Effect of Pt particle size on methylcyclohexane dehydrogenation over Pt/Al2O3 catalysts

Abstract

A rational design of highly active and durable Pt catalysts for methylcyclohexane (MCH) dehydrogenation is essential for the utilization of liquid organic hydrogen carriers. Herein, a series of Pt/Al2O3 catalysts supported with a particle size of Pt ranging from 0.78 to 2.02 nm were synthesized and the effect of the particle size of Pt on the activity and stability of the catalyst for the MCH dehydrogenation were studied. The Pt loaded on Al2O3 with an actual average particle size of about 1.57 nm (Pt/Al2O3-1.57) has the highest activity and stability when compared to other Pt/Al2O3 catalysts. The hydrogen evolution rate of Pt/Al2O3-1.57 reaches about 656.12 mmol·gPt-1·min−1 while its apparent activation energy (38.05 KJ·mol−1) and deactivation rate (0.11 %/min) are the lowest. Both the poisoning experiment and the catalyst characterization demonstrate that the competition between the number of active sites and the strength of toluene adsorption explain why the particle size of Pt affects the MCH dehydrogenation. Additionally, the Pt/Al2O3-1.57 catalyst also maintains an excellent performance after three cycles of regeneration.