Enhanced aromatics selectivity and stability in a coaromatization reaction over P/[ZnCr]/HZSM-5

Abstract

A coaromatization reaction is an effective process for heat-coupling and safety. A comparison study of [ZnCr]/HZSM-5 with P/[ZnCr]/HZSM-5 in the coaromatization of methanol and n-hexane was performed. The relative properties of catalysts were analyzed by means of XRD, FT-IR, py-FTIR, ICP, N₂ sorption, TG, Raman, and so on. [ZnCr]/HZSM-5 showed high selectivity to BTEX but lower stability at high temperature. Meanwhile, P modification tuned the acidity and texture, resulting in a higher BTEX yield of 87.5 wt% and more stability. Moreover, the product distribution was further changed to gaseous C₁–C₃ hydrocarbons and liquid aromatics, which is beneficial to the separation. In addition, the deactivation reasons were also explored. The deactivation reason for [ZnCr]/HZSM-5 is ascribed to both the loss of framework Al_F and the carbon deposit, while for P/[ZnCr]/HZSM-5 it is mainly the carbon deposit.