Mechanistic study of non-thermal plasma assisted CO2 hydrogenation over Ru supported on MgAl layered double hydroxide

Abstract

Carbon dioxide (CO2) hydrogenation to value-added molecules is an attractive way to reduce CO2 emission via upgrading. Herein, non-thermal plasma (NTP) activated CO2 hydrogenation over Ru/MgAl layered double hydroxide (LDH) catalysts was performed. The catalysis under the NTP conditions enabled significantly higher CO2 conversions (∼85 %) and CH4 yield (∼84 %) at relatively low temperatures compared with the conventional thermally activated catalysis. Regarding the catalyst preparation, it was found that the reduction temperature can affect the chemical state of the metal and metal-support interaction significantly, and thus altering the activity of the catalysts in NTP-driven catalytic CO2 hydrogenation. A kinetic study revealed that the NTP-catalysis has a lower activation energy (at ∼21 kJ mol−1) than that of the thermal catalysis (ca. 82 kJ mol−1), due to the alternative pathways enabled by NTP, which was confirmed by the comparative in situ diffuse reflectance infrared Fourier (DRIFTS) coupled with mass spectrometry (MS) characterisation of the catalytic systems.