Dehydrogenation of methylcyclohexane over Pt supported on Mg–Al mixed oxides catalyst: The effect of promoter Ir

Abstract

To enhance the hydrogen release during hydrogen storage, several Pt–Ir supported on Mg–Al mixed oxide catalysts were prepared and then applied into the dehydrogenation of methylcyclohexane (MCH) in this study. The effects of iridium content, reduction temperature on the activity and stability of the catalysts were studied in detail. In the presence of Ir, metal particle size was decreased and electron transfer between Ir and Pt was observed. High reduction temperature increased the metallic Ir content but enlarged the particle size of active sites. During the dehydrogenation reaction on Pt–Ir bimetallic catalyst, MCH was efficiently converted into toluene and PtIr-5/Mg–Al-275 exhibited the highest activity. After prolonging the residence time and raising the reaction temperature to 350 °C, the conversion and hydrogen evolution rate were increased to 99.9% and 578.7 mmol·(g Pt) −1 ·min −1 , respectively. Moreover, no carbon deposition was observed in the spent catalyst, presenting a high anti-coking ability and good potential for industrial application. Hydrogen evolution rate reached up to 578.7 mmol·g Pt −1 ·min −1 in the dehydrogenation of methylcyclohexane on Pt–Ir supported on Mg–Al mixed oxide catalyst and no carbon deposition on the catalyst surface was observed after dehydrogenation reaction.