Influence of Cobalt Precursor on Efficient Production of Commercial Fuels over FTS Co/SiC Catalyst

Abstract

β-SiC-supported cobalt catalysts have been prepared from nitrate, acetate, chloride and citrate salts to study the dependence of Fischer-Tropsch synthesis (FTS) on the type of precursor. Com/SiC catalysts were synthetized by vacuum-assisted impregnation while N 2 adsorption/desorption, XRD, TEM, TPR, O 2 pulses and acid/base titrations were used as characterization techniques. FTS catalytic performance was carried out at 220˝C and 250˝C while keeping constant the pressure (20 bar), space velocity (6000 Ncm 3 /g¨h) and syngas composition (H 2 /CO:2). The nature of cobalt precursor was found to influence basic behavior, extent of reduction and metallic particle size. For β-SiC-supported catalysts, the use of cobalt nitrate resulted in big Co crystallites, an enhanced degree of reduction and higher basicity compared to acetate, chloride and citrate-based catalysts. Consequently, cobalt nitrate provided a better activity and selectivity to C 5 + (less than 10% methane was formed), which was centered in kerosene-diesel fraction (α = 0.90).On the contrary, catalyst from cobalt citrate, characterized by the highest viscosity and acidity values, presented a highly dispersed distribution of Co nanoparticles leading to a lower reducibility. Therefore, a lower FTS activity was obtained and chain growth probability was shortened as observed from methane and gasoline-kerosene (α = 0.76) production when using cobalt citrate.

Cobalt catalysts on carbon-based materials for Fischer-Tropsch synthesis: a review

“…The nature of the cobalt precursor was found to influence the basicity of the catalysts, the extent of reduction, the metal particle size and distribution on SiC supports [262]. Consequently, different CO conversion, selectivity to SC5+, and chain growth probability during FTS reaction have been reported for different metal precursors [262].…”

“…Many Co precursors such as Co(NO3)2, Co(CH3COO)2, CoCl2, and Co(OH)2 have been used to prepare Co/C catalysts [262][263][264][265]. Bezemer et al [89] and Radstake et al [101] have prepared Co/CNF catalysts with CoCO3 [89], Co(NO3)2 [89,101] and Co(CH3COO)2 [89,101], but it is difficult to make a comparison of Co particle size because the catalysts were prepared with different Co loadings.…”

Oxidative Coupling of Methane over Mn2O3-Na2WO4/SiC Catalysts

“…Silicon carbide (SiC) has some interesting properties, such as its stability at high temperatures, high thermal conductivity, and chemical inertness, which enables SiC to be used as a support for heterogeneous catalysts [29][30][31][32]. There have been some reports on the application of SiC as a substrate for OCM reactions.…”

Surface Chemistry and Catalysis

“…et al [11] investigated Fisher-Tropsch synthesis (FTS) over Co/SiC catalysts with particular emphasis on the impact of cobalt precursor (nitrate, acetate, chloride, citrate) on FTS activity. Surface titration techniques along with an extended characterization by TPR and TEM were employed to gain insight into the structure-activity correlation.…”

“…It consists of 14 high-quality papers, involving: a comprehensive review article on the surface analysis techniques that can be employed to elucidate the phenomenon of electrochemical promotion in catalysis [3]; two theoretical studies (Density Functional Theory, DFT) on H 2 O dissociation and its implications in catalysis [4,5]; two mechanistic studies by means of temperature-programmed desorption/surface reaction (TPD/TPSR) and/or operando spectroscopy on N 2 O formation over NO x storage-reduction (NSR) catalysts [6] and on methanol reforming over cobalt catalysts [7]; two articles on H 2 production by the steam reforming of ethanol [8] or diesel [9] over transition metal-based catalysts; two articles on the production of commercial fuels by Fisher-Tropsch synthesis [10,11]; two articles on Au-catalyzed CO oxidation [12] and preferential CO oxidation [13]; and three experimental investigations regarding the structure-activity correlation of NO oxidation to NO 2 over Mn-Co binary oxides [14], cyclohexene oxidation on TiZrCo mixed oxides [15] and alkene epoxidation on silica nanoparticles [16].…”