Enabling production of sustainable chemicals by understanding microwave reactor engineering hydrodynamics

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Electrification of chemical processes is part of the energy transition that aims at reducing the carbon footprint of various industries in Canada. There is a need for the chemical industry, traditionally a heavy consumer of fossil energy, to adapt its processes and give a more dominant place to the use of electricity. Microwave reactions, using electricity to promote chemical reactions, have shown tremendous potential at the laboratory scale to improve product yield, quality and the energy efficiency of chemical reactors. Over the last 10 years, breakthrough advances have been made towards the deployment of microwave technology at industrial level by the Canadian technology company Pyrowave. They have developed a catalytic microwave depolymerization reactor which can effectively pyrolyze polystyrene to produce styrene monomers which can be used to synthetize virgin-grade polystyrene. Considering that only 30% of Canadian communities have access to polystyrene recycling facilities and that the Pyrowave process can work efficiently with contaminated polystyrene, this cost-effective and high-yield technology would tremendously reduce the amount of plastic waste generated in Canada. Pyrowave currently faces issues in the operation and optimization of their reactor. A number of these issues are related to the impact of the microwaves, which generate local high-temperature sites which are beneficial to the pyrolysis, but which must be controlled to ensure adequate yield and structural integrity of the reactor. This requires in-depth understanding of the multiphase flows within the reactor when it is subject to microwave radiation. The proposed project combines multiphase computational fluid dynamics (CFD-DEM) and experimental work to understand, quantify and predict the influence of microwave radiation on the solid-fluid flow patterns and heat transfer within the reactor. The project will use the microwave-assisted pyrolysis reactor of Pyrowave as model system since this reactor exists at an industrial scale. We believe that the outcomes of this project will enable the design of new catalytic microwave depolymerization reactors which will be a key contributor to the circular economy of tomorrow.