Phosphorus modified HMCM-22: Characterization and catalytic application in methanol-to-hydrocarbons conversion

In this work, a series of phosphorus-modified HMCM-22-x%P samples are prepared by impregnation of HMCM-22 with aqueous solution of (NH4)2HPO4 and subsequent calcination. The phosphorus-modified HMCM-22 samples were characterized by means of XRD, NH3-TPD, and multinuclear (31P, 29Si, 27Al and 1H) MAS NMR techniques. The phosphorus-modified HMCM-22 samples, together with parent HMCM-22, are studied as possible catalysts for methanol-to-hydrocarbons (MTH) reaction. HMCM-22-3%P exhibits very good MTH performance and 100% methanol conversion with ca. 70% selectivity to light olefins can be achieved within time-on-stream of 40 h at 723 K. The MTH reaction over H-MCM-22 and phosphorus-modified HMCM-22 is monitored by in situ UV/Vis spectra, and the hydrocarbon pool species occluded in spent catalysts are analyzed by ex situ GC–MS spectra. Based on the characterization and catalytic results, the modification effects of phosphorus on HMCM-22 and corresponding impacts on the MTH reaction are discussed.

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► Phosphorus modified HMCM-22 characterized by multinuclear MAS NMR.
► Reduction of Brønsted acid sites in HMCM-22 by phosphorus impregnation.
► Enhanced selectivity to propylene in MTH reaction over HMCM-22 by phosphorus modification.