Multi-stimuli Responsive Smart Hydrogels for Energy-Efficient CO2 capture

碳捕获和封存(CCS)在全球和英国都被广泛认为是全球低碳能源组合的重要组成部分，需要将全球平均气温上升控制在比工业化前水平高2摄氏度以下。CCS是唯一可以在中短期内大幅减少发电和工业过程碳排放的现有技术，碳捕获是整个CCS链中第一个也是最昂贵的单一元素。各种形式的水胺洗涤是目前最好的可用技术，并已在各种规模上进行了演示。然而，尽管近年来在各种规模上的密集发展，其巨大的能源损失，相当于典型电厂发电量的20%，仍然是一个主要的性能障碍。显然，需要探索新的具有成本效益和能源效率的捕获概念，从而大幅减少对能源的惩罚。最近在温度响应性水凝胶领域的研究已经成功地应用于先进的目标分离，这一提议旨在开发一种新的概念，利用光热双响应型智能水凝胶来洗涤二氧化碳，预计这种洗涤将比胺洗涤节能得多。在这一新的捕集概念中，功能性智能水凝胶被用作二氧化碳捕集的吸收剂，这种凝胶在机械化学上对热和阳光辐射都有反应。水凝胶对热和/或光的快速响应与诱导的pH波动相结合，可以在温和得多的条件下促进吸附剂的快速再生/二氧化碳的回收。预计吸附剂再生的温度摆动范围可以从胺洗涤的约70-90℃缩小到20-30℃。更重要的是，基于光热双响应型水凝胶的二氧化碳捕获技术有可能利用低品位的热量和/或阳光或太阳辐射来驱动二氧化碳捕获系统。主要目标包括：(I)开发具有高可逆二氧化碳吸收能力和良好体积相变行为的光热双响应水凝胶；(Ii)表征不同双响应水凝胶在不同温度摆动和光辐射条件下的物理化学性质和二氧化碳吸收/解吸特性，以确定用于捕获二氧化碳的最佳智能水凝胶。(Iii)一旦确定了最佳水凝胶，将利用专门设计的实验室规模的膜和柱在不同的热摆动条件下，在不同的热摆动条件下，利用不同强度的光辐射，进行放大生产，以进行循环二氧化碳洗涤试验。测试结果将用于评估这一新的二氧化碳洗涤概念的可行性，以促进该技术的进一步开发和扩大。

Carbon capture and storage (CCS) has widely been considered, both globally and in the UK, as a crucial part of global low carbon energy portfolio required to control the rise in global mean temperature below 2 degree C above pre-industrial levels. CCS is the only technology available that can achieve deep reductions in carbon emissions from both power generation and industrial processes in the short-to-medium term, with carbon capture representing the first and most costly single element of the whole CCS chain. Aqueous amine scrubbing at its various forms is currently the best available technology and has been demonstrated at various scales. However, despite the intensive developments at various scales over recent years, its large energy penalty, equivalent up to 20% of a typical power plant output, still remains a major performance barrier. Clearly, new cost-effective and energy-efficient capture concepts leading to substantial reductions in energy penalty need to be explored. Prompted by recent research in areas of thermo-responsive hydrogels which has led to successful applications in advanced target separations, this proposal aims to develop a new concept of CO2 scrubbing with photo-thermo dual-responsive smart hydrogels, which is expected to be substantially more energy-efficient than amine scrubbing. In this new capture concept, functionalised smart hydrogels, which are mechno-chemically responsive to both heat and sunlight radiation, are used as the absorbent for CO2 capture. The rapid response of the hydrogels to heat and/or light combined with the induced pH swing can facilitate rapid sorbent regeneration/CO2 recovery under much milder conditions. It is anticipated that the temperature swing range for sorbent regeneration can be narrowed to as low as 20-30 degree C, from ca. 70-90 degree C for amine scrubbing. More importantly, the photo-thermo dual-responsive hydrogels-based CO2 capture could potentially make it possible to make use of low grade heat and/or sunlight or solar radiation to drive the CO2 capture system. The major objectives include:(i) To develop photo-thermal dual responsive hydrogels with high reversible CO2 absorption capacities and favourable volume phase transition behaviours;(ii) To characterise the physicochemical properties and the CO2 absorption/desorption characteristics of different dual-responsive hydrogels under various temperature swing and light radiation conditions to identify the best-performing smart hydrogels for CO2 capture.(iii) Once the optimal hydrogels have been identified, scale-up production of the hydrogels will be carried out to perform cyclic CO2 scrubbing tests with the smart hydrogels, using the purpose-designed lab-scale film and column absorbers under different thermal swing conditions with and without light radiation at variable intensities. The test results will be used to assess the feasibility of this new CO2 scrubbing concept to facilitate further development and scale-up of the technology.