Dehydration of methanol to light olefins upon zeolite/alumina catalysts: Effect of reaction conditions, catalyst support and zeolite modification

The reaction of methanol to propene was studied in a fixed bed reactor using a pelleted zeolite in alumina matrix support catalyst. The effect of reaction conditions (temperature, pressure, space velocity, feed composition), as well as the effect of support to ZSM-5 zeolite ratio on the conversion of methanol to light olefins (C2-C4) was studied. The best catalyst and optimum reaction conditions leading to a maximum yield of C2-C4 were determined. Use of γ-alumina as support improved the catalyst selectivity to propene and light olefins. Zeolite/alumina catalyst with 25 wt.% ZSM-5 dispersed in a matrix containing 75% alumina led to highest selectivity to propene and light olefins. ZSM-5 zeolite was modified with phosphorus, Cs, Ca and Fe. The effect of their impregnation on the conversion of methanol and selectivity to light olefins was studied. Modification in all cases increased the shape-selectivity to light olefins. ZSM-5 zeolite ion exchanged by Cs led to highest selectivity to light olefins and particularly propene by changing the acid sites distribution.