Palladium-Containing Catalysts Based on Functionalized CNFs for the Dehydrogenation of Methylcyclohexane

Abstract

The activity of palladium-containing catalysts based on functionalized carbon nanofibers prepared by an incipient wetness impregnation method in the dehydrogenation reaction of methylcyclohexane was investigated. Methylcyclohexane is considered as one of the most promising liquid hydrogen carriers. The dependence of the catalytic characteristics of the samples on the functionalization conditions of carbon nanofibers has been studied. By temperature-programmed desorption, it was shown that an increase in the treatment time of carbon nanofibers in concentrated nitric acid from 1 to 3 h increases the number of hydroxyl groups on their surface, and treatment for 6 h contributes to a rise in the concentration of carboxyl groups and their derivatives (esters and anhydrides). Additional calcination of the functionalized nanofibers in an inert atmosphere at 530°C yielded a sample containing predominantly hydroxyl groups. The presence of hydroxyl groups on the surface of the carbon material has a positive effect on the performance of the catalysts, while the presence of carboxyl groups leads to a decrease in the yield of toluene. It is assumed that the observed differences in catalyst activity are due to differences in dispersion and localization of palladium particles.