Kinetic and thermodynamic equilibrium of asphaltenes sorption onto nanoparticles of nickel oxide supported on nanoparticulated alumina

Nanoparticles can be used as adsorbents and catalyst in oil industry for in situ upgrading in the oil industry. The main objective of this study was to investigate the kinetic and thermodynamic equilibrium of asphaltene sorption onto nanoparticles of nickel oxide supported on nanoparticulated alumina at different temperatures, times, and concentrations. Alumina-supported nanoparticles were characterized by N2 adsorption at −196 °C and X-ray diffraction. Complete asphaltene sorption on nanoparticles of nickel oxide supported on nanoparticulated alumina can be effectively reached at relatively short times (around 2 min), making this sorbent a good candidate for asphaltene sorption. The sorption equilibrium of asphaltene for alumina and alumina-supported nanoparticles at different temperatures (25, 40, 55, and 70 °C) over a wide range of asphaltene concentration, from 150 to 2000 mg/L, was determined using a static method. The Langmuir and Freundlich models were used for correlating the experimental data of the sorption equilibrium at different temperatures. Regarding to the Al and AlNi5 samples, the experimental data on asphaltene sorption isotherms were adequately adjusted by the Freundlich model. On the other hand, for the AlNi15 sample the experimental data were adequately fitted by the Langmuir model. The adsorption of asphaltene on NiO supported on alumina was much higher than that over alumina for the range of equilibrium concentrations tested. Pseudo-first-order and pseudo-second-order kinetic models were applied to the experimental data obtained at different concentrations of asphaltenes from 250 to 2000 mg/L for alumina and alumina-supported materials, with a better fitting to the pseudo-second-order model.