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，以应对应对气候变化所需的能源生产可持续性的重大社会需求（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（即生物油）的主要技术路线之一，具有高达75wt%的液体产率。然而，在不去除生物油中的大量氧（约38wt%）的情况下，不可能实现生物油作为有效能量载体的潜力。从工艺角度来看，沸石裂解是一种很有前途的常压脱氧技术，不需要大量的氢气。由焦炭形成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主要问题，并且使它们不适于进一步开发。因此，开发新的催化工艺，抑制焦炭的形成，延长沸石催化剂的使用寿命，将是实现经济高效的生物炼油厂的重要举措。本项目的概念是开发一系列新兴技术，以解决生物油升级中的焦化问题。这种组合基于（i）对具有分级特征的碳化硅（SiC）开孔泡沫载体（例如负载在SiC泡沫上的HZSM-5或HY沸石）的微波吸收性质的探索和（ii）具有增强的传热和传质的微波辅助催化的开发。在微波照射下，通过使用SiC的微波吸收材料作为催化剂载体，在载体处选择性地产生热，因此热通量从载体表面经由沸石层被引导到主体流体。由于耦合矢量促进分子从催化剂表面的活性位点脱附，以及防止焦化，传质也将在相同方向上发生。该项目首次提出使用微波吸收结构催化剂和微波活化的组合来解决传统沸石生物油裂化系统中的结焦问题。建议的研究包括建议的催化系统使用模型和真实的生物油的可行性研究，以及与传统的热活化系统相比，系统的能源效率的评估。该提案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基础上，旨在提供一种新型催化系统的概念验证，该系统具有增强的催化剂寿命，低焦炭形成和生物油脱氧的高效率。

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.