[PdCl2{NH2(CH2)(12)CH3}(2)] supported on an active carbon: effect of the carbon properties on the catalytic activity of cyclohexene hydrogenation

The catalytic activity and poisoning resistance of [PdCl2(NH2(CH2)(12)CH3)( 2)], supported on active carbons, have been studied, regarding the effect o f 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 differe nt treatments to purify them or to modify the support surface chemistry. Ac tive carbons were characterised by nitrogen adsorption at 77 K, carbon diox ide adsorption at 273 K, mercury porosimetry, elemental analysis and TPD, C atalysts were prepared supporting the metal complex by the incipient impreg nation method, with a palladium content of ca. 0.3% wt. All the catalysts w ere analysed by XPS and nitrogen adsorption at 77 K. The catalytic activity and sulphur-poisoning resistance were determined in the cyclohexene hydrog enation to cyclohexane. Tetrahydrothiophene (THT) was used as the poisoning agent in a concentration of 300 ppm. Regarding the effect of support poros ity, the catalytic activity increases with supermicropore (diameter from 0. 7 to 2 nm) volume. With regard to the oxygen surface groups and sulphur con tent 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 t han that observed for the unsupported metal complex and the complex support ed on gamma-Al2O3. (C) 2000 Elsevier Science B.V. All rights reserved.