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

一类电化学反应是等离子体状态下的反应。在过去的十年里，PI和他的团队一直在开拓直接进入微泡的等离子体微反应器。等离子体反应器的输出直接进入微泡，在微泡中保留最大的活性，从而介导微泡界面上活性物质的形成。近年来，该方法已被用于催化游离脂肪酸酯化反应生成酯（特别是生物柴油）。与等离子体激活微泡反应的有效性相比，微泡处理不受“电极”表面积的限制。该方案的宏伟目标是通过调节微气泡气液界面上的等离子体活化物质来创造多相催化能力。传统的电化学在升级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，是一类可能很容易升级的电化学反应器。微气泡每立方米的液体反应物体积可以有数千公顷的气液界面，因此，如果（等离子体）电化学反应可以在气液界面上催化，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！即使这个表面积通量的一小部分有效地介导等离子体化学转化，转化过程的速率应该远远超过传统的非均相反应。该项目旨在优化等离子体活化物质的形成如何与等离子体电子的瞬态操作耦合，等离子体电子产生最终在微泡气液界面反应的激发态物质。例如，初步研究表明，受激空气等离子体的成分会随着反应器中的接触时间和施加的电场而发生巨大变化。他们还提出，电场在空间和时间上的作用方式会极大地影响等离子体的化学成分，从而影响微泡介导的气液化学中主导的化学反应。本提案的目的是表征时变等离子体电子输出之间的耦合，如可调谐电气工程设计所实现的，以及等离子体和微泡介导反应的诱导化学。特征将被捕获在允许反演的计算机模型中；从期望的化学输出，最佳的等离子电子设计，控制和操作模式（“波形”）将被预测。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、电容耦合等离子体与表面处理的应用（即EP/K018388/1）和医疗应用。在全球范围内，几个研究小组正在更广泛地研究定制波形等离子体，但没有具体应用于工业规模的化学生产。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，吞吐量和规模提供了新的可能性。因此，这补充了这些研究小组（国内和国际）的贡献，从而将刺激新的研究和商业机会。通过汇集来自化学工程、电气工程和数学领域的专家，以及大约8个提供16万英镑支持的项目合作伙伴，可以推动等离子体反应目标波形控制的蓝天方法（使用新颖的化学建模和波形发生器设计），同时为工业适应改变游戏规则的化学生产方法开辟道路。

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.