MSU-S_(MFI)和MCM-41的催化裂化及烷基化活性比较

Comparison on the Catalytic Cracking and Alkylation Activities between MSU-S_(MFI) and MCM-41 Aluminosilicates

以MFI沸石前驱体作为基本结构单元组装介孔硅铝分子筛MSU-SMFI.XRD和氮气吸附数据表明MSU-SMFI具有类似MCM-41的六方排列介孔孔道结构,而且其织构参数和以传统方法合成的含铝MCM-41也大体相当.NH3-TPD显示由沸石前驱体组装的MSU-SMFI较硅铝比相同的含铝MCM-41介孔分子筛的固体酸量显著提高.MSU-SMFI上的异丙苯催化裂化转化率比含铝MCM-41提高31%,1,3,5-三异丙苯在MSU-SMFI上也发生了更深的裂解.MSU-SMFI上萘的叔丁基化的转化率比含铝MCM-41提高了15%.以沸石前驱体作为基本结构单元是提高介孔分子筛固体酸性的有效方法.

Mesoporous aluminosilicates MSU-S-MFI with well-ordered hexagonal symmetry were assembled from MFI zeolitic precursors containing abundant protozeolitic nanoclusters. Normal MCM-41 was synthesized by using tetraethyl orthosilicate (TEOS) and sodium aluminate as silica source and aluminum source, respectively. The pore diameter of MSU-S-MFI sample and normal MCM-41 both are 2.70 nm, and their BET specific surface areas and pore volumes are comparable as seen from XRD and N-2 sorption results. Although both MSU-S-MFI and MCM-41 possess weak acidic sites and medium strong acidic sites in NH3-TPD profiles, the density of weak acidic sites and medium strong acidic sites in MSU-Smm are much higher than that of MCM-41. The catalytic cracking conversion of cumene on MSU-S-MFI is 31% higher than that on MCM-41 with the same Si/Al ratio, and the butylation conversion of naphthalene over MSU-Smm is 15% higher than that on the MCM-41 sample. Incorporation of MFI zeolitic nanoclusters into the mesostructured framework of MSU-S-MFI led to enhanced acidity.