The paper demonstrates the solvent composition influence on the activity of sulfide catalysts in the methyl palmitate hydroconversion and on selectivity of C₁₆/C₁₅ hydrocarbons formation.

The effect of support nature, SiO₂ and γ-Al₂O₃, on physicochemical and catalytic properties of nickel phosphide catalysts in methyl palmitate hydrodeoxygenation (HDO) has been considered. Firstly, alumina-supported nickel phosphide catalysts prepared by temperature-programmed reduction method starting from different precursors (phosphate–Ni(NO₃)₂ and (NH₄)₂HPO₄ or phosphite–Ni(OH)₂ and H₃PO₃) were compared using elemental analysis, N₂ physisorption, H₂-TPR, XRD, TEM, NH₃-TPD, ²⁷Al and ³¹P MAS NMR techniques and catalytic experiments. The mixture of nickel phosphide phases was produced from phosphate precursor on alumina while using of phosphite precursor provides Ni₂P formation with the higher activity in methyl palmitate HDO. Besides, the comparative study of the performances of Ni₂P/SiO₂ and Ni₂P/Al₂O₃ catalysts demonstrates the apparent superiority of alumina-supported Ni₂P in the methyl palmitate hydrodeoxygenation. Considering the tentative scheme of methyl palmitate transformation, we proposed that cooperation of Ni₂P and acid sites on the surface of alumina provides the enhanced activity of alumina-supported Ni₂P through the acceleration of acid-catalysed hydrolysis.

Two sets of silica-supported nickel phosphide catalysts with a nickel content of about 2.5 and 10 wt % and Ni/P molar ratio 2/1, 1/1 and 1/2 in each set, were prepared by way of a temperature-programmed reduction method using (Ni(CH₃COO)₂) and ((NH₄)₂HPO₄) as a precursor. The Ni_xP_y/SiO₂ catalysts were characterized using chemical analysis N₂ physisorption, XRD, TEM, ³¹P MAS NMR. Methyl palmitate hydrodeoxygenation (HDO) was performed in a trickle-bed reactor at 3 MPa and 290 °C with LHSV ranging from 0.3 to 16 h⁻¹. The Ni/P ratio was found to affect the nickel phosphide phase composition, PO_x groups content and catalytic properties in methyl palmitate HDO with the TOF increased along with a decline of Ni/P ratio and a growth of PO_x groups’ content. Taking into account the possible routes of methyl palmitate conversion (metal-catalyzed hydrogenolysis or acid-catalyzed hydrolysis), we proposed that the enhancement of acid PO_x groups’ content with the Ni/P ratio decrease provides an enhancement of the rate of methyl palmitate conversion through the acceleration of acid-catalyzed hydrolysis.