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

摘要

Modified mesoporous HZSM-5 catalysts were prepared by controlled desilication using a mixture of NaOH and TPAOH (tetrapropylammonium hydroxide) and impregnation of metals (Mn, Ce, and Ba) and metalloid B. The catalytic performances of all prepared catalysts for methanol to propylene (MTP) reaction were evaluated in a fixed bed reactor under atmospheric pressure at 480 extdegree C. The parent and modified catalysts were characterized by XRD, ICP-OES, FE-SEM, NH$_{3}$-TPD, FT-IR, BET, and TGA techniques. The catalyst loaded with 2 wt.% manganese on desilicated HZSM-5 demonstrated the best catalytic performance in terms of the highest selectivity of C$_{2}^{=}$ to C$_{4}^{=}$ olefins (about 93%) 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 mesopores on the zeolite crystals in conjunction with the appropriate acidity.