Effect of molybdenum oxide loading on hydrodealkylation of C9 + heavy aromatics

摘要

A series of MoO3/HZSM-5 catalysts with different molybdenum oxide loadings were prepared by incipient impregnation method and employed in hydrodealkylation of commercial C9+ heavy aromatics to produce benzene, toluene and xylene (BTX). The catalysts were characterized by means of XRD, N2 adsorption, FT-IR spectroscopy of adsorbed pyridine and NH3-TPD, and the effect of MoO3 loading on structural property and catalytic activity was further studied. It is indicated that catalytic performance in hydrodealkylation of C9+ heavy aromatics relates to dispersion state of MoO3 on HZSM-5 zeolite and acidity of the catalysts ￡?which are affected by the MoO3 loading. The MoO3 species exists as a monolayer dispersion state on the surface of HZSM-5 when the MoO3 loading is less than 15 wt.%. With the MoO3 loading of 15 wt.%, under the conditions of t=460 , ??p=3.0 MPa, WHSV=3.62 h-1 and V(H2):V(C9+)=1600, the conversion of C9+ aromatics and the yield of BTX are 32.44 mol% and 30.98 mol% respectively, and the selectivity of BTX can reach over 95 mol%.