Joint UK / China Hydrogen production network

考虑到全球变暖带来的日益严重的威胁，以及确保两国能源供应的需要，中英两国提出了在化石燃料清洁能源生产技术方面开展专家合作的建议。该提案的首要主题是通过一系列热化学途径将二氧化碳分离并准备封存，从煤中生产清洁能源/氢气。我们将研究两种形式的先进化学循环，它们允许从化石燃料中生产清洁的氢，而不需要（与当前技术不同）与捕获二氧化碳相关的大量能源损失。这些过程处于发展的早期阶段，需要对概念的基础科学进行研究，以及如何从实验室扩大这些过程。这两种类型的化学循环都利用固体反应物作为二氧化碳受体或氧载体。1. 使用煅烧-碳化循环的高级气化工艺：最初的ZECA工艺旨在从煤中产生氢气，首先将煤加氢气化为甲烷，然后转化为合成气，然后再转化为氢气。转换反应是用氧化钙去除二氧化碳，将水气转换反应的平衡转移到H2。首先需要将甲烷转化为合成气，但煤中的硫会以H2S的形式污染甲烷，并使转化催化剂失活。这里我们将研究转化炉和移位反应器的结合，以及H2S对钙环剂的影响，钙环剂必须在CaO和CaCO3之间反复循环。需要探索一系列燃料的加氢气化，因为这一过程的效率将取决于将固体燃料完全转化为甲烷的能力。在中试规模上，将在循环流化床中研究增强型水气转换工艺的连续运行。利用基于铁氧化物的氧化还原循环制氢：在化学循环燃烧中，燃料可以与金属氧化物（而不是空气）一起燃烧，产生纯二氧化碳流。对于发电，还原的氧化物可以与空气再氧化以释放热量。一些金属和氧化物（如铁）可以与蒸汽部分氧化，产生非常纯的H2。利用合成气可将Fe2O3氧化物还原为FeO或Fe；然后，铁和FeO可以被蒸汽氧化，产生Fe3O4和氢。这个循环可以通过用空气氧化Fe3O4来完成。在这里，我们将研究该过程在实验室规模和中试规模上的连续操作，使用流化和移动床反应器的组合。合成气必须从煤中产生，并且含有焦油和H2S。我们将研究挥发性物质和硫对铁基载体的影响，即金属氧化物燃烧挥发性物质的程度，以及氧化物是否被硫钝化。在气化过程中，还将研究这些金属氧化物和焦油裂解催化剂的使用。钙基CO2受体和金属氧化物基氧载体都必须经过多次循环操作。天然材料往往会迅速降解。可以生产出性能更好的人工颗粒。然而，颗粒的行为是物理结构和添加剂/污染物存在的很强的函数。我们将研究这些材料的配方如何影响它们的物理结构，以及这将对许多周期的反应性产生的影响。

The increasing threat posed by enhanced global warming, together with the requirement to secure energy supplies for both countries have led to this proposal for a collaboration of experts between China and the U.K. in clean technologies for energy production from fossil fuels. The overarching theme of the proposal is the production of clean energy/H2 from coal, via a number of thermochemical routes with the CO2 separated and ready for sequestration. We will investigate two forms of advanced chemical cycles which allow clean hydrogen to be produced from fossil fuels, without (unlike with current technology) a large energy penalty associated with capturing the CO2. These processes are at an early stage of development with research required on the underlying science of the concepts, as well as how these processes can be scaled up from the laboratory. Both types of chemical cycle make use of solid reactants which either act as CO2 acceptors or oxygen carriers. 1. Advanced gasification processes using the calcination-carbonation cycle: The original ZECA process aimed to generate hydrogen from coal, by first hydrogasifying the coal to methane, then reforming to syngas, before shifting to H2. The shift reaction was to be performed using calcium oxide to remove the CO2 and move the equilibrium of the water-gas shift reaction over to H2. The need to first reform the methane in to syngas faced potential problems with the sulphur in the coal which will contaminate the methane as H2S, and deactivate reforming catalysts. Here we will investigate combining the reformer and shift reactors, and the effect of H2S on the calcium looping agent, which must be repeatedly cycled between CaO and CaCO3. The hydrogasification of a spectrum of fuels needs to be explored, since the efficiency of this process will depend on the ability to completely convert the solid fuel into methane. At a pilot scale the continuous operation of enhanced water-gas shift process will be investigated, in a circulating fluidised bed.2. Hydrogen production using the iron-oxide based redox cycle: In chemical looping combustion, a fuel can be burned with a metal oxide (rather than air) to produce a stream of pure CO2. For power generation, the reduced oxide can be reoxidised with air to release heat. Some metals and oxides (e.g. iron) can be partially oxidised with steam to produce very pure H2. Fe2O3 oxide can be reduced to FeO or Fe using syngas; Fe and FeO can then be oxidised with steam giving Fe3O4 and hydrogen. The cycle can be completed by oxidising the Fe3O4 with air. Here we will investigate the continuous operation of this process on a laboratory scale, and on a pilot scale, using a combination of fluidised and moving bed reactors. The syngas must be generated from coal and will contain tars and H2S. We will investigate the affect of volatile material and sulphur on the iron based carrier, i.e. the extent to which the metal oxides can combust the volatiles, and whether the oxides are deactivated by sulphur. The use of these metal oxides ad tar cracking catalysts during gasification will also be investigated. Both the calcium based CO2 acceptors and the metal oxide based oxygen carriers must undergo many cycles of operation. Natural materials will often rapidly degrade. Artificial particles can be produced which have better characteristics. However, the behaviour of the particles is a very strong function of the physical structure, and the presence of additives/contaminants. We will investigate how the formulation of these materials affects their physical structures and the impact this will have on the reactivity over many cycles.