Search

This study aims to evaluate the effect of surface acidity of fumed silica nanoparticles in adsorption and subsequent thermal cracking of Colombian asphaltenes. The acidities of the surfaces were established through Temperature Programed Desorption (TPD) experiments. The adsorption equilibrium of asphaltenes was determined using a static batch method, and the data obtained was fitted using the Langmuir model, the Freundlich model and the SLE Model. Asphaltenes catalytic oxidation experiments were conducted, and it was found that this process was surface nature dependent. In all cases, the temperature of asphaltenes oxidation was reduced regarding the virgin asphaltene sample. The effective activation energies were estimated with the iso-conversional OFW method. This energy was found to be related to adsorption affinity and asphaltenes self-association on nanoparticles surface.

An important oil production impact is the increase of environmental pollution due to discharge of water formation. This paper presents a study of oil adsorption onto hydrophobic silica, i.e., silica nanoparticles impregnated with Colombian vacuum residue (VR) at 2 and 4 wt% and onto zeolite and impregnated zeolite nanoparticles (2 and 4wt% of VR) to reduce the amount of O/W emulsion. The Langmuir and Freundlich adsorption models were used to fit the experimental information of the adsorption isotherms. Initial crude oil concentration ranges from 200 to 2000 mg/l. Oil concentration, after adsorption, was determined by using an UV-vis spectrophotometer. The highest oil removal was obtained with impregnated silica nanoparticles, yielding values of 200 mg/g, with 100% oil removal, 9 mg/g more than the value obtained by modified zeolite of 191 mg/g at the same initial concentration. Pseudo-first-order and pseudo-second-order models were used to fit the experimental data of the adsorption kinetics, with better results for the pseudo-second order model.

To determine the problem of fines migration on packed beds and offer a possible solution for this issue, an adsorptive system of packed beds was developed for experimental simulation of fines migration and stabilization by using silica nanoparticles. The adsorbent beds were prepared with Ottawa sand and glass spheres (average radius of 0.53 mm). Three different sand beds were used in the investigation: clean sand (water- wet system), sand submitted to a damage process using an extra-heavy Colombian crude oil (oil-wet system) and sand treated with silica nanoparticles (5-15 nm). Fines suspension was prepared with alumina nanoparticles (50 nm) and distilled water. Results show that beds treated with silica nanoparticles present idealized patterns for the rupture curve, indicating that silica nanoparticles capture and retain fines, decreasing fines migration due to their adsorption capacity.