Hydrogenation of 2-methylnaphthalene over bi-functional Ni catalysts

Nickel catalysts were synthesized by incipient wetness impregnation and coprecipitation and compared to a commercial Ni/kieselguhr catalyst for selective hydrogenation of 2-methylnaphthalene to yield methyldecalin. The catalysts were characterized using N2 physisorption, TGA, XRD, and TEM. The apparent activation energy for hydrogenation depends on the support identity, with the highest value (87 kJ/mol) obtained for Ni/SiO2-Al2O3 and the lowest (30 kJ/mol) for Ni/kieselguhr. The selectivity to cis-/trans-methyldecalin varied as a function of both catalyst identity and reaction conditions, with high selectivity to cis-methyldecalin obtained using catalysts with higher Ni loadings and at lower reaction temperatures. The impregnation of a precious metal onto coprecipitated Ni catalysts also changed their selectivity, as catalysts containing ruthenium selectively formed cis-methyldecalin, whereas platinum catalysts produced mostly trans-methyldecalin. This research demonstrates that Ni catalysts can be useful for producing inexpensive catalysts for hydrogenation of polyaromatic-containing feedstocks.