Phosphorus-Modified SPP Zeolite Catalysts for Methanol to Propylene Reaction
XING Yaru, LIU Min, GUO Xinwen
State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China
Abstract In order to develop high-performance catalysts for methanol to propylene (MTP) reaction, SPP zeolites with different silica-alumina ratios were prepared, and then treated with phosphorus modification. The pore structure and acid properties of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), inductively coupled plasma (ICP), nitrogen physical adsorption, NH3 temperature-programmed desorption (NH3-TPD) and thermogravimetric analysis (TG). The catalytic performance of each sample was compared in the MTP reaction. The results showed that SPP zeolites had larger specific surface area and pore volume than ordinary ZSM-5 zeolites, which could significantly improve the molecular diffusion rate and the accessibility of active sites, and improve the reaction performance. Due to the pore cleaning effect of weakly alkaline ammonium phosphate, the total pore volume of all samples modified by P increased, and the strong acid content decreased with the increase of the modified P concentration. The MTP reaction catalyzed by SPP zeolite modified with a phosphorus mass fraction of 0.2%, the selectivity of propylene was 50.4%, the selectivity of C= 2-C= 4 was 72.1%, and the coke deposition was 1.4%.
