Synergetic effect of Mn, Ce, Ba, and B modification and moderate desilication of nanostructured HZSM-5 catalyst on conversion of methanol to propylene

Abstract

Modified mesoporous HZSM-5 catalysts were prepared by controlled desilication using a mixture of NaOHand TPAOH (tetrapropylammonium hydroxide) and impregnation of metals (Mn, Ce, and Ba) and metalloid B. Thecatalytic performances of all prepared catalysts for methanol to propylene (MTP) reaction were evaluated in a fixed bedreactor under atmospheric pressure at 480 °C. The parent and modified catalysts were characterized by XRD, ICP-OES,FE-SEM, NH3 -TPD, FT-IR, BET, and TGA techniques. The catalyst loaded with 2 wt.% manganese on desilicatedHZSM-5 demonstrated the best catalytic performance in terms of the highest selectivity of C =2 to C =4 olefins (about93%) and about 52% selectivity of propylene at near 99% methanol conversion in the MTP reaction for a long operation(264 h). The improved catalytic performance can be attributed to the high surface area and the formation of mesoporeson the zeolite crystals in conjunction with the appropriate acidity.