Dehydroaromatization of methane over doped Pt/Mo/H-ZSM-5 zeolite catalysts: The promotional effect of tin

Abstract

The effect of tin (0.05–s0.2wt.%) on the dehydroaromatization of methane over Pt/Mo/H-ZSM-5 zeolite catalysts was investigated. The 2Mo/H-ZSM-5, 0.5Pt/2Mo/H-ZSM-5 and Sn-modified 0.5Pt/2Mo/H-ZSM-5 zeolite catalysts were prepared by an incipient wetness co-impregnation method and characterized by BET, XRD, H2-TPR, NH3-TPD and TGA-DTG analysis. The addition of platinum increased methane conversion from 4 to 7% and the aromatics selectivity was 65%. A reduction of about 50% in the total amount of carbonaceous deposit occurred when platinum was added to the 2Mo/H-ZSM-5 catalyst. A decrease in methane conversion was observed (from 7.2 to 4.3%) with an increase in the tin loading (from 0.05 to 0.2wt.%). Although the addition of tin decreased the methane conversion, the selectivity towards aromatics increased (64–83%) and a selectivity to benzene above 55% was achieved at 0.1wt.% tin loading. The coke selectivity was reduced from 30 to 15% at low tin loadings (0.05wt.%).