Microwave-assisted upgrading of fast pyrolysis bio-oil using structured zeolites on microwave-absorbing foam supports

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Biomass is a key renewable feedstock to respond to the vital societal need for a step change in the sustainability of energy production required to combat climate change (80% reduction in greenhouse gas emissions by 2050 in the UK). Fast pyrolysis is one of the major technical routes to convert biomass to more valuable energy forms, i.e. bio-oil, with high yields of liquids of up to 75 wt%. However, it is not possible to realise the potential of bio-oil to be an effective energy carrier without removing the large amount of oxygen in bio-oil (about 38 wt%). From a process point of view, zeolites cracking is a promising technology to remove the oxygen from bio-oil at atmospheric pressure without the requirement of large amount of hydrogen. The catalyst deactivation caused by the coke formation remains a major concern for the bio-oil upgrading routes based on zeolite cracking and makes them not viable for further development. Therefore, the development of novel catalytic processes, which could suppress the coke formation and extend the life of zeolite catalysts, would be a major move in making a reality a cost-efficient bio-refinery.The concept of this project is the development of a combination of emerging technologies for addressing the coking issue in bio-oil upgrading. This combination is based on (i) the exploration of the microwave-absorbing property of silicon carbide (SiC) open-cell foam supports with hierarchical characteristics (e.g. HZSM-5 or HY zeolites supported on SiC foams) and (ii) the development of microwave-assisted catalysis with enhanced heat and mass transfers. Under microwave irradiation, by using the microwave absorbing material of SiC as the catalyst support, heat is generated selectively at the support, and hence the heat flux is directed from the support surface to the bulk fluid via the zeolite layer. Mass transfer will also occur in the same direction due to the coupling vector facilitating the desorption of molecules from the active sites of the catalyst surface, as well as preventing the coking. This project, for the first time, proposes to use the combination of microwave-absorbing structured catalysts and microwave activation to address the coking issue in traditional zeolite bio-oil cracking systems. The proposed research consists of the feasibility study of the proposed catalytic system using model and real bio-oil as well as the evaluation of system energy efficiency in comparison with the conventional thermally activated systems. This proposal builds on the investigators' expertise in structured catalysts, microwave chemistry, heterogeneous catalysis, biomass thermo-chemical conversion and process development, aiming at delivering the proof-of-concept of a novel catalytic system with the enhanced catalyst longevity, low coke formation and high efficiency of deoxygenation of bio-oil.