Catalyst and process parameters for the gasification of rice husk with pure CO2 to produce CO

•ZnO is the most active for gasifying rice husk with pure CO2 in the metal oxides used.•650 °C is the optimal temperature of ZnO for catalytic gasification at various calcination temperatures.•The gasification could be affected by temperature, pressure, catalyst loading, space velocity, and rice husk particle size.

A process for preparing CO with CO2 as gasification agent and rice husk as raw material in the presence of metal oxide catalyst was reported in this paper. Five kinds of catalysts (Fe2O3, CoO, NiO, CuO, and ZnO) supported on γ-Al2O3 were compared in the catalytic gasification, and the effects of reaction temperature, system pressure, catalyst loading, space velocity, and rice husk particle size were also studied. The results show that ZnO/γ-Al2O3 obtained at a calcination temperature of 650 °C exhibits the highest activity. The optimal conditions are: 800 °C, 0.1 MPa, ZnO loading of 7.5%, space velocity of 240 h− 1, and rice husk particle size of 0.20–0.30 mm. Under such conditions, 22.1% of CO content, 22.4% of CO2 conversion, and 71.7% of rice husk conversion are obtained.