Ni₂P/SBA-15 As a Hydrodeoxygenation Catalyst with Enhanced Selectivity for the Conversion of Methyl Oleate Into n-Octadecane

Abstract

A novel hydrodeoxygenation catalytic system, Ni2P/SBA-15, has been synthesized by temperature-programmed reduction of a nickel phosphate precursor impregnated in the mesostructured silica support. The formation of this active phase was verified by X-ray diffraction, whereas the study by transmission electron microscopy revealed that the catalyst is mainly constituted of nickel phosphide particles of relatively uniform size dispersed within the SBA-15 channels. Both Ni2P/SBA-15 and a reference Ni/SBA-15 catalyst were tested for the hydrodeoxygenation of methyl oleate (C17H33–COO–CH3) in a fixed-bed continuous flow reactor. This compound was used as a convenient surrogate of triglyceride molecules present in vegetable oils that following catalytic hydrotreating yields n-alkanes as the main products. In the whole range of pressure studied (3–40 bar) and for temperatures higher than 290 °C, both systems achieve more than 80% ester conversion at 20 h–1 WHSV, although the Ni/SBA-15 catalyst presents a slightly higher activity. Overall, higher pressure and lower temperature and space velocity favors the formation of C18 hydrocarbon, which is the preferred product in terms of carbon atom economy. Nevertheless, under all the assayed conditions, the n-C18/n-C17 ratio was remarkably higher for Ni2P/SBA-15 than for Ni/SBA-15 catalysts. On the basis of these results, it can be concluded that both deoxygenation and decarboxylation occur simultaneously over the Ni2P catalyst, whereas decarboxylation and cracking are the prevailing processes over the Ni catalyst. Owing to these high yields of long-chain paraffins, Ni2P/SBA-15 can be considered as a very promising catalyst for the production of green diesel.

Bifunctional Adsorbent-Catalytic Nanoparticles for the Refining of Renewable Feedstocks

“…Consistent with the results of Serrano et al on methyl esters of FFAs, our Ni-MSN catalyst favored cracking (72%) over decarbonylation (25%) and hydrodeoxygenation (3%) (Figure 2). 21 Adsorptive Properties of Aminopropyl Modified Ni-MSN. The current technologies for separation and purification of organic acids involve extraction and distillation using organic solvents and supercritical fluids, which makes the process expensive and energy intensive.…”

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

“…It was mentioned that the catalytic activity of Ni/SBA-15 catalyst is slightly higher than demonstrated by any of the similar prepared Ni 2 P/SBA-15 samples in methyl oleate HDO [8,9]. Guan et al [10] and Xue et al [11] showed the opposite results on methyl palmitate HDO in the presence of Ni/SiO 2 and Ni 2 P/SiO 2 catalysts.…”

“…HDO of triglycerides, fatty esters and acids produce an oxygen-free mixture of alkanes which are the valuable components compatible with petroleum-based motor fuels [6]. 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].…”

Synergetic Effect of Ni2P/SiO2 and γ-Al2O3 Physical Mixture in Hydrodeoxygenation of Methyl Palmitate

“…To avoid the disadvantages of supported noble metals and sulphide catalysts, several new types of systems containing supported base metals, preferentially Ni [13,[34][35][36][37][38][39], or base metal carbides [40][41][42], nitrides [43], and phosphides [44][45][46][47][48][49][50][51][52][53][54] were investigated in HDO. In particular, the nickel phosphide catalysts exhibit the high activity and stability in the HDO of model compounds [44,46,48,50,[55][56][57][58][59][60][61][62][63][64][65][66] and vegetable oils [51,67], as well as in co-hydrotreatment of renewable oils with petroleum-derived distillates [68].…”