A novel mechanism of catalyst deactivation in liquid phase synthesis Gas-to-DME reactions

Abstract

Commercial methanol synthesis catalysts and γ-alumina are stable when used separately in a slurry phase reactor for the methanol synthesis and the methanol dehydration reaction, respectively. However, when they are used as a physical mixture for our slurry-phase synthesis gas-to-DME process, both catalysts deactivate rapidly. Traditional causes of catalyst deactivation, including hydrothermal sintering, leaching, coking, and poisoning, were investigated and subsequently ruled out. Detrimental interaction between the two catalysts was identified as the cause of the rapid, simultaneous deactivation of both catalysts. Intimate solid-state contact between the two catalysts is necessary for this interaction to take place. Most likely, the interaction is due to the migration of Zn-and Cu-containing species from the methanol catalysts to γ-alumina. Although not discussed in this paper, a proprietary dual catalyst system with good stability has been developed.