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

碳捕集和封存（CCS）已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控制在比工业化前水平高出2摄氏度以下。CCS是唯一可以在短期至中期内大幅减少发电和工业过程中碳排放的技术，而碳捕获是整个CCS链中第一个也是最昂贵的一个环节。各种形式的含水胺洗涤是目前最好的可用技术，并已在各种规模上得到证明。然而，尽管近年来在各种规模上进行了密集的开发，但其巨大的能量损失（相当于典型发电厂输出的20%）仍然是一个主要的性能障碍。显然，需要探索新的成本效益和能源效率的捕获概念，从而大大减少能源损失。通过最近在热响应水凝胶领域的研究，该领域已成功应用于先进的目标分离，该提案旨在开发一种新的概念，即利用光热双响应智能水凝胶进行CO2洗涤，预计比胺洗涤更节能。在这种新的捕获概念中，功能化的智能水凝胶，对热和阳光辐射都有机械化学反应，被用作CO2捕获的吸收剂。水凝胶对热和/或光的快速响应结合诱导的pH摆动可以促进在温和得多的条件下的快速吸附剂再生/CO2回收。预计吸附剂再生的温度摆动范围可以从约20-30 ℃缩窄至低至20-30 ℃。70-90 ℃用于胺洗涤。更重要的是，基于光-热双响应水凝胶的CO2捕集可以潜在地使得可以利用低品位热和/或阳光或太阳辐射来驱动CO2捕集系统。主要目标包括：（i）开发具有高可逆CO2吸收容量和良好体积相变行为的光热双重响应水凝胶;（ii）考察不同双重响应水凝胶在不同变温和光辐射条件下的物理化学性质和CO2吸收/解吸特性，以确定性能最佳的CO2捕获智能水凝胶。(iii)一旦确定了最佳的水凝胶，将进行水凝胶的放大生产，以使用智能水凝胶进行循环CO2洗涤测试，使用专门设计的实验室规模的膜和柱吸收器，在不同的变温条件下，在不同强度下有和没有光辐射。测试结果将用于评估这种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规模。

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.