Pt catalyst supported on multiwalled carbon nanotubes for hydrogenation-dearomatization of toluene

Using home-made multiwalled carbon nanotubes (CNTs) as the support, the Pt/CNTs catalyst was prepared by an incipient wetness method. Performance of the catalyst for hydrogenation-dearomatization (HDA) of toluene was evaluated and compared with the reference catalysts supported on gamma-Al2O3 and activated carbon (AC). Over the 1.0 % Pt/CNTs catalyst under the reaction conditions of 0.4 MPa, 373 K, PhCH3/H-2 = 6/94 (mol/mol) and GHSV = 120 L/(h center dot g), the observed conversion of toluene HDA reached 100 %, and the corresponding specific reaction rate was 0.052 3 mmol/(s center dot m(2)). This value was 1.17 and 1.18 times that of the 1.4 % Pt/gamma-Al2O3 and 2.4 % Pt/AC catalysts with the respective optimal Pt loading, respectively. It was experimentally found that using CNTs in place of gamma-Al2O3 or AC as the support of the catalyst did not cause a significant change in the apparent activation energy for the toluene HDA reaction but led to a slight increase in concentration of catalytically active Pt species (Pt-0) at the surface of the functioning catalyst. In addition, the Pt/CNTs catalyst could reversibly adsorb a greater amount of hydrogen under atmospheric pressure at temperatures from room temperature to 573 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 the toluene HDA reaction.