Surface properties and catalytic conversion of cyclohexane over carbon supported bimetallic catalysts

Carbon supported chromium oxide (AC), chromium oxide-cobalt (ACCo) and chromium oxide-nickel (ACNi) catalysts were prepared by impregnation method. The structural characteristics were examined by FT-IR and X-ray diffraction (XRD) techniques. The magnetic susceptibility of the prereduced samples was determined using the Gouy method. The textural parameters (surface area and porosity) were determined from the low temperature adsorption of nitrogen at 77 K. The base neutralization capacity was investigated with different basic adsorbate, namely NaOH, Na2CO3 and NaHCO3. The catalytic conversion of cyclohexane by all prepared samples was studied in the temperature range 623-723 K, using the microcatalytic pulse technique. The FT-IR revealed that alpha-Cr2O3 is the only detectable phase. Moreover, it shows the presence of some acidic surface groups. The adsorption of NaOH, Na,CO, and NaHCO3 on the investigated samples confirms the presence of carboxylic and phenolic groups as a surface acidic groups. The textural parameters were found to be affected by loading levels of the impregnates. The catalytic hydrogenolysis (HGS) and dehydrogenation (DHG) of cyclohexane were strongly influenced by the presence of alpha-Cr2O3; the metal content and the magnetic susceptibilities of investigated catalysts. (C) 2000 Elsevier Science B.V. All rights reserved.