Synergistic co-conversion of pentane and methanol to aromatics over bifunctional metal/ZSM-5 zeolite catalysts

Abstract

The co-aromatization of pentane and methanol not only realizes a heat coupling effect, but also enhances the production of aromatics possibly by a synergistic reaction. In this work, a series of metal (Zn, Ag, Ni, La, Fe and Cu) modified ZSM-5 zeolite catalysts have been prepared by impregnation and evaluated for n-pentane and methanol co-conversion. By systematically analyzing the acidic properties and catalytic performance of these metal/ZSM-5 zeolite catalysts, the bifunctional nature of the active center was probed. The synergistic conversion between n-pentane and methanol was verified by the greatly improved selectivity to aromatics compared with their separate reactions. The co-aromatization mechanism was further explored and concluded as two aspects: one was the methylation of olefinic reaction intermediates to larger molecules easily transforming to aromatics, the other was the alkylation of benzene and toluene to xylenes by methanol. In addition, a fluidized bed co-aromatization process was proposed for future commercialization, and its application in the petroleum refining and coal chemical industries is predicted.