Insight into CO 2 reforming of CH 4 via NiO /dolomite catalysts for production of H 2 rich syngas

Abstract

Dry reforming of methane (DRM) over Ni-based catalyst has become very popular way used for the generation of hydrogen rich syngas. In this study, synergetic effect between NiO and high basicity support of dolomite was investigated to determine their activity and stability in DRM process. In this regard, series of monometallic catalyst samples (NiO/Dolomite) at different metal loadings of 5 to 15 wt% of NiO over dolomite support were prepared via wet impregnation method. The catalyst performance evaluation on the production of H2 rich syngas was performed and the obtained results showed that 10 wt% NiO/dolomite catalyst sample recorded the maximum conversion of CH4 and CO2 to H2 at 850°C temperature, 9000 hours−1 g·cat−1 gas hourly space velocity and 0.2 g catalyst loading without in-situ reduction of 5% H2 gas. 10% NiO/dolomite shows better performance on H2 selectivity recording up to 75% and H2/CO ratio of 1:1. The reaction maintained 98% of CH4 and CO2 conversion for up to 10 hours reaction time, with very low coke formation. Non-isothermal reaction of catalyst under CH4:N2 (1:9) proves self-reduced properties of catalyst on dry reforming environment (CH4:CO2) started at 300°C. The prepared catalyst samples were successfully characterized using X-ray photoelectron spectroscopy, temperature-programmed oxidation, field emission scanning electron microscopy, and thermogravimetric analysis to study their physiochemical properties, which could give clue on their activity toward DRM. Kinetic and mechanistic studies prove that DRM reaction of NiO/dolomite catalyst follow dual site associative adsorption of both CH4 and CO2 with bimolecular surface reaction.