Comparison of two methods of iridium impregnation into HZSM-5 in the methanol to propylene reaction

In this paper, the effects of two methods of iridium impregnation into HZSM-5 on catalyst stability, selectivity for propylene and byproducts in the conversion of methanol to propylene (MTP) were investigated in a continuous flow isotherm fixed-bed reactor. XRD, BET surface area, NH3-TPD and ICP-AES analytical techniques were applied to define the physical and chemical characteristics of zeolites. The reaction was conducted at 480 °C and 1 bar with WHSV = 1 h−1, and with an equal weight percent of methanol and water in the feed. The results revealed that iridium impregnation into HZSM-5 powder led to enhanced propylene selectivity (8%) and catalyst stability while iridium impregnation into extruded HZSM-5 drastically decreased catalyst lifetime.

Highlight
► A comparison between two methods of HZSM-5 impregnation by iridium
► Effect of presence of iridium metal on propylene selectivity in MTP reaction
► Increasing the methanol conversion by iridium incorporation into the zeolites
► Inefficacity of iridium incorporation into extruded HZSM-5
► Effectiveness of iridium incorporation into extruded zeolite