2/Al 2O 3 ratio and catalytic performance in the methanol-to-olefins reaction]]>

摘要

AbstractA hierarchical ZSM-11/5 composite zeolite with a high SiO2/Al2O3ratio was successfully synthesized using a seed-induced method in the presence of cetyltrimethylammonium bromide, characterized by scanning electron microscopy, X-ray diffraction, X-ray fluorescence,27Al NMR,27Si NMR, N2physical adsorption, and temperature-programmed desorption of ammonia, and studied in the frame of the methanol-to-olefins reaction. The results show that the amount of seed added plays a pivotal role in the formation of hierarchical ZSM-11/5 composite zeolite. With an increase in the amount of seed, the composite zeolite exhibits excellent catalytic performance in the methanol-to-olefins reaction, which can be attributed to the higher specific surface areas, higher external surface areas, more mesopore volumes, and more acid sites than ZSM-11 synthesized by the conventional method with tetrabutylammonium ions as a template. Contrary to the conventional point of view, the addition of too much seeds results in a dramatic decrease in the catalytic performance, which is ascribed to the higher proportion of ZSM-5 in the ZSM-11/5 composite zeolite.]]>