Enhanced conversion of tetralin dehydrogenation under microwave heating: Effects of temperature variation

Effects of temperature variation in microwave-induced system of tetralin dehydrogenation on the enhancement of reactivity were investigated. The enhancement of heating ability of Pt-supported activated carbon catalyst (Pt/AC) particle and decreasing of an existing temperature gradient (non-uniformed heat distribution) in tetralin solution under microwave heating and boiling-reflux condition were examined by three methodologies: an employment of Dewar-like insulation reactor (DIR), addition of an ionic liquid as an optional microwave absorber in the system, and optimization of the catalyst to the reactant in the reaction system. The Dewar-like insulation reactor was used to prevent heat loss in the heterogeneous solution. Under microwave heating with DIR, the reaction can be heated approximately 3 °C above the normal boiling point of tetralin. In comparison to the reaction carried out in a conventional reactor, tetralin conversion increased from 31% to 56% under 190 W microwave irradiation. Addition of an ionic liquid to the system to function as a heating promoter remarkably enhanced the heating rate of tetralin. However, the ionic liquid deactivated the activity of the catalyst in the reaction. Optimization of tetralin to Pt/AC catalyst in the reaction system improved heat distribution and showed an interesting result. It was found that the reaction performed under the liquid film state showed the highest tetralin conversion, 69% with the microwave irradiation for 60 min.

► Microwave–induced dehydrogenation of tetralin under catalysis of Pt/AC.
► Effect of heat distribution in a microwave-heated heterogeneous reaction.
► Dewar-like insulation reactor is used to preserve heat in microwave heating system.
► Optimization of catalyst/tetralin ratio improves the heat distribution.