日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

Chemical reactions utilizing microwave heating have gained much attention recently, because compared to conventional heating, microwave heating increases reaction rate and reduces the temperature. When solid catalysts have the ability to absorb microwaves, heating only the catalyst, which is an actual reaction area, reduces energy consumption because it becomes unnecessary to heat the reactor and solvent. However, zeolites, which are often used as industrial catalysts, are difficult to heat via microwave radiation. Zeolite catalysts suitable for microwave heating were developed by forming composites of zeolites with carbon, enabling them to absorb the microwave effectively. When the zeolite pores were partially filled with carbon, the internal part of the zeolite particles could be heated by microwaves; moreover, only the zeolite catalyst over which the reaction occurred was heated. Thus, the catalytic reaction primarily occurred within the catalyst itself as it was heated from the inside. Consequently, unselective reactions catalyzed by acid sites on the external surface of the zeolites were inhibited, improving the shape selectivity.