(NH4)2SiF6处理对KL沸石孔分布的影响

EFFECT OF (NH 4) 2SiF 6 TREATMENT ON TEXTURAL PROPERTIES OF KL ZEOLITE

The pore size distribution and crystallinity of KL zeolite treated with ammonium hexafluorosilicate (AFS) are dependent on the preparation conditions. It is shown that with increasing amount of AFS added, the volume of micropores decreases, the volume of mesopores increases, the average pore size decreases slightly and the crystallinity of samples becomes poor. Both good crystallinity and larger mesoporous volume are achieved by lowering the speed of adding AFS solution into reaction slurry. The presence of ammonium acetate buffer solution leads to a sharper size distribution of mesopores and a relatively high crystallinity, together with a decrease in mesoporous volume. A properly long aging time also favors the centralization of pore size. It seems that dealumination of zeolite KL to greater than 50% is very difficult.