PdCl 2(NH 2(CH 2) 12CH 3) 2] supported on an active carbon: effect of the carbon properties on the catalytic activity of cyclohexene hydrogenation

Abstract

The catalytic activity and poisoning resistance of [PdCl 2(NH 2(CH 2) 12CH 3) 2], supported on active carbons, have been studied, regarding the effect of some of the support properties, such as: porosity, surface chemistry and sulphur content. Commercial active carbons and almond-shell-derived carbons were used. Some of the commercial active carbons were submitted to different treatments to purify them or to modify the support surface chemistry. Active carbons were characterised by nitrogen adsorption at 77 K, carbon dioxide adsorption at 273 K, mercury porosimetry, elemental analysis and TPD. Catalysts were prepared supporting the metal complex by the incipient impregnation method, with a palladium content of ca. 0.3% wt. All the catalysts were analysed by XPS and nitrogen adsorption at 77 K. The catalytic activity and sulphur-poisoning resistance were determined in the cyclohexene hydrogenation to cyclohexane. Tetrahydrothiophene (THT) was used as the poisoning agent in a concentration of 300 ppm. Regarding the effect of support porosity, the catalytic activity increases with supermicropore (∅ from 0.7 to 2 nm) volume. With regard to the oxygen surface groups and sulphur content of the active carbons, no effect has been found. Catalyst poisoning by THT is found to be independent of the active carbon properties and lower than that observed for the unsupported metal complex and the complex supported on γ-Al 2O 3.