Partial Regeneration of the Spent SAPO-34 Catalyst in the Methanol-to-Olefins Process via Steam Gasification

Abstract

The methanol-to-olefins (MTO) reaction over the SAPO-34 catalyst suffers rapid deactivation due to coke deposition. Here, partial regeneration methods with air combustion and steam gasification were investigated. The results showed that both methods could not only reactivate the spent SAPO-34 catalyst but also prompt ethylene selectivity. Whereas, steam gasification was more effective , by which the initial ethylene selectivity could reach 53%, much higher than that of 23% over fresh SAPO-34 catalyst. Several characterizations, e.g., Fourier transform infrared spectroscopy and gas chromatography–mass spectrometry, indicated that methylated benzenes, which were active hydrocarbon pool species and prompted ethylene selectivity, presented as the main species of residual coke in the SAPO-34 catalyst regenerated via steam gasification. Meanwhile, oxygenated compounds and naphthalene, which could accelerate catalyst deactivation, were observed in the SAPO-34 catalyst partially regenerated via air combustion. Th...