Microwave science in sustainability

Peter Edwards’ early interest centred on the physical form and electronic properties of colloidal gold for which, in 1857, Michael Faraday presciently, concluded “…consists of that substance in a metallic divided state” and “...a mere variation in the size of its particles gave rise to a variety of resultant colours”. That led him naturally to the concept of the Size-Induced Metal-to-Insulator Transition (SIMIT) .

Herbert Fröhlich and later Ryogo Kubo predicted that the electrical conductivity within a single mesoscale particle is expected to decrease rapidly when its physical dimensions approach the characteristic de-Broglie wavelength scale of the enclosed conduction electrons. Early experiments showed that the microwave conductivity within individual gold particles of diameters ca. 4nm was a factor of 10 to the power of 7 below that of bulk, macroscopic gold. Other studies gave similar observations on the size-dependant conductivities of ultrafine indium and iron particles. With Adrian Porch and Daniel Slocombe, Professor Edward's highlighted, in 2013 the importance of the SIMIT in the microwave absorption and associated heating of mesoscale metal catalyst particles.

Subsequent studies from the Oxford and Cardiff Groups led to the microwave-initiated catalytic Hydrogen-stripping of fossil hydrocarbons – firstly wax, then methane, heavy crude oil, through to diesel and with Michael Jie and colleagues to the catalytic deconstruction of plastics-waste to hydrogen and high-value carbon nanomaterials.

Professor Peter Edwards FRS, University of Oxford, UK

Professor Peter Edwards FRS, University of Oxford, UK

BSc and PhD, Salford University (Dr Ron Catterall, 1975) followed by Fulbright Scholarship at Cornell with Professor Michell (Mike) J Sienko on materials undergoing a Metal-Insulator Transition. Edwards returned to the ICL Laboratory, Oxford, to work with Professor John B Goodenough ForMemRS on the Superconductor-Insulator Transition in oxides. Appointed in 1978 as Demonstrator, then Lecturer in Inorganic Chemistry at Cambridge University. In 1990, Edwards took the Chair in Inorganic Chemistry at the University of Birmingham to join Professor Ian W. Smith FRS and Sir Fraser Stoddart FRS to rejuvenate the subject there. In 2004, he became Statutory Chair, and Head of Inorganic Chemistry at Oxford. With Drs Tiancun Xiao and Benzhen Yao, in the Summer of 2020, Edwards set up OXCCU, a leading company converting carbon dioxide and hydrogen into Sustainable Aviation Fuel (SAF).  Led by CEO Andrew Symes, in May 2023 OXCCU completed a US$23million Series A financing to commercialise cost-effective SAF.

Microwave chemistry started in the late 1980s, and the number of research reports has increased since 2000. The microwaves afford a novel promising technology to achieve process escalation owing to rapid, volumetric, and selective heating by microwaves as opposed to conventional heating. These unique abilities of microwave heating have been summarized as Green Chemistry processes. Moreover, the possibility of scale-up of some reactions has also been examined and a scaled-up reactor design has also been reported. Such developments deepened the understanding of microwave irradiation equipment for chemists and made them imagine their own ideas. Along with this, a connection is being made from microwave chemistry to 'microwave science'. In this trend of the times, we are making connections to hydrogen energy, recycling, food science and bioactivity based on microwave chemistry, and we will introduce this point.

Professor Satoshi Horikoshi, Sophia University, Japan

Professor Satoshi Horikoshi, Sophia University, Japan

Satoshi Horikoshi received his PhD degree in 1999, and was subsequently a postdoctoral researcher at the Frontier Research Center for the Global Environment Science (Ministry of Education, Culture, Sports, Science and Technology) until 2006. He joined Sophia University as Assistant Professor in 2006, and then moved to Tokyo University of Science as Associate Professor in 2008, after which he returned to Sophia University as Associate Professor in 2011. Currently he is President of the Japan Society of Electromagnetic Wave Energy Applications (JEMEA), and is on the Editorial Advisory Board of the Journal of Microwave Power and Electromagnetic Energy and other international 3 journals. His research interests involve new functional material or nanomaterial synthesis, catalytic reaction, food science, biology, formation of sustainable energy, environmental protection using microwave- and/or photo-energy. He has co-authored over 220 scientific publications and has contributed to and edited or co-edited 39 books.

Achieving the decarbonisation of chemical production will require transformative solutions that move the industry away from its reliance on fossil-based feedstocks and energy sources and instead incorporate renewable materials and energy alternatives.  Integrating renewable resources into chemical conversion poses inherent challenges, as they are often distributed rather that concentrated at large-scale centralised facilities. This dynamic creates the potential to co-locate more modular, transportable production systems near these more sustainable resources; a shift that could significantly disrupt the established business model. Researchers at the National Energy Technology Lab (NETL) have identified microwaves as flexible conversion technology platform for electrification and process intensification and are studying microwave-enhanced processes across several research programs. 

One NETL program explores using microwave technology to convert waste associated natural gas, otherwise destined for flaring, into valuable aromatic chemicals. This reaction serves as an example of the challenging nature of catalysis under a microwave field, ie the traditional thermal catalyst (Mo/HZSM-5), is not well matched to coupling with microwaves, and the properties of the catalyst change during reaction (through carbon) that affect the heating and stability of the catalyst.  Through a multi-disciplinary approach NETL is combining experimental and modelling approaches to navigate and understand the complex interactions of microwaves with catalytic materials to improve performance. Through their work NETL researchers have demonstrated the ability to control carbon formation, reduce deactivation rates and demonstrate aromatics can be selectively produced more efficiently using microwaves versus a thermal process. Additionally, NETL is developing specialised in-situ characterisation facilities to study how microwaves impact surface, enabling the design of more active and selective microwave catalysts. 

Dr Daniel Haynes, National Energy and Technology Lab, USA

Dr Daniel Haynes, National Energy and Technology Lab, USA

Dr Haynes has a PhD in Chemical Engineering who works as a researcher on the Reaction Engineering team at the National Energy Technology Lab (NETL). He leverages his expertise in heterogeneous catalysis and microwave chemistry to support decarbonisation of chemical production. In his current role, Dr Haynes leads four projects at NETL focused on advancing microwave-enhanced catalytic processes to produce valuable chemicals more sustainably using waste feedstocks like flare gas and CO2. Additionally, Dr Haynes serves as the portfolio lead for NETL’s Natural Gas Decarbonisation and Hydrogen Technologies Program. This program consists of 10 projects that leverage the natural gas resources and infrastructure to support the development of the hydrogen value chain. Dr Haynes represents NETLs Center for Microwave Chemistry, which serves as a collaboration point between academia and industry for fundamental research and applied application of microwave technology for scale-up and process integration. 

Microwave technology can play a major role in the move to net zero carbon and a circular economy. Recent advances at the University of Nottingham have led understanding in how microwaves can enhance mass transfer in heterogeneous materials such as biomass, soil and plastics. This can be exploited to develop sustainable technologies to process these challenging solid feedstocks: replacing conventional fossil-based heat with renewable electrically powered heat, reducing energy requirements, improving product yields and reducing plant footprints. Current work to develop plastics recycling processes and to utilise agricultural co-products and wastes (eg the 'second harvest') for the development of novel products will be presented.

Professor Eleanor Binner, University of Nottingham, UK

Professor Eleanor Binner, University of Nottingham, UK

Eleanor is a chartered chemical engineer and scientist with 17 years’ experience in the management and delivery of heterogeneous material processing projects in both industry and academia.  She graduated from Imperial College, London, with an MEng in Chemical Engineering 1999. After completing her PhD in microwave plasma processing at Swinburne University of Technology in Melbourne, she spent time working as a contaminated land consultant for Coffey Environments and a postdoctoral research fellow at Monash University in Melbourne.  In 2011, she returned to the UK to pursue an academic career at the University of Nottingham.

Eleanor specialises in microwave technologies for the circular economy, converting wastes to novel products for the food, pharmaceutical and chemical industries.  She has made major contributions to the fundamental understanding of the role of microwave heating during processing and how this can be applied to scale up.  Current projects include plastics recycling and novel lignin extraction.

Energy efficiency, sustainability and economic viability have become priorities in the materials manufacturing sector. Conventional synthesis of solid-state materials is time- and energy-intensive, often requiring high temperatures and complex procedures. Microwave (MW) processing is a viable alternative that addresses these challenges while providing the opportunity to access new and metastable materials and to understand the interaction of solids with electromagnetic fields.

Originally Professor Gregory's MW work focused on carbides – traditionally familiar as structural ceramics, these materials are also finding utility as catalysts. Carbon-containing materials are attractive candidates for MW synthesis on account of the high dielectric loss tangent exhibited by the element at MW frequencies, resulting in rapid temperature increases during MW heating. Reaction times can be orders of magnitude shorter than seen conventionally.

MW synthesis is not restricted to carbides only, however, and his recent work has demonstrated how chalcogenides and nanostructured alloys can be fabricated under relatively low power MW conditions. Chalcogenides such as SnSe and Cu2Se are high figure-of-merit thermoelectrics, capable of converting waste or solar heat into green electricity efficiently. Alloys can be prepared via metal plasmas – Metal Induced Microwave Plasma (MIMP) synthesis. The nano-alloys (eg Laves phases, M2X; M=metal, X=main group metalloid) can be used as sustainable energy materials themselves (again, for example, as thermoelectrics) or as precursors for dealloying to form nanoporous metallic/semiconducting high surface area-high capacity electrodes in metal ion batteries, for example. The porous structure of these materials is crucial in extending the lifetime of high energy density batteries.

Professor Duncan Gregory, University of Glasgow, UK

Professor Duncan Gregory, University of Glasgow, UK

Professor Gregory is the WestCHEM chair of Inorganic Materials, University of Glasgow. He was previously an EPSRC Advanced Fellow, Lecturer then Reader in Materials Chemistry at the University of Nottingham. He is currently a Visiting Professor at Kyushu University and was Vice President of the RSC Materials Chemistry Division Council (2009-2014). His research interests focus on the discovery of new solids including sustainable energy materials (eg Li batteries, fuel storage, thermoelectrics), inorganic nanomaterials and the solid state chemistry of non-oxides. His research also embraces the sustainable production of materials including the microwave synthesis and processing of solids. He has supervised 42 postgraduate students to graduation to-date and has published over 200 papers.

A global transition to net zero will require innovations in materials manufacture that increase efficiency and reduce consumption, all while continuing to meet demand and satisfy application needs. Sustainable manufacturing processes that address the challenges of resource efficiency and multi-level optimisation could reduce manufacturing resource to just the amount required. Here, Professor Cussen will present some of our recent work on the development of microwave chemistry approaches to materials for energy storage as well as our future plans to move from batch synthesis to continuous processes. For example, our observations for garnet electrolyte batch microwave-synthesis (leading candidate materials for safer next-generation solid-state batteries) have demonstrated that these processing techniques can reduce reaction times and temperatures; the rapid, homogeneous microwave heating affords a single-phase high ionic conducting material. We can also target faceted cathode particles, such as high nickel content cathodes for next-generation Li-ion batteries, as well as lower cost cathodes such as olivine materials. The addition of microwave heating can afford materials with less defects, which impacts subsequent battery performance. Professor Cussen will also showcase some of our recent development of in situ muon spin relaxation measurements that allow us to interrogate ion diffusion across electrode-electrolyte interfaces. This talk will highlight how careful synthetic design can enable performance and a comprehensive analysis provides greater insight into materials properties.

Professor Serena Cussen, University College Dublin, Ireland

Professor Serena Cussen, University College Dublin, Ireland

Serena Cussen (née Corr) is Full Professor of Materials Chemistry at University College Dublin. She obtained her BA and PhD degrees in Chemistry from Trinity College Dublin, before going on to carry out postdoctoral research at University of California Santa Barbara with Professor Ram Seshadri. 

Serena's research focuses on understanding the synthesis-structure-function interplay in materials for electrochemical energy storage. Recipient of the RSC Journal of Materials Chemistry Lectureship (2017), the ISIS Science Impact Award (2021) and the RSC Interdisciplinary Prize (2023), Serena is deeply committed to career sustainability, early career mentoring, the promotion of women in STEM and public outreach. A former member of the RSC’s Materials Division Council, she has contributed to the RSC’s Equity in Publishing group (contributing to the recent 'Is publishing in the chemical sciences gender biased?' report) and was featured in the International Women’s Day report 'The Chemical Ladies'.

Facing the global climate crisis, the imperative for sustainable industrial technologies has never been greater. This presentation introduces microwave (MW) technology as a transformative solution for minimising the carbon footprint across global industries. SAIREM explores how MW technology offers a path toward greener industrial processes thought through its fully electrified origin, alongside rapid and selective heating capabilities. 

The presentation provides an overview of industrial MW tools, with a primary focus on efficient gas emissions management and the production of carbon-neutral fuels. The part of the gas management provides case-studies on the decomposition of toxic volatile organic compounds at rates exceeding 99%, representing a critical pillar of sustainability efforts. Additionally, this presentation covers MW methods for the production of hydrogen (H2) from methane (CH4), water (H2O), and biomass at high levels of energy efficiency.

Throughout, Dr Doroshenko will discuss the advantages and limitations of MW technologies, offering a balanced perspective on their role in advancing industrial sustainability.

Dr Alisa Doroshenko, SAIREM, France

Dr Alisa Doroshenko, SAIREM, France

Dr Doroshenko has earned her PhD in 2020 at the University of York. During her PhD, she was making a comparison between MW and conventional processes for biomass-associated reactions. After the PhD, she was working in Kline Group (USA) as a marketing specialist for chemical industries, having joint projects with Solvay, Clariant, Croda, BASF and many others. Since the end of 2021, Dr Doroshenko has joined SAIREM as a Business Development Manager for Labs and R&D. SAIREM is an OEM of MW and RF solutions for industries and labs since 1978. Her area of expertise was also expanded towards MW/RF methods on manufacturing of hydrogen in 2024.