ИСТИНА

The scientific and technologic efforts in the beginning of XXI century aimed to develop and study the methods of industrial obtaining hydrocarbon fuels basing on the renewable sources (RNS) of natural inedible fats and oils as well as wastes of their edible ones. It resulted in starting of four synthetic kerosene and diesel production plants with 1.5 million tons sum capacity. They utilize technology based on hydrodeoxygenation (HDO) of triglycerides and free fatty acids. The main progress is that this “green fuel” contains no oxygen unlike biodiesel and biokerosene. Selective production of higher olefins (HOs) is an actual problem too, because they are large-tonnage important key reagents of industrial organic syntheses. HOs form partly during HDO and are the primary products of fatty acids decarbonylation (DCO). They completely pass into paraffins in fuel production. Hence, the problem is to search for proper catalyst providing high reaction selectivity to HOs. Stearic (St) and oleic (Ol) acids are prevailing components of above mentioned RNS, and therefore used as the relevant model substances. Literature search showed metal sulfides, and especially Ni, to be promising catalysts for this purpose. They usually form by sulfidation of Ni oxide and keep in this form by continuous injection of sulfiding substance into feed flow. We prepared Ni sulfide catalysts supported on alumina or silica by hydrogen reduction of Ni sulfate as the precursor. These catalysts as distinct from known Ni and Ni sulfide containing ones appeared to have relatively low side activities. The hydrogenation type reactions in their presence are minor. Ol practically does not form St. Moreover Ol does not inhibit the conversion, and the figures for St, Ol and their mixtures are close to those for pure St. C17 diolefins (DCO primary products of Ol) pass to C17 olefins partly. C18 hydrocarbons (HDO products) do not form. Methane (product of CO methanation) is absent. The selectivity to heptadecane is under 10%. The shift reaction is practically absent. Ester and ketone products observed only in traces. In this case, the heptadecenes’ oligomerization is the main side reaction. Overcoming its consequences becomes an actual problem. It partly lightens by the ability of metal catalysts to inhibit the oligomerization of olefins [2]. With the catalyst 3.2% by Ni on silica at 98% St conversion level, we obtained heptadecenes yield of 40%. This figure may sharply rise by using the well-known technological trick – simultaneous heptadecenes removing from reaction zone. References 1. M. Ruinart de Brimont, C. Dupont, A. Daudin, C. Geantet, P. Raybaud // Journal of Catalysis. 2012. V. 286. P. 153. 2. Bullock R.M. // Comm. on Inorg. Chemistry: A J. of Critical Discussion of the Current Literature. 1991. V. 12. № 1. P. 1. The RFBR financially supported this study, projects 15-03-02906 and 14-03-00105.