent (SDA) other than Tetramethylammonium hydroxide (TMAOH), acting as a template for the B-CHA structure, and Tetramethylammonium hydroxide (TMAOH), wherein the SDA or mixtures thereof are employed in such amounts that the aqueous solution in (i) exhibits a molar ratio of SDA:TMAOH of 0.01 to 5; (ii) hydrothermal crystallization of the aqueous solution according to (i); wherein B-CHA is essentially free of alkali metal and/or alkaline earth metal and the ratio of the [molar ratio (SiO2:B2O3)] of the gel composition:[molar ratio (SiO2:B2O3)] of the crystalline product having the chabazite structure is greater than 0.5. |
