Hydroisomerization of n-octane over bimetallic Ni-Cu/SAPO-11 catalysts

Abstract

Bimetallic Ni-Cu/SAPO-11 catalysts were prepared by co-impregnation method and assessed in the hydroisomerization of n-octane. Their physicochemical properties were characterized by means of powder X-ray diffraction, nitrogen adsorption-desorption, temperature-programmed desorption of ammonia, pyridine-adsorbed infrared spectroscopy, temperature-programmed reduction of hydrogen, transmission electron microscopy, energy dispersive X-ray, and X-ray photoelectron spectroscopy. The Ni-Cu alloy was formed after reduction in the H2 flow at 450°C. Copper changed the electronic interaction of nickel and diluted the nickel ensemble size in the Ni-Cu alloy. The hydrogenolysis reaction that decreases the selectivity of isomerization was effectively restrained over the bimetallic Ni-Cu/SAPO-11 catalysts. The selectivity to n-octane isomers over the bimetallic nickel (3%) and copper (1.5%) catalyst was 19% more than that over the monometallic nickel (3%) catalyst at the conversion of 70%. A possible reaction scheme was proposed to explain the catalytic properties in n-octane hydroisomerization.