Flexible Routes to Liquid Fuels from CO2 by Advanced Catalysis and Engineering

在提供燃料以满足日益增长的能源需求的同时，迫切需要解决全球二氧化碳排放量和大气二氧化碳水平加速增长的问题。英国政府的目标是到2050年减少80%的排放量（在1990年的水平上），到2020年减少34%的中期目标。越来越清楚的是，储存可变可持续能源（如太阳能或风能）的关键方法是以储存化学能的形式，而这很可能是以氢的形式。然而，尽管氢气本身具有优异的单位重量焓值，但它是一种低密度气体，具有储存困难，并且需要相对较高的压缩能。目前的建议侧重于将可持续生产的氢转化为高能量密度的液体燃料，包括甲醇、二甲醚和碳氢化合物，这些燃料更容易运输，并与现有的燃料分配网络兼容。这些燃料含硫量低，并且可以灵活地取代液态燃料池中的化石燃料，为未来的低碳强度燃料方案做出贡献。它们可以用于运输燃料（在未来一段时间内它们可能仍是重点），作为混合成分，作为季节性储存候选物（利用它们的持久性和能量密度），用于分布式发电或局部供暖。这些液体燃料的合成将以二氧化碳为载体，与太阳能或风能输入的氢发生反应。因此，我们的目标是开发新技术，通过仅利用水作为氢的来源来减少大气中的二氧化碳负担，避免高度吸热的热催化蒸汽重整。原则上，英国发电每年的二氧化碳排放量（约150 × 10^6吨）足以满足英国对液体运输燃料的需求，或者是世界甲醇年产量（约45 × 10^6吨）所需量的三倍。这种二氧化碳有许多可能的有吸引力的集中点来源，包括为封存而制备的二氧化碳或来自氨厂的二氧化碳，如果能够开发出有效的催化技术，这些二氧化碳在中期可用于制造液体燃料。因此，我们将开发新的催化技术，用于生产合成气（CO/H2）和简单的燃料有机物，最终由太阳能驱动，利用从水中可持续产生的二氧化碳和H2。我们将探索将氢气和合成气生产与从废物或生物质等生物源生产合成气相结合，以提供额外的饲料灵活性。我们的部分工作将开发新的和有针对性的催化剂，用于从具有可变CO2， H2和水含量的合成气中热催化生产“绿色”燃料，重点是过程系统工程考虑，特别是在工艺设计中解决低碳方面的问题，例如初级可再生能源的间歇性。行业合作伙伴已经认可了这一方法，并将在点源二氧化碳供应、催化剂制造、液体燃料合成、电解槽制造、可持续制氢和技术集成、生命周期分析和工业燃料使用等方面提供关键投入。该提案采用多学科催化剂发现、部署和过程工程方法来开发、评估和优化利用太阳能（以及间接利用风能或海洋能源）从二氧化碳和水中提取液体燃料的热、光和电催化途径。直接热和太阳能辅助合成甲醇和二甲醚的途径将与逐步太阳能/电化学合成气生成加热二甲醚或费托合成碳氢化合物的途径进行比较。在流程系统建模和分析的基础上，将对支持每条路线的新型催化剂化学成分进行集成，以确定优化方案，这些方案将通过在潜在供应链中扮演关键角色的行业合作伙伴的输入来进行基准测试。

There is an urgent need to address the accelerating increase in global CO2 emissions and atmospheric CO2 levels while providing fuels to meet growing energy needs. The UK government has targeted an 80% reduction in emissions (from 1990 levels) by 2050 with an interim target of 34% reduction by 2020. Increasingly, it is becoming clear that a key approach to storage of variable sustainable energy sources such as solar or wind power is in the form of stored chemical energy, and that this is likely to be as a form of hydrogen. However, although hydrogen itself has excellent enthalpy content per unit weight, it is a low density gas, has storage difficulties, and requires relatively high compression energy. The present proposal is focused on the conversion of sustainably produced hydrogen to high energy density liquid fuels including methanol, DME and hydrocarbons which are more easily transported and are compatible with existing fuel distribution networks. These fuels are low in sulfur and flexible in their contribution to future low carbon-intensity fuel scenarios by displacing fossil sources from the liquid fuels pool. They can be used for transport fuels (where they are likely to remain the focus for some time to come), as blending components, as seasonal storage candidates (exploiting their permanence and energy density), for distributed power production or for local heating.The synthesis of these liquid fuels will be achieved using CO2 as a vector to react with hydrogen from solar or wind inputs. We therefore aim to develop new technology to reduce the atmospheric CO2 burden by utilising only water as a source of this hydrogen, avoiding highly endothermic thermocatalytic steam reforming. The annual CO2 emissions from UK electricity generation (around 150x10^6 tonnes) is sufficient, in principle, to supply the UK requirement for liquid transportation fuels, or three times the amount required for the world annual production of methanol (around 45x10^6 tonnes). There are a number of possible attractive concentrated point sources of this CO2, including CO2 prepared for sequestration or from ammonia plants, which could be used to make liquid fuels in the medium term provided efficient catalytic technologies could be developed. Thus we will develop new catalytic technology for the production of synthesis gas (CO/H2) and simple fuel organics, ultimately driven by solar energy using CO2 and H2 sustainably produced from water. We will explore integration of hydrogen and syngas generation with production of syngas from biogenic sources such as waste or biomass to provide additional feed flexibility. Part of our work will develop novel and targeted catalysts for the thermocatalytic production of 'green' fuels from syngas with variable CO2, H2 and water content, focused by process systems engineering considerations that specifically address low-carbon aspects such as intermittency of primary renewable power in process design. Industry partners have endorsed the approach and will provide key input into the form of point source CO2 supply, catalyst manufacture, liquid fuel synthesis, electrolyser manufacture, sustainable hydrogen generation and technology integration, life cycle analysis and industrial fuel usage.The proposal adopts a multidisciplinary catalyst discovery, deployment and process engineering approach to develop, evaluate and optimise thermal, photo- and electro-catalysed routes to liquid fuels from CO2 and water using solar energy (and, indirectly, wind or marine power). Direct thermal and solar-assisted paths to methanol and DME will be compared with stepwise solar/electrochemical syngas generation plus thermal DME or Fischer-Tropsch hydrocarbon synthesis paths. The novel catalyst chemistries enabling each route will be integrated on the basis of process systems modelling and analysis to identify optimised schemes that will be benchmarked by input from industry partners with key roles in potential supply chains.