Low temperature hydrogenation of aromatics over Pt-Pd/SiO2-Al2O3 catalyst

Bimetallic Pt-Pd catalysts supported on amorphous silica-alumina (ASA), having different amounts of SiO2 (1.5, 5, 20, 40, and 70%), are prepared by conventional impregnation method. The prepared catalysts are characterized using nitrogen adsorption-desorption isotherms at 77 K and X-ray diffraction (XRD) technique, respectively. Temperature Programmed Desorption (TPD) of ammonia and CO chemisorption experiments are used to study the role of support composition on catalyst acidity and surface active noble metal content, respectively. The effect of noble metal loading and support properties on hydrogenation reaction is investigated via toluene hydrogenation reaction under varying operating conditions (temperature = 383-523 K, pressure = 20 bar, weight hourly space velocity (WHSV) = 1-12 h− 1). Based on the obtained results, Pt (0.18 wt.%)-Pd (0.18 wt.%) loaded ASA catalyst with 40 wt.% silica showed excellent toluene hydrogenation activity. Such trend is further reinforced from naphthalene hydrogenation studies wherein complete conversion with about 90% selectivity for decalin is noticed at 453 K. Accordingly, possible advantage w.r.t. minimal noble metal loading to employ Pt (0.18 wt.%)-Pd (0.18 wt.%)/ASA (40% silica) catalyst for hydrogenation aromatics in transportation fuels, and producing specialty solvents such as DAK (De-aromatized Kerosene) has been envisaged.