Rationalizing the catalytic performance of γ-alumina-supported Co(Ni)–Mo(W) HDS catalysts prepared by urea-matrix combustion synthesis

Abstract

A comparative study of the influence of Co (or Ni) promoter loadings and the effect of different sulfurizing agents and sulfurizing temperatures on the structure, morphology and catalytic performance of Mo-or W-based hydrodesulfurization (HDS) catalysts was carried out. Catalyst performance using a tubular fixed-bed reactor and the HDS of thiophene as a model reaction was evaluated. The oxidic and sulfurized states of the HDS catalysts were characterized by laser Raman spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and high resolution transmission electron microscopy (HRTEM). It has been found that the urea-matrix combustion (UMxC) synthesis is a simple tool for preparing supported catalysts in a short period of thermal treatment. Several consecutive stages such as urea melting, metal precursor dissolution and chemical reactions take place before and upon combustion process. The C 4 H 4 S/H 2 -activated Co-(or Ni-) promoted MoS 2 (or WS 2 ) catalysts present a strong synergistic effect (SE) when the Co (or Ni)/Mo (or W) molar ratio is near to 0.5, whereas the C 4 /C 4 = molar ratios display a weak antagonistic effect. Alumina-supported Ni-W catalyst showed an optimal SE 2.5 times higher than those for Co (or Ni)-promoted Mo HDS catalysts. The kinetic parameters for thiophene-HDS reaction were also determined, suggesting that the C-S bond cleavage reaction for alumina-supported Co(Ni)-Mo HDS catalysts and H 2 activation reaction for Ni-promoted WS 2 catalysts play an important role in the rate-limiting step.

WITHDRAWN: Fabrication of Nimo Nanostructured Catalyst via Ultrasonic-Assisted Combustion Method Used in High Efficiency Thiophene Hydrodesulfurization: Influence of Organic Compound Type

“…The second mass reduction is attributed to the total decomposition of Ni and Mo precursor salts as well as decomposition of remained organic additives resulting in evolution of CO 2 , N 2 and H 2 O. [6,33]. The second mass loss which is related to combustion reaction in prepared nanocatalysts with citric acid, urea, glycine and ethylene glycol is 33%, 28%, 34% and 12%, respectively.…”

“…The combustion technique is a fast, simple and energy saving method which is based on the redox reaction between an organic compound (fuel) and oxidizer agent, including sulfates, nitrates and carbonates [31,32]. A wide variety of organic compounds such as urea [33], glycine [34,35], citric acid [36], ethylene glycol [37], starch [38] and a mixture of them [39] have been used through combustion method.…”

High activity Ni/MoS2 catalysts obtained from alkylthiometalate mixtures for the hydrodesulfurization of dibenzothiophene

“…Moreover it is suggested that the pronounced asymmetry results from the partial incorporation of carbon into the MoS 2 structure, at least in the surface, and from increased bending and folding of the MoS 2 layers [34,45]. Recently, Raman studies of promoted catalysts obtained by urea-matrix combustion synthesis on alumina support revealed similar distortions of MoS 2 [46]. In the mid-IR region a broad band centered at around 1100 cm )1 is observed (see figure 5).…”

Ni-Mo Supported Nanoporous Graphene as a Novel Catalyst for HDS and HDN of Heavy Naphtha

“…Therefore, the amount of sulfur and nitrogen compounds in fuels should be decreased to provide a clean environment. Hydrodesulfurization (HDS) (Gao et al, 2011;González-Cortés et al, 2006;Hajjar et al, 2015Hajjar et al, , 2016aHajjar et al, , 2017aHajjar et al, , 2017bHuirache-Acuña et al, 2012;Mendoza-Nieto et al, 2015;Miller et al, 2000;Shan et al, 2015) and hydrodenitrogenation (HDN) (Sundaramurthy et al, 2006;Zepeda et al, 2016) are the main processes considered for reducing the Total Sulfur (T.S.) and Total Nitrogen (T.N.)…”