Targeted waveform enhanced plasma microreactor: Engineering Chemistry at the Interface of Microbubbles

一类电化学反应是在等离子体状态下的反应。在过去的十年里，PI和他的团队一直是等离子体微反应器的先驱，这种反应器直接送入微泡中。随着等离子体反应器的输出直接进入微泡，最大活化度被保留在气泡中，从而促进了微泡界面上活性物质的形成。最近，这种方法已被用于催化游离脂肪酸的酯化反应生成酯(特别是生物柴油)。除了等离子体激活的微气泡反应的有效性外，微气泡的处理也不受电极表面积的限制。这项提议的宏伟目标是通过调节微泡气液界面上的等离子体激活物种来创建多相催化能力。传统的电化学在扩大规模方面存在严重的问题。等离子体微反应器，特别是那些以注入微泡的形式进入液体介质的微反应器，是一种潜在的容易升级的电化学反应器。微泡每立方米的液体反应物体积可以有数公顷的气液界面，因此如果(等离子体)电化学反应能够在气液界面上催化，那么在大体积、连续流动的反应器中就可以实现高通量的反应速率。在厌氧消化的中试工厂研究中，已经实现了0.15公顷/秒的气泡表面积通量！如果这种表面积通量中的一小部分在调节等离子体化学转化方面是有效的，那么转化过程的速度应该远远超过传统的非均相反应。这个项目旨在优化等离子体激活物种的形成与等离子体电子的瞬时操作之间的耦合，等离子体电子产生的激发物种最终在微气泡气液界面上反应。例如，初步研究表明，激发空气等离子体的成分可以随着反应堆中接触时间和施加的电场而发生显著变化。他们还指出，电场在空间和时间上的施加方式极大地影响了等离子体的化学成分，从而影响了微泡介导的气液化学过程中的化学反应。这一建议的目的是描述时变的等离子体电子输出之间的耦合，如通过可调电气工程设计实现的，以及等离子体和微气泡介导的反应的诱导化学。特征将被捕获在允许反转的计算机模型中；根据所需的化学输出，将预测最佳的等离子体电子设计、控制和操作模式(“波形”)。在英国，等离子体化学研究很活跃，但工作主要集中在核科学、二氧化碳耦合等离子体及其在表面处理(即EP/K018388/1)和医疗应用方面的应用。在全球范围内，几个研究小组正在更一般地研究定制的波形等离子体，但没有具体应用于工业规模的化学产生。所提出的定制波形等离子体微泡反应器的闭环控制为提高效率、吞吐量和放大提供了新的可能性。因此，这是对这些研究小组(国内和国际)贡献的补充，因此将刺激新的研究和商业机会。通过将化学工程、电气工程和数学领域的专家聚集在一起，再加上提供GB 160k支持的大约8个项目合作伙伴，可以推动蓝天方法来定向控制等离子体反应的波形(使用新颖的化学建模和波形发生器设计)，同时开辟一条使工业适应改变游戏规则的化学生产方法的道路。

One class of electrochemical reaction are reactions in the plasma state. The PI and his team have been pioneering plasma microreactors that feed directly into microbubbles for the last decade. With the output of the plasma reactor entering the microbubble directly, the maximum activation is retained in the bubble, which then mediates the formation of active species on the microbubble interface. Recently, this approach has been used to catalyse the esterification reaction of free fatty acids to form esters (particularly biodiesel). More than the effectiveness of the plasma activated microbubble reaction, microbubble processing is not limited by surface area of "electrode" in quite the same way. The grand aim of this proposal is to create heterogeneous catalysis capability by tuning the plasma activated species on the gas-liquid interface of microbubbles. Conventional electrochemistry has severe issues around upscaling. Plasma microreactors, particularly those that feed into liquid media as injected microbubbles, are a class of electrochemical reactors that can potentially upscale readily. Microbubbles can have hectares of gas-liquid interface per cubic metre of liquid reactant volume, so if the (plasma)electrochemical reaction can be catalysed on the gas-liquid interface, high throughput reaction rates can be achieved in large volume, continuous flow reactors. Already achieved in pilot plant studies of anaerobic digestion is a bubble surface area flux of 0.15 hectares/sec! If even a fraction of this surface area flux is effective at mediating plasma chemical transformations, the rate of transformation processes should far exceed conventional heterogeneous reactions.This project aims to optimise how the formation of plasma-activated species is coupled to the transient operation of the plasma electronics that create the excited species that eventually react at microbubble gas-liquid interfaces. Preliminary studies show that the composition of an excited air plasma, for instance, can dramatically change with the contacting time in the reactor and the electric field applied. They also suggest that how that electric field is applied in space and time dramatically affects the chemical composition of the plasma, and consequently what chemical reactions dominate the microbubble mediated gas-liquid chemistry. The purpose of this proposal is to characterise this coupling between the time-varying plasma electronics output, as implemented with tuneable electrical engineering design, and the induced chemistry of the plasma and microbubble mediated reaction. The characterisation will be captured in computer models that permit inversion; from the desired chemical outputs, the optimum plasma electronics design, control and operating mode ("the waveform") will be predicted. In the UK plasma chemistry research is vibrant but the work is mainly centred on nuclear science, capactively coupled plasmas with applications to surface treatment (i.e. EP/K018388/1) and medical applications. Globally, several research groups are investigating tailored waveform plasmas more generally but not with specific application to chemical generation on an industrial scale. The proposed closed-loop control of tailored waveform plasma microbubble reactors offers new possibilities to increase efficiency, throughput and scale-up. This, therefore, complements the contributions from these research groups (both national and international) and so will stimulate new research and commercial opportunities. By bringing together experts from the interface of chemical engineering, electrical engineering and mathematics who, together with some eight project partners providing £160k of support, can drive a blue-skies approach to targeted waveform control of plasma reactions (using novel chemical modelling and waveform generator design) while blazing a trail for industrial adaptation to a game-changing approach to chemical production.