Dehydrogenation of cycloalkanes over Pt/SBA-15 for endothermic cooling

Abstract

Dehydrogenation of cyclohexane, methylcyclohexane, and decalin was studied on Pt/SBA-15 between 773 and 873 K for application to engine cooling in hypersonic aircraft. While the reactions were unstable at 1 bar, the reactions showed no evidence for deactivation at pressures of 20 and 60 bar for at least 4 h. Selectivities for dehydrogenation of cyclohexane to benzene and methylcyclohexane to toluene were greater than 90% in all cases. The reaction of decalin proceeded sequentially, forming primarily tetralin at low reactor space times and naphthalene at higher space times. The reaction of 50% mixtures of n-dodecane and decalin at 773 K showed negligible conversion of n-dodecane but the reaction of decalin was similar to what was observed for a pure decalin feed. Heat measurements gave endothermicities that were in good agreement with standard reaction enthalpies.