Catalytic transformation of crude bio-oil to valuable chemicals and fuels

Abstract

Hydrogen has been regarded as the most environmental friendly energy carrier due to its easily-storage and high energy concentration. A variety of technologies have been studied to generate hydrogen. Ethanol steam reforming is one of the most promising ways to generate hydrogen since its high productivity. However, the high operating temperature is the main challenge for developing the process. Metallic catalysts have been widely investigated to improve the performance of ethanol steam reforming process. Ni-based catalysts are frequently studied due to their good catalytic performance and low cost for ESR. However, quick deactivation is still a major challenge for Ni-based catalysts, which is mainly caused by coke formation or metal sintering. In this thesis, improvements of Ni-based catalysts have been studied in two approaches: introducing a second metal of Cu to form bimetallic catalysts and Optimizing Ni content in catalysts that Ni is supported on CaO modified Al2O3. Bimetallic CuNi/YSZ catalysts were synthesized by impregnation. Results showed that adding Cu to Ni-based catalysts successfully improved the catalytic stability while Cu has barely activity in ESR. The formation of Cu-Ni alloy can improve catalyst reducibility and stabilize Ni from sintering. Ni supported on CaO modified Al2O3 catalysts were synthesized by co-precipitation. Introducing of CaO to Al2O3 support successfully improved the stability of catalysts by reducing acidity sites since the acidic property of Al2O3 leads to serious coke formation in ESR. Different Ni loading ratios contribute to the formation of different Ni-containing compounds, which have various catalytic performances in ESR. Increasing Ni loading ratio has positive effect on catalytic activity. But excess Ni loading does influence the particle size, metal dispersion and reducibility.