Novel supported Rh, Pt, Ir and Ru mesoporous aluminosilicates as catalysts for the hydrogenation of naphthalene

Abstract

Rh, Pt, Ir and Ru have been directly incorporated in mesoporous aluminosilicates prepared using direct liquid crystal templating with a non-ionic surfactant via addition of the corresponding metal complexes to the synthesis gel. In this approach, the non-ionic surfactant plays the role both of porogen and dispersant for the metal ions throughout the aluminosilicate, leading to controlled metal particle formation. Chemical–physical characterisation, simulated coking and regeneration tests, and catalytic behaviour towards naphthalene hydrogenation and ring opening are described. The catalyst activity in the hydrogenation of naphthalene has been studied at atmospheric pressure at 200 and 300 °C, and at 6 MPa between 220 and 340 °C. At atmospheric pressure, all four catalysts give a naphthalene conversion in the range of 95–96% at 200 °C, while at 300 °C, the Rh and Ru catalysts have the highest selectivity to high molecular weight (HMW) hydrogenolysis and/or ring-opening products, as shown by the relatively high formation of alkylbenzenes and decadiene. The effect of parameters such as temperature, contact time and H 2/naphthalene ratio on conversion and selectivity to partially or fully hydrogenated products, HMW products and low molecular weight gases, was investigated under 6 MPa for the supported Rh catalyst. It provides a naphthalene conversion up to 98–99% and interesting selectivity, with a high proportion of HMW products between 260 and 300 °C, and a good thermal stability.