Effect of precursor on the catalytic properties of Ni₂P/SiO₂ in methyl palmitate hydrodeoxygenation

Abstract

The effect of phosphorus precursor on the physicochemical and catalytic properties of silica-supported nickel phosphide catalysts in the hydrodeoxygenation (HDO) of aliphatic model compound methyl palmitate (C15H31COOCH3) has been considered.

HDO of Methyl Palmitate over Silica-Supported Ni Phosphides: Insight into Ni/P Effect

“…is the observed reaction rate, R particles is the catalyst particles radius, C s is the reactant surface concentration and D eff is the effective diffusion coefficient. The details of the procedure used for calculation of the Weisz-Prater numbers in case of methyl palmitate HDO was described previously in reference [15]. The Weisz-Prater numbers for hydrogen and methyl palmitate for the most active high-loaded h-Ni1P2 sample in methyl palmitate HDO were found at a temperature of 290 The catalytic properties of silica-supported Ni phosphide catalysts with different initial Ni/P molar ratio and Ni content are summarized in Table 2.…”

“…Two main regions of the spectra of all the measured nickel phosphide catalysts can be highlighted. The first region from +500 to +5000 ppm corresponds to Ni-P intermetallic compounds such as Ni 12 P 5 , Ni 3 P, Ni 2 P, NiP, and Ni 5 P 4 [15,29,39] and the second one from +4 to −40 ppm corresponds to the different phosphate species (denoted in this study overall as PO x groups), i.e., phosphoric acid H n PO 4 (3−n)− (~0 ppm), terminal P 2 O 7 4− (~−7 ppm), and internal (PO 3 − ) n (~−22 ppm) phosphate groups in phosphoric acid oligomers [15,29,32,40,41]. For all of the applied catalysts, we detected the lack of the signals with chemical shifts from −30 to −50 ppm that could be attributed to phosphorus-containing species in the form of silicon phosphate [40].…”

“…On the basis of our previous results [15,16] and the literature data reported for the phosphate-containing type of precursors [13,[34][35][36] the reduction temperature of 600 • C was chosen in this study for catalysts preparation. The physicochemical properties of the Ni x P y /SiO 2 catalysts as well as PO x /SiO 2 reference sample, and SiO 2 support are summarized in Table 1.…”

“…To reach a better insight into the Ni/P effect on the catalytic properties of silica-supported nickel phosphide catalysts in methyl palmitate HDO two sets of Ni x P y /SiO 2 catalysts differing in Ni content and Ni/P ratio were used in the present study [15]. The low-loaded catalysts (about 2.5 wt % of nickel) with nearly the same mean particle size are the appropriate candidates for the comparison of specific activities of the Ni x P y /SiO 2 catalysts with the Ni/P ratios 2:1, 1:1 and 1:2.…”

“…In recent years transition metal phosphide systems have proved to be the promising catalysts in HDO of fatty acid methyl esters [7][8][9][10][11][12][13][14][15][16], fatty acids [17] and vegetable oils [5,18] as well as in co-hydroprocessing of vegetable oils and gas oil mixture [19]. Among a number of transition metal phosphides the silica-supported nickel phosphide catalysts were found to display a higher activity in HDO of aliphatic ether [7], which is converted through the complicated scheme with the participation of acid-catalyzed and metal-catalyzed reactions [7,12,14,15,20,21]. Alkanes with the same number of carbon atoms and water are produced in the HDO pathways including hydrogenation-dehydrogenation and dehydration reactions; while DeCO x pathways produce alkanes with shorter carbon chains and CO x molecules via hydrogenolysis of C-C bonds.…”