Functionalization of silica nanoparticles with tungsten oxides for catalytic decomposition of asphaltenes
Urresta Aragón, Julián Diel | 2019
In this study, supported tungsten oxide nanoparticles were synthesized, characterized and evaluated for adsorption and catalytic performance on air/steam gasification of Colombian asphaltenes. Silica nanoparticles of 30 nm in diameter were synthesized using a sol-gel methodology and functionalized with tungsten oxides, which were prepared by an incipient wetness technique, using three different solution concentrations (1%, 3%, 5% wt) and calcination temperatures (350 °C, 450 °C, 650 °C). Equilibrium batch adsorption experiments were conducted at 25 ºC with model solutions of asphaltenes in toluene at concentrations ranging from 100 mg·L-1 to 2000 mg·L-1, and catalytic steam gasification of adsorbed heavy fractions was carried out by thermogravimetric analysis. The adsorption isotherms were described by the solid¿liquid equilibrium (SLE) model, and the effective activation energies were estimated with the iso-conversional OFW method. The results showed the enhancing of asphaltenes decomposition by the action of the metal-oxide nanoparticles due to the reduction in the decomposition temperature of the asphaltenes up to 120 °C in comparison with the system in the absence of nanoparticles. Synthesis parameters such as temperature and impregnation dosage play an essential role in the adsorptive and catalytic activity of the materials, possibly due to geometric and electronic effects on the surface and different metal-support interactions.