Insights into CO2 Hydrogenation to DME: In Situ DRIFTS Study of Reaction over Cu/ZSM-5 Catalyst

This study has employed in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to generate mechanistic insights into CO2 hydrogenation to dimethyl ether (DME) via methanol (MeOH) formation followed by dehydration. DRIFTS spectra were captured in situ using low loading Cu/ZSM-5, at temperatures ranging from 100 to 300 degrees C and pressures of 1-25 bar. MeOH peaks were identified at 1005, 1031, and 1056 cm(-1), whereas DME peaks appeared at 1464, 1228, 1192, and 1120 cm(-1). Enhanced selectivity for DME was observed at 25 bar and 250 degrees C, favoring the formate pathway, with monodentate formate peaks at 1482 and 1350 cm(-1). DRIFTS data were collected for CO2 flow only and a 20 % CO2/H-2 mixture (1:4) at 25 bar and 250 degrees C to study the reaction mechanism over time.