Selective Production of Propylene from Methanol over Monolith-Supported Modified ZSM-5 Catalysts

The catalytic activity of ZSM-5 zeolites with a SiO2/Al2O3 molar ratio of 30, 50, 80, 280, and 410 was investigated in a fixed bed continuous flow reactor system and was found that the ZSM-5 zeolite with SiO2/Al2O3 molar ratio of 280 (HZ-280) exhibited best catalyst performance. The optimized reaction conditions achieved were 500 °C, 1 bar pressure, and weight hourly space velocity of 15 h–1 using methanol as feed. At optimum reaction conditions, HZ-280 exhibited propylene selectivity of 47.3% and propylene yield 17.4% with 100% methanol conversion. HZ-280 zeolite was modified with P, Ce, Fe, and La to select the best promoter to enhance propylene selectivity and yield. The best-modified catalyst obtained was HZ-280 with 0.1 wt % phosphorus loading, which further improved propylene selectivity by 14% and yield by 24.7%. Then, the monolith structured catalysts were prepared by single-layer (6.8%), double-layer (10.3%), and triple-layer (13.1%) coating of HZ-280 catalyst. HZ-280 single-layer-coated monolith...