Dry Reforming Of Biogas To Produce Syngas And Its Mechanism

The depletion of fossil fuel and increasing concern about environmental impacts during energy conversion processes have enforce the innovative utilization of renewable energy sources,such as biogas,with relatively low environmental impacts.Dry reforming of biogas can convert two green house gases to valuable syngas,which is beneficial to environment protection.However,several obstacals including high energy consumption,fast catalyst deactivation,and uncertainty of biogas impurities might prevent its further industrial application.Meanwhile,SiCl₄ byproduct from photovoltaic industry has produced in large scale and recycled in poor condition.Thus,a novel low temperature vapor-phase hydrolysis menthod was studied to produce nano-structured SiO₂,which can serve as low-cost and environmentally benign support for catalysts in the biogas dry reforming process.The effects of biogas impurities,including O₂ and H₂S,were studied to prove the adaptability of cheap Ni/SiO₂ applying to biogas dry reforming process.Results showed that nano-SiO₂ with a high specitic surface area of 418 m²·g^-1,a pore volume of 0.84 cm³·g^-1,and an aggregrate particle size of 141.7 nm were obtained through low temperature vapor-phase hydrolysis method after operating condition optimation.SiO₂ synthesized by vapor-phase hydrolysis method had comparable properties with which of flame method,which indicated a high potential for industrial application.Photovoltaic waste-derived SiO₂ was applied as the support for a nickel catalyst in a biogas dry reforming process for the first time,which proved to have high catalytic activity and stability.Comparision with commercial silica indicated that a high pore volume/S_BET ratio benefited the acticity of catalyst.The low O₂ concentration in biogas provided an energy-efficient biogas reforming process with high and stable methane conversions with reduced energy consumption.The inhibited sintering by O₂ was reported for the first time to enhance the stability of catalysts.Sulfur in biogas can cause severe deactivation in biogas reforming with a Ni/SiO₂catalyst,due to the formation of Ni₇S₆,which also cause catalyst sintering and carbon deposition.O₂ activation was proved to be effective in regenerating poisoned catalysts,with the complete elimination of Ni-S species.