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

生物质是一种关键的可再生原料，以满足应对气候变化所需的能源生产可持续性方面的重大社会需求(到2050年，英国温室气体排放量减少80%)。快速热解是将生物质转化为更有价值的能源形式的主要技术途径之一，即生物油，液体产率高达75wt%。然而，如果不去除生物油中的大量氧气(约38wt%)，就不可能实现生物油作为有效能源载体的潜力。从工艺角度看，沸石裂解是一种在常压下脱除生物油中氧气而不需要大量氢气的很有前途的技术。结焦引起的催化剂失活仍然是基于沸石裂化的生物油改质路线的一个主要问题，使其不能进一步发展。因此，开发能够抑制结焦并延长沸石催化剂寿命的新型催化工艺，将是实现低成本生物精炼的重大举措。该项目的概念是开发一种新兴技术的组合，以解决生物油升级中的结焦问题。这一组合是基于(I)探索具有分级特征的碳化硅(SiC)开孔泡沫载体(例如，碳化硅泡沫载体上的HZSM-5或HY沸石)的微波吸收性能和(Ii)具有强化传热和传质的微波辅助催化的发展。在微波辐射下，利用碳化硅的微波吸收材料作为催化剂载体，在载体上选择性地产生热量，从而将热流通过沸石层从载体表面引导到本体流体中。由于偶联载体促进了分子从催化剂表面的活性中心脱附，从而防止了结焦，因此也将发生相同方向的传质。本项目首次提出将微波吸附结构催化剂与微波活化相结合来解决传统沸石生物油裂解系统中的结焦问题。建议的研究包括使用模型和实际生物油对所提出的催化系统进行可行性研究，以及与传统的热激活系统进行比较来评估系统的能效。这项建议建立在研究人员在结构化催化剂、微波化学、多相催化、生物质热化学转化和工艺开发方面的专业知识的基础上，旨在提供一种新型催化体系的概念验证，该体系具有提高催化剂寿命、降低结焦和生物油脱氧效率的特点。

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.