Theoretical Insights into the Effect of the Framework on the Initiation Mechanism of the MTO Process

In this contribution, we investigate the initiation mechanism of the methanol-to-olefins process for the different zeotype materials, H-SSZ-13, H-ZSM-5, H-BEA and H-SAPO-34 using density functional theory. While the energetics differ between these materials, variations are systematic so that the relative ordering of the barriers remains the same. We hence predict that the initiation mechanism follows an identical path in all materials with similar rate-limiting steps. We show that the observed trends that have been found for the reaction barriers can be explained by differences in acidity and van-der-Waals interactions of the materials. [GRAPHICS] .