Photo-catalytic Microbubble reactor for conversion of CO2 to Fuels

许多研究已经清楚地确定了地球大气中的二氧化碳浓度与全球变暖之间的相关性。为了减轻大气中二氧化碳浓度过高的影响，英国政府承诺到2050年将温室气体排放量减少80%。根据能源和气候变化部(DECC)的能源统计报告，2010年，可再生能源对英国总消费量的贡献从6.6%上升到7.4%。然而，为了达到2020年前削减15%的目标，需要大幅提高投资和规划审批流程的速度。据报道，规划许可和投资是实现可再生能源目标的主要障碍。在这种情况下，捕获和转化二氧化碳的瞬时解决方案将提供通向无碳未来的替代途径。在《低碳愿景2050》报告中，预计到2020年，具有碳捕获和封存功能的发电厂将成为清洁电力领域的一项主要技术。在太阳光和半导体催化剂的存在下，二氧化碳和水的同时分解被认为是在短期内获得低碳能源的有吸引力的策略。然而，这种转化过程存在产率低和加工成本高的问题。提高效率的方法之一是使用新型或改性的催化剂。研究人员最近提出了基于膜、纳米二氧化钛管和流态床的二氧化碳转化解决方案。然而，这些方法需要二氧化碳的有效分散和防止多孔催化剂纳米颗粒或纳米管堵塞的机理。在另一种方法中，利用溶解在液体中的二氧化碳来克服堵塞问题。但是，这种方法的缺点是二氧化碳在水中的溶解度很低。因此，这项工作的关键考虑是解决三个问题，即。(I)CO2在水中的溶解度低，(Ii)TiO2光活性低，(Iii)界面电子转移效率低。本项目将使用我们的新型微泡装置在二氧化钛水悬浮液中制备二氧化碳核心微泡泡沫。气泡直径在几十微米范围内促进了CO2的溶解。随后，泡沫将被注入到连续流动的微流控光反应器中，太阳光将垂直于泡沫流动的方向聚焦。该装置的主要优点是可以在两个连续气泡的界面处产生表面等离子体激元。界面厚度在几百纳米范围内起到了波导的作用，产生的表面等离子体将被吸附在气泡界面上的二氧化钛颗粒所吸收。表面等离子体增强了二氧化钛颗粒的光活性，从而增强了其提高反应产物产率的能力。这是首次使用泡沫来产生表面等离子激元。这将避免昂贵的催化剂表面改性步骤。

Many research studies have clearly established correlation between carbon dioxide concentration in earth's atmosphere and global warming. To mitigate the effect of large concentration of atmospheric carbon dioxide, UK government has committed the 80% reduction in greenhouse gas emission by 2050. According to Energy Statistics by the Department of Energy and Climate Change (DECC) report, the contribution of renewable to gross UK consumption has increased from 6.6 to 7.4 per cent in 2010. However, in order to reach the target of the 15% reduction by 2020, massive increase in speed of investment and planning permission approval process will be required. According to report, planning permission and investment are the main hurdles in achieving the renewable energy targets. In such scenario, the transient solution of capturing and converting carbon dioxide would provide alternative route to carbon free future. In low carbon vision 2050 report, it is envisaged that the power plant with carbon capture and storage would be a major technology in clean power segment by 2020. The simultaneous reduction of carbon dioxide with water splitting in presence of sun light and semiconductor catalyst is considered to be attractive strategy in securing low carbon energy in short term. However, this conversion process suffers from the low yield and high processing cost. One way to improve the efficiency is to use novel or modified catalyst. The membrane, nano-TiO2 tubes, and fluidised bed based solutions for CO2 conversion have recently been proposed by the researcher. However, these methods require efficient dispersion of carbon dioxide and mechanism to prevent clogging of porous catalyst nano-particles or nano-tubes. In alternative method, CO2 dissolved in liquid phase is employed to overcome the problem of clogging. But, this method suffers from the low CO2 dissolution in water. Hence, key consideration for this work is to address three problems viz. (i) low dissolution of CO2 in water, (ii) low photoacitivity of TiO2 and (iii) inefficient transfer of electron at interface. This project will employ our novel microbubbling device to prepare the carbon dioxide core microbubbles foam in TiO2 aqueous suspension. The diameter of bubble in few tens of micrometer range promotes the dissolution of CO2. Subsequently foam will be injected into the continuous flow microfluidics photo-reactor where sun light beam will be focused orthogonally to the direction of foam flow. Main advantage of the device is that it can generate the surface plasmon at the interface of two consecutive bubbles. The interface thickness in range of few hundreds nanometre acts as a waveguide and generates the surface plasmon which will be absorbed by the TiO2 particle adsorbed at the bubble interface. Surface plasmon increases the photoactivity of the TiO2 particle and thus, enhances its ability to increase the product yield of the reaction. It is first time foam will be used to generate the surface plasmon. This will allow avoiding costly catalyst surface modification steps.