Chapter 16: Non-uniform Microwave Heating of Heterogeneous Systems: How to Turn Problems into Opportunities

Turning problematic, non-uniform microwave heating into an opportunity is a promising approach to enhancing energy efficiency and reducing environmental impacts due to the chemical processing of heterogeneous systems. Selective microwave heating of materials provides an adequate temperature for the occurrence of an efficient chemical reaction at desired sites while the surrounding media remain unheated, diminishing heat loss and enhancing the energy efficiency. Moreover, the side reactions at non-desired sites, including reactor walls and the surrounding media, are avoided owing to the lower bulk temperature compared to that of the target material, which likely improves the quality of the product. Applying this approach in various microwave-assisted catalytic and non-catalytic processes, including pyrolysis, cracking, and hydrogen production, confirmed an extraordinary improvement in product quality and reduction in energy consumption. Highlighting these advantages will likely increase the demand for scaling up microwave-assisted processes.