ИСТИНА

Despite the rapidly changing oil prices, interest in renewable resources persists. Triglycerides of fatty acids are one of the promising types of such feedstock. The deoxygenation of such products yield paraffins of fuel composition or higher olefins, which are important products serving as a feedstock for the preparation of detergents, synthetic oils, additives, etc. Metals such as Pd, Pt, Ni or metal sulfides, generally on supports (γ-Al2O3), are used as catalysts [1]. Recently, it has been shown that nickel sulfide Ni3S2 powder can selective catalyzed decarbonylation of fatty acid to higher olefins. These catalysts as distinct from known Ni and Ni sulfide containing ones appeared to have relatively low side activities. The aim of this work was to study the effect of the active component content in the catalyst on the catalyst efficiency in decarbonylation of stearic acid to high olefins [2]. We studied nickel sulfide catalysts supported on alumina or silica by hydrogen reduction of Ni sulfate as the precursor. The amount of loaded metal ranged from 1.5% to 9%, the reduction temperature was 400°C under a hydrogen pressure of 10 atm for 3 h. The experiments were carried out in an autoclave at a hydrogen pressure of 15 atm and a temperature of 350°C. The results of the research showed, that in the presence of the of the alumina- and silica gel-supported catalysts, the olefin selectivity exhibits a tendency to increasing from 30 to 55% with an increase in the nickel content in the catalyst from 1.5 to 9% respectively. For the two supports the increase in the conversion is not monotonous: initially, upon switching from the 1.5%Ni catalyst to the samples containing 3-6 wt % Ni, the conversion quite rapidly increases; afterwards, the increase ceases. The catalysts were studied by TEM combined with Xray microdiffraction, the results of the analysis showed the presence Ni, NiO, NiS and Ni3S2 phases on catalysts. In addition to the phase composition, the particle size of the active component can be responsible for the activity of the catalysts; the average particle size for the alumina and silica gel supports, is 3.1 ± 1.0 and 5.2 ± 1.2 nm, respectively. References [1] Berenblyum A.S., Danyushevsky V.Ya., Kuznetsov P.S. // Pet. Chem. 2016, V. 56. P. 663. [2] Katsman E.A., Danyushevsky V.Ya. // Pet. Chem. 2019, V. 59. P. 622.