Operando FT-IR and UV–vis spectroscopic studies emphasise the nature of coke species formed over SSZ-13 zeolite during ethanol-to-hydrocarbons process

Abstract

This study investigates the conversion of ethanol to higher olefins using protonic chabazite (SSZ-13, SiAl = 8) zeolite, employing advanced FT-IR and UV–vis operando spectroscopic techniques, with concurrent mass spectrometry and gas chromatography examinations of the products. The utilisation of varying ethanol loads facilitates the examination of coke production and its progression relative to the feed quantity. The spectroscopic analysis clarifies the species formed on the catalyst's surface, while mass spectrometry and gas chromatography techniques verify the desorbed products. The counterparts in transforming ethanol and methanol to olefins via the recognised intermediates of the hydrocarbon pool mechanism are identified and examined in detail. Significant value-added information is obtained from in situ FT-IR studies complemented by mass spectrometry examination of the gas phase. The MCR-ALS analysis is utilised in spectroscopic operando investigations and offers significant insights into the findings. Furthermore, these investigations are substantiated by chromatographic examination of coke species obtained from spent catalysts.