Publication: Dimethyl Ether-to-Olefins Conversion

Authors: Marius Kirchmann, Alfred Haas, Christoph Hauber

The Catalyst Review, July 2019, Volume 32, Issue 7 

Conversion of methanol and dimethyl ether to hydrocarbons (MTH) continues to attract significant attention. The process is catalyzed by various zeolites in which the microenvironment (topology and Brønsted acidity) plays a significant role in the product distribution and catalyst lifetime. In the case of the methanol-to-olefins (MTO) reaction, the silica-alumino phosphate SAPO-34 with a chabazite (CHA) framework and small 8-ring pore windows is very selective toward the formation of lower olefins. Linear reaction products can exit, while larger molecules such as branched and aromatic products are retained within the pores leading to the formation of hydrocarbon residues which, in turn, restrict the pores and lead to relatively fast deactivation. However, the high selectivity of SAPO-34 toward lower olefins has led to its successful commercialization in a fluidized-bed reactor-regenerator configuration with continuous regeneration.