Microwave-Assisted Hydrogen Production from Methylcyclohexane Dehydrogenation over Pt-Sn/Al2O3 Catalysts: Investigation on the Effect of Sn Promoter.

Catalytic dehydrogenation of a liquid organic hydrogen carrier like methylcyclohexane is considered as a potential solution for hydrogen transportation storage. Hydrogen production via the catalytic dehydrogenation of methylcyclohexane (MCH) was performed over a Pt-based catalyst in a microwave reactor to determine the effective catalyst systems. It was found that Pt/Al2O3 displayed good MCH conversion and hydrogen production rates but faced urgent issues including C-C bond cleavage side reactions and undesirable coke deposition. After Sn was introduced as a promoter, we explored the optimal ratio of Sn and its promoter effects. Pt0.6Sn0.6/Al2O3 showed comparable dehydrogenation activity and less coke compared with single Pt/Al2O3. According to the characterization analysis of XPS, H2-TPR and NH3-TPD, the Sn promoter induced the formation of the Pt-Sn alloy and masked the medium and strong acidic site of Al2O3. Excessive Sn loading enhanced the formation of Sn rich alloy, which explains the reduced catalytic activity and stability.