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.

The CDT in Molecules to Product addresses an overarching concern articulated by industry operating in the area of complex chemical products. It centres on the lack of a pipeline of doctoral graduates who understand the cross-scale issues that need to be addressed within the chemicals continuum. Translating their concern into a vision, the focus of the CDT is to train a new generation of research leaders with the skills and expertise to navigate the journey from a selected molecule or molecular system through to the final product that delivers the desired structure and required performance. To address this vision, three inter-related Themes form the foundation of the CDT - Product Functionalisation and Performance, Product Characterisation, and Process Modelling between Scales. More specifically, industry has identified a real need to recruit PGR graduates with the interdisciplinary skills covered by the CDT research and training programme. As future leaders they will be instrumental in delivering enhanced process and product understanding, and hence the manufacture of a desired end effect such as taste, dissolution or stability. For example, if industry is better informed regarding the effect of the manufacturing process on existing products, can the process be made more efficient and cost effective through identifying what changes can be made to the current process? Alternatively, if there is an enhanced understanding of the effect of raw materials, could stages in the process be removed, i.e. are some stages simply historical and not needed. For radically new products that have been developed, is it possible through characterisation techniques to understand (i) the role/effect of each component/raw material on the final product; and (ii) how the product structure is impacted by the process conditions both chemical and mechanical? Finally, can predictive models be developed to realise effective scale up? Such a focus will assist industry to mitigate against wasted development time and costs allowing them to focus on products and processes where the risk of failure is reduced. Although the ethos of the CDT embraces a wide range of sectors, it will focus primarily on companies within speciality chemicals, home and personal care, fast moving consumer goods, food and beverage, and pharma/biopharma sectors. The focus of the CDT is not singular to technical challenges: a core element will be to incorporate the concept of 'Education for Innovation' as described in The Royal Academy of Engineering Report, 'Educating engineers to drive the innovation economy'. This will be facilitated through the inclusion of innovation and enterprise as key strands within the research training programme. Through the combination of technical, entrepreneurial and business skills, the PGR students will have a unique set of skills that will set them apart from their peers and ultimately become the next generation of leaders in industry/academia. The training and research agendas are dependent on strong engagement with multi-national companies, SMEs, start-ups and stakeholders. Core input includes the offering, and supervision of research projects; hosting of students on site for a minimum period of 3 months; the provision of mentoring to students; engagement with the training through the shaping and delivery of modules and the provision of in-house courses. Additional to this will be, where relevant, access to materials and products that form the basis of projects, the provision of software, access to on-site equipment and the loan of equipment. In summary, the vision underpinning the CDT is too big and complex to be tackled through individual PhD projects - it is only through bringing academia and industry together from across multiple disciplines that a solution will be achievable. The CDT structure is the only route to addressing the overarching vision in a structured manner to realise delivery of the new approach to product development.