Microwave-enhanced catalytic oxidation of VOCs: from lab-scale optimization to pilot-scale industrial application

• Process simulations were performed at conditions near industrial implementation • Microwave-enhanced catalysis significantly lowers VOC oxidation temperatures. • Microwave thermal effect is adversely affected by air flow rate or humidity • Response surface modeling provided optimal parameters for various contaminants. • Promising lab results are validated in pilot reactor using a 7.5 kg Pd/Al 2 O 3 . Microwave-intensified catalytic oxidation is an innovative solution for sustainable efficient removal of volatile organic compounds (VOCs) from dilute air streams. The aim of this experimental study was to comprehensively investigate the microwave enhancements in the context of technology industrial implementation. We applied 5 mm Pd/Al 2 O 3 pellets, a commercial catalyst suitable for industrial use, to decompose various VOCs, with temperature, air flow rate and humidity as process variables. For comparison, the laboratory experiments were conducted using two analogous 50 ml fixed-bed reactors - one with microwaves and one with conventional heating. Our results demonstrated that microwaves could save 10 to 30 % of energy in the catalytic oxidation by decreasing its effective temperature. However, this microwave thermal effect was reduced at high flow rates and humid air. Using linear regression models developed on the principles of response surface methodology, we estimated the optimal parameter ranges for each contaminant. To verify these promising results for upscaling, the process was then tested in a multimode microwave reactor with a 7.5 kg Pd/Al 2 O 3 fixed bed, a 6 kW microwave generator, and the flow rate up to 1.5 m³ min -1 . The VOC conversion data from these pilot tests closely matched our laboratory results and model predictions. Characterized in detail by process parameters, our data provide new insights for the evaluation of industrial application potential and further technology development. Through effective process control, microwave adoption may significantly reduce energy and material demands of industrial applications, such as the treatment of industrial ventilation streams.