Microwave-assisted catalytic reactions are considered energy-efficient and have attracted attention in various chemical processes. This is due to the selective and rapid heating of target materials or species, which is especially beneficial for highly endothermic reactions such as Dry Reforming of Methane (DRM)—a promising reaction for utilising methane and carbon dioxide. At present, reaction mechanisms and kinetic advantages under microwave irradiation remain limited. In this study, we applied Steady-State Isotopic Transient Kinetic Analysis (SSITKA) to elucidate the advantages of microwave heating. We successfully revealed that the microwave activation induces the formation of reactive coke, enhancing the rate of DRM. This work was published in the journal Industrial Chemistry & Materials on Jun 12.
Microwave heating is one of the most promising methods to reduce energy consumption, due to the selective and rapid heating of targeted material or chemical species. Many studies have reported enhanced catalytic activity and reduced energy consumption under microwave heating. However, few detailed studies have investigated the effect of microwave heating. This gap is attributed to the uniqueness of microwave heating; unlike conventional heating, microwave heating involves complex factors such as catalyst shape and quantity, which can significantly change temperature distribution and heating properties. Additionally, the setup of microwave reactors makes it challenging to apply analysis in the same way as conventional heating.
To overcome these challenges, Steady-State Isotopic Transient Kinetic Analysis (SSITKA) was applied to investigate the effects of microwave heating. SSITKA is an in-situ technique to gain information about intrinsic kinetics by analysing surface species and their residence time in relation to the product(s) observed. A major advantage of SSITKA is that it allows the observation of transient response while maintaining the steady-state reaction by selectively perturbing the intermediates and product concentrations using isotopic labelling.
In this study, we applied SSITKA for microwave-assisted Dry Reforming of Methane (DRM), which produces synthesis gas (syngas) through the reaction of methane and carbon dioxide—two greenhouse gases commonly found in natural gas and biogas. DRM offers the production of syngas with a ratio that favours the long-chain hydrocarbons and other value-added products. However, due to the thermodynamic stability of both reactants, DRM is highly endothermic and requires high temperatures, making it particularly suited for microwave-assisted reactions.
To analyse the effects of microwave heating on DRM, we switched the reactants between 12CH4 + 12CO2 and 12CH4 + 13CO2, while monitoring the signals of CO and CO2. Under microwave heating, the kinetic response of CO was accelerated compared to conventional heating. This effect became more pronounced at higher methane concentrations. Additionally, the concentration of surface intermediates was notably reduced under microwave heating.
Looking ahead, we hope this work will support a more comprehensive understanding of catalytic reaction processes under microwave heating and contribute to energy-efficient industrial applications using microwave heating.
The research team includes Tatsuya Hamashima, Hajime Hojo, and Hisahiro Einaga from Kyushu University; and Manoj Coppens, José Palomo, and Atsushi Urakawa from Delft University of Technology.
This research is funded by the Japanese Science and Technology Agency (JST) PRESTO, and the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement.
Industrial Chemistry & Materials is a peer-reviewed interdisciplinary academic journal published by Royal Society of Chemistry (RSC) with APCs currently waived. ICM publishes significant innovative research and major technological breakthroughs in all aspects of industrial chemistry and materials, especially the important innovation of the low-carbon chemical industry, energy, and functional materials. Check out the latest ICM news on the blog .
