ENVIRONMENTALLY SAFE SYNTHESIS OF HYDROGENATION NICKEL CATALYSTS

Abstract

New types of nickel catalysts are proposed. They are formed during the surface deposition of nickel polynuclear hydroxo complexes on powdered carriers with subsequent reduction to the metal. This method of synthesis is environmentally friendly, safe and waste-free technology. Industrial wastewater will contain only an aqueous solution of sodium chloride and sodium carbonate. The catalytic activity was determined by the p-nitroaniline hydrogenation at 240 °C and 40 bar of hydrogen pressure. The properties and characteristics of the catalysts were studied using thermo-programmable desorption of ammonia, Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. It was found that Ni/γ-Al2O3 catalyst may accelerate the process with NiO, NiO, γ-NiOOH and Ni(OH)2 compounds, while for Ni/SiO2 these are NiO, NiO, Ni2O3, γ-NiOOH and Ni(OH)2. However, pre-activation of the sample is necessary. The solution of this problem can be the catalyst activation in a gas atmosphere under hydrogen pressure, but at a lower temperature of about 250 °C. Changes in the metal content in the catalysts before and after use may be associated with the mutual transformations of modifications, which may or may not depend on the catalysis of the hydrogenation process. We established that the catalyst supported on gamma alumina was 10 times more active than the catalyst on silicon oxide. The discovery of the mechanism of transformations between modifications of oxides and metal hydroxides is of considerable interest in the development of new selective and environmentally friendly catalysts.