Pt Catalyst Supported on Multi-Walled Carbon Nanotubes for Hydrogenation-Dearomatization of Toluene and Tetralin

A type of MWCNT-supported Pt catalysts for the hydrogenation-dearomatization (HDA) of aromatics was developed, which displays excellent performance for HDA of two model compounds, toluene and tetralin. Over the 1% Pt/CNTs catalyst, near 100% conversion of toluene or tetralin was observed under the reaction temperature of 373 K. The specific reaction rate of HDA of toluene and tetralin reached 0.0524 and 0.0174 mmol s(-1) (m(-surf.)(2) (Pt))(-1), respectively. Both of the values were 1.18 times those (0.0444 and 0.0148 mmol s(-1) (m(-surf. Pt)(2))(-1), respectively) of the 2.4% Pt/AC catalyst with the optimal Pt loading under the same reaction conditions. It was experimentally found that using the CNTs in place of AC as the support of the catalyst did not cause a significant change in the apparent activation energy for the HDA reaction of toluene or tetralin, but led to a certain increase in the molar percentage of catalytically active Pt-species (Pt-0) in the total Pt-amount at the surface of the functioning catalyst. In addition, the Pt/CNTs catalyst could reversibly adsorb a greater amount of hydrogen under atmospheric pressure and temperatures ranging from room temperature to 773 K. This unique feature would help to generate a microenvironment with higher stationary state concentration of active hydrogen-adspecies at the surface of the functioning catalyst. These effects favored increasing the rate of the HDA reaction of toluene or tetralin.