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)(2)HPO4 and subsequent calcination. The phosphorus-modified HMCM-22 samples were characterized by means of XRD, NH3-TPD, and multinuclear (P-31, Si-29, Al-27 and H-1) 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. (c) 2011 Elsevier Inc. All rights reserved.