ИСТИНА

The mechanism of catalyst deactivation in the course of methanol-to-olefins conversion over SAPO-34 catalyst have been studied in slurry and fixed-bed reactors. The carbonaceous deposits accumulated on the catalyst have been investigated by UV/vis, 13C MAS NMR spectroscopy, thermo-gravimetric analysis, as well as GC/MS analysis after dissolution of used catalysts in hydrofluoric acid and extraction of coke by dichloromethane. It has been demonstrated that both in the case of fixed-bed reactor and slurry reactor the main reason of catalyst deactivation is the formation of polyaromatic products. However, the reaction pathways leading to polyaromatic coke are different: in the case of fixed-bed reactor the reaction pathway involves side chain alkylation of metylsubstetuted aromatics with methanol, whereas in the case of slurry-reactor it includes alkylation with olefins.