Effect of reaction conditions on methanol to gasoline conversion over nanocrystal ZSM-5 zeolite

Abstract

A nanocrystal ZSM-5 zeolite comprising uniform single crystal particles of ∼100 nm in size was synthesised and characterised using XRD, ICP–AES, SEM, TEM, solid state MAS NMR and nitrogen physisorption techniques. The catalytic performance was tested in methanol to gasoline (MTG) conversion with a particular focus on the effect of reaction conditions, namely, temperature from 300 to 450 °C, pressure from 0.1 to 2.0 MPa and WHSV from 1 to 4 h−1. Temperature showed a significant impact. At temperatures ≤350 °C, methanol conversion did not complete while the catalyst was deactivated more rapidly. Increasing temperature to above 375 °C saw complete methanol conversion and durable catalyst activity. Further increasing the reaction temperature to above 400 °C reduced gasoline yield. Pressure mainly affected the product selectivity; a higher pressure led to a lower C1–C4 selectivity but enhanced durene formation. Further increasing pressure also favoured coke formation, leading to faster loss of catalyst activity. Likewise, increasing WHSV reduced C1–C4 selectivity but promoted the formation of durene and coke, resulting in a rapid deactivation of the catalyst. The optimal reaction conditions for this nanocrystal ZSM-5 catalyst in MTG were found to be 375 °C, 1.0 MPa and WHSV of 2 h−1.