Hydroisomerization of n-heptane over MoP/Hβ catalyst doped with metal additive

The bifunctional catalysts of molybdenum phosphide supported on H beta zeolite (MOP/H beta) were prepared using a co-impregnation-temperature-programmed reduction method, and catalytically tested in the hydroisomerization of n-heptane. The catalytic conversion and isomerization selectivity of MoP/H beta were revealed to be higher than those of the control tungsten phosphide sample WP/H beta and the HMCM22-supported counterpart MOP/HMCM22. Moreover, doping Cr, Ni, or Ce significantly improved the activity of MoP/H beta; meanwhile, the Cr-promoted catalyst also gave an enhanced selectivity to isomerization products. The catalysts were characterized by X-ray diffraction, Brunauer-Emmett-Teller analysis, temperature-programmed desorption of NH3, and temperature-programmed reduction of H-2. Accordingly, it is suggested that the promoting effect of the secondary metal additive is relative to the reduction of MOPOx species, as well as the pores and add sites of the beta zeolite. (C) 2014 Elsevier B.V. All rights reserved.