This study investigates the adsorption and oxidation of asphaltenes onto nanoparticles. Six different metal oxide nanoparticles were employed, namely, Fe 3 O 4 , Co 3 O 4 , TiO 2 , MgO, CaO, and NiO. Batch adsorption experiments were carried out at different initial asphaltene concentrations. Asphaltene adsorption was evaluated by measuring the asphaltene concentration using thermogravimetric analysis, and adsorption kinetics and isotherms were obtained. For all the six nanoparticles, the isotherm data fitted well to the Langmuir model. Results showed that asphaltene adsorption is metal-oxide-specific and the adsorption capacities of asphaltenes onto the oxides followed the order CaO > Co 3 O 4 > Fe 3 O 4 > MgO > NiO > TiO 2 . Furthermore, oxidation of asphaltene was investigated after adsorption onto NiO nanoparticles. The oxidation temperature of asphaltene decreased by ∼140 °C in the presence of nanoparticles, showing their catalytic effect. The activation energies calculated by the Coats-Redfern method for asphaltene oxidation processes in the absence and presence of NiO nanoparticles were found to be approximately 100 and 57 kJ/mol, respectively. This study is a first step in showing the feasibility of using nanoparticles for asphaltene adsorption, followed by catalytic oxidation for heavy oil upgrading.

Nanotechnology is a rapidly growing technology with considerable potential applications and benefits. Among the numerous applications of nanotechnology for energy and the environment, adsorption, oxidation, and gasification/cracking of asphaltenes, a problematic constituent present in heavy oil, on nanoparticle surfaces are one of the most recent examples. In this work, three different types of metal oxide nanoparticles, namely, Fe2O3, Co3O4, and NiO, were selected for asphaltene adsorption and catalytic steam gasification/cracking. Adsorption and gasification of asphaltenes were studied using thermogravimetric analysis. The nanoparticles were found to be very efficient for asphaltene adsorption and catalytic steam gasification/cracking. Asphaltene adsorption affinity on the surface of nanoparticles followed the following order: NiO > Co3O4 > Fe2O3. The catalytic steam gasification/cracking of asphaltenes in the presence of nanoparticles followed the same order as well. The calculated percent conversion at the onset temperature for NiO, Co3O4, and Fe3O4 nanoparticles was 37, 32, and 21%, respectively. A relationship between adsorption affinity and catalytic activity is also found to exist.

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