Kinetics of methanol to olefins over AlPO4-bound ZSM-5 extrudates in a two-stage unit with dimethyl ether pre-reactor

The fixed-bed conversion of methanol to olefins was investigated in a two-stage series-flow unit. The first reactor with γ-Al2O3 catalyst converted most of the methanol to dimethyl ether and water vapor (DME pre-reactor). The second reactor produced hydrocarbons and contained an extruded catalyst consisting of H-ZSM-5 (Si/Al = 250) embedded in a novel macroporous matrix of AlPO4 with tridymite structure. Processing experiments were carried out over a wide range of conversions at reaction temperatures from 400 °C to 450 °C, and under variation of the methanol concentrations in the feed between 10% and 34% (v/v). Additional co-feeding experiments with ethene, propene or iso-butene, respectively, delivered insights into secondary reactions. The experimental data were used to develop a kinetic model based on lumps which describes well the MTO reactions at conditions close to industrial practice.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Report on fixed-bed MTO performance of extruded H-ZSM-5/AlPO4 catalysts. ► First kinetic study in a two-stage unit with a DME pre-reactor. ► First kinetic study reporting on feed concentration effects on the selectivities. ► Reaction network supported by co-feeding of ethylene, propylene and iso-butene. ► Kinetic model suitable for conditions close to industrial practice.