Process Intensification of Biological Methanation (BM) Systems

该项目旨在探索使用固定化在生物炭框架上的生物酶将二氧化碳（CO2）转化为甲醇（CH3OH）的想法。生物酶是无机催化的强大而可持续的替代品；然而，它们也带来了挑战。酶必须足够健壮，才能在不利的环境中发挥作用，比如二氧化碳排放。由于回收率低，溶液中的游离酶也造成了不可思议的高操作成本。解决这些问题最有效的方法之一是通过固定；不幸的是，许多研究受到复杂的方法和酶活性丧失的限制。生物炭最近作为一种稳定、惰性和经济的酶固定化基质出现，可以克服这些限制。与与基质结合（这会影响活性）相反，酶通过表面官能团固定在生物炭上。这可以创造一种生物催化系统，在不影响功能的情况下提供酶的稳定性；为努力脱碳的行业提供二氧化碳捕获技术，为实施基于捕获的解决方案所需的重大投资带来经济回报。这项研究将从工程生物炭开始，从可持续的英国林业产品中提取生物炭，以确保其物理化学性质有利于酶的最佳附着和活性。然后确定酶结合的最佳条件（pH、时间、温度、酶和离子浓度）。然后，它将在纯二氧化碳和烟气中测试二氧化碳对甲醇的生物催化作用。最后，如果研究的概念验证得以实现，我希望进行生命周期、技术经济和市场途径分析，以确定过程的可持续性，并确定加速技术吸收和采用的途径。仅在2018年，化石燃料生产的甲醇就向大气中排放了2.11亿吨二氧化碳。如果实现了概念验证；这项新技术可以取代甲醇制造中化石燃料的使用，甲醇的需求在2018年达到9800万吨，并且还在增加。这也可能为CCUS在努力消除二氧化碳排放的成长型行业（如水泥和钢铁行业）的投资创造机会，这些行业占全球二氧化碳排放量的9%以上。甲醇在未来也将继续作为燃料电池汽车的氢源和转化为二甲醚（一种用于运输的超清洁柴油燃料）的需求。这种可持续甲醇的提供可以帮助运输脱碳，运输目前占全球二氧化碳排放量的6%。二氧化碳捕获和转化为甲醇的主要方法是通过稀有金属催化，这与费用和可持续性问题有关。这种生物催化方法将通过利用生物炭作为酶附着的反应基质来克服这些障碍。生物炭和酶是可再生的，广泛可用，价格合理，这可能导致更低的碳足迹和更具竞争力的过程。此外，酶介导的转化在较低的温度和压力下表现最佳，使其更节能。这将是同类研究中首次在多酶级联系统中使用生物炭。人们希望该系统概念的证明将激励对酶介导的碳捕获的进一步研究。

This project seeks to explore the idea of using biological enzymes immobilised on a biochar framework to convert carbon dioxide (CO2) to methanol (CH3OH). Biological enzymes present a powerful and sustainable alternative to inorganic catalysis; however, they also present a challenge. Enzymes must be robust enough to work within adverse environments, such as CO2 exhaust outflows. Free enzymes in solution also create unfeasibly high operational costs due to low recovery rates.One of the most effective ways to solve these issues is through immobilization; unfortunately, many studies are limited by complex methodology and loss of enzyme activity. Biochar has recently emerged as a stable, inert, and economical matrix for enzyme immobilisation that could overcome these limitations. As opposed to being bound onto the matrix - which impacts activity - enzymes are instead held in place on the biochar by surface functional groups. This could create a bio-catalytic system that provides enzyme stability without affecting functionality; offering industries struggling to decarbonise a CO2-capture technology that generates an economic return on the significant investment required to implement capture-based solutions.This study will begin by engineering biochar from sustainable UK-based forestry products to ensure its physiochemistry facilitates optimal enzyme attachment and activity. Then, it will determine the optimal conditions (pH, time, temperature, enzyme and ionic concentration) for enzyme binding. It will then test bio-catalysis of CO2 to methanol in pure CO2 and flue gas. Finally, if the study proof-of-concept is achieved, I hope to conduct lifecycle, technoeconomic and pathways-to-market analyses to determine process sustainability and identify pathways to accelerate technology uptake and adoption.In 2018 alone, methanol production from fossil fuels contributed 211 million tonnes of CO2 emissions into the atmosphere. If proof of concept is achieved; this novel technology could replace the use of fossil fuels in methanol manufacturing, demand for which has reached 98 million tonnes in 2018 and is increasing. It could also create an opportunity for CCUS investment in growing industries struggling to eliminate CO2 emissions, such as the cement and steel industry, which contribute over 9% of global CO2 emissions. Methanol will also continue to be in demand in the future as a source of hydrogen for fuel cell vehicles and for conversion to dimethyl ether - a super clean diesel fuel for transport. This provision of sustainable methanol could assist in transport decarbonisation, transport is currently responsible for 6% of global CO2 output.The leading method for CO2 capture and conversion to methanol is via rare-metal catalysis, which is associated with expense and sustainability concerns. This biocatalytic method will overcome these barriers by utilising biochar as the reaction matrix, to which the enzymes are attached. Biochar and enzymes are renewable, widely available, and affordable, which could result in a lower carbon footprint and a more competitive process. Also, the enzyme-mediated conversion performs optimally at lower temperatures and pressures, making it more energy-efficient.This would be the first study of its kind to use biochar in a multi-enzyme cascade system. It is hoped that proof of the system's concept will incentivise further investigations into enzyme-mediated carbon capture.