Inspection over carbon deposition features of various nickel catalysts during simulated biogas dry reforming

Abstract

Dry reforming is a promising new technology for biogas utilization. Herein, Ni catalysts using Al2O3, SiO2, MgO, CeO2 and ZnO as supports were prepared and studied to uncover the correlation between physico-chemical properties and activity, also their specific response to carbon formation. The catalysts were characterized systematically via N2-physisorption, XRD, TEM, EDS, H2-TPR, XPS and TGA. The catalytic activity was investigated at 600–850 °C and stability tests were conducted at 750 °C for 12 h. Ni/Al2O3 showed the highest activity with CH4 conversion efficiency due to smaller particle size and stronger metal-support interaction, but seriously plugged the reactor during stability test. Ni/MgO was less active but also had an acceptable CH4 conversion efficiency of 68.8% and conversion rate of 4.70×10−2 mmol/gcat·s at 750 °C. It showed good stability due to the strong metal-support interaction. Ni/ZnO, Ni/CeO2 and Ni/SiO2 showed poor activity. Detailed carbon deposition feature analysis of spent catalysts illustrated that Ni/Al2O3 had the most carbon deposition as filamentary and graphitic species. Ni/CeO2 mainly showed filamentary carbon, while Ni/MgO, Ni/ZnO and Ni/SiO2 bore little carbon during stability tests. Ni/MgO seems a suitable candidate in dry reforming reaction which can reach the balance of activity, stability and carbon resistance.