Production of light olefins from methanol using catalytic fixed bed reactor with different catalytic bed composition

Abstract

Methanol to olefin conversion has captured the attention of the industry as olefins are feed material to many polymer industries. In this work methanol conversion to olefins was investigated over beds of (i) physical mixture of metal oxides with ZSM-5 (PMB) and (ii) metal impregnated over ZSM-5 (MLB). ZSM-5 used in the current study was pre modified by boric acid treatment for modifying catalytic active site composition. Two different metals from alkaline series: calcium and magnesium & from transition metal series: iron and copper were selected. PMB studies were performed on 1:1 (by weight) metal oxides and BZSM-5 whereas for MLB studies, 10 % metal was loaded. Performance studies of the two different bed composition were performed at 500°C, 100 ml/min N2 flow with 1 g catalyst in a fixed bed reactor. 100 % conversion was obtained on MLB studies in presence of Cu, Mg and Fe whereas in PMB studies, 100 % conversion could be obtained over FeO+BZSM-5 bed. The order of olefins yield obtained was in the following order: BZSM-5 > Mg/BZSM-5 > Cu/BZSM-5 > CuO+BZSM-5 > CaO+BZSM-5 > Fe/BZSM-5 > FeO+BZSM-5 > CaO+BZSM-5 > MgO+BZSM-5. It was observed that maximum methane yield was obtained in presence of physical mixture. Gaseous products other than olefins with high composition of C1–C4 hydrocarbons were formed in presence of Mg and Ca whereas the metal impregnated modified-ZSM-5 produced higher content of olefins with Cu loaded catalysts in both bed composition. Metal impregnated catalysts as well as physical mixtures were characterized by BET, FTIR and XRD, FESEM for surface area, topology, crystallinity etc. Spent catalysts were characterized for coke deposition using TGA.