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.

High asphaltene content in heavy crude oil normally generates adverse rheological properties that affect the flow through the reservoir, preventing optimal hydrocarbon production. It has been demonstrated that using nanoparticles may improve the mobility of oil. Nanoparticles may be used as adsorbents and catalysts in the oil industry for in situ upgrading. The main objective of this study was to investigate the sorption kinetics and the thermodynamic equilibrium for asphaltene sorption onto nickel and/or palladium oxides supported on fumed silica that was nanoparticulated at different times, temperatures, and concentrations. After adsorption, thermally cracked asphaltenes from Colombian crude oil were investigated using catalytic oxidation. The asphaltenes adsorbed onto the selected nanoparticles were subjected to thermal decomposition up to 700 °C in a thermogravimetric analyzer. This study was realized using an experimental design with a measured simplex–centroid of the three components by varying the wt % of the palladium and nickel oxides as well as the fumed silica as the support. The silica nanoparticles were characterized using N2 adsorption at 196 °C and X-ray diffraction. The Langmuir and Freundlich models were used to correlate the experimental sorption equilibrium data. The experimental asphaltene adsorption isotherm data were adequately adjusted using the Freundlich model. The adsorption of asphaltenes on NiO and/or PdO supported on fumed silica was much higher than that over fumed silica over the range of the tested equilibrium concentrations. Pseudo-first- and pseudo-second-order kinetic models were applied to the experimental data obtained at different asphaltene concentrations from 100 to 1500 mg/L for the virgin fumed silica (S) and fumed silica-supported materials (SHSs); better fits were found for the pseudo-second-order model. However, the nanoparticles significantly decreased the asphaltene decomposition temperature and activation energy. The catalyst kinetics was calculated using the Ozawa–Flynn–Wall Model (OFW). All of the nanoparticles demonstrated high catalytic activity toward asphaltene decomposition in the following order at 0.2 mg/m2 asphaltene concentration on nanoparticle surfaces: SNi1 < SNi1Pd1< SNi0.66Pd0.66 < SPd1 < SPd2 < SNi2 < S. Consequently, using nanoparticles significantly enhanced the thermal decomposition of asphaltenes, improving the mobility of heavy oils in situ.

The deposition of asphaltenes is one of the most difficult problems to overcome in oil production and processing. The presence of asphaltenes in crude oil, and consequently, the adsorption and deposition of asphaltenes on the rock surfaces, affects the rock properties, such as porosity, permeability, and wettability. This study aims at analyzing the effect of the chemical nature of 12 types of nanoparticles on asphaltenes adsorption; hence, the delay or inhibition of deposition and precipitation of asphaltenes on porous media under flow conditions at reservoir pressure and temperature were investigated. The adsorption equilibrium of asphaltenes onto nanoparticles was effectively achieved within relatively short times (approximately 2 min), which indicates the promising nature of adsorbents for delaying the agglomeration and inhibiting the precipitation and deposition of asphaltenes. The adsorption equilibrium of asphaltenes for the nanoparticles was determined using a batch method in the range 150–2000 mg/L. The equilibrium adsorption data were fit to both the Langmuir and Freundlich models. Additionally, in this study, the transport of nanoparticles in a porous media at a typical reservoir pressure and temperature was investigated. As a result, the use of nanoparticles allowed the system to flow successfully, which demonstrated the inhibition of precipitation and deposition and the enhanced perdurability against asphaltene damage in the porous media.

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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NiWMo submicronic catalysts from emulsified metallic aqueous solutions were tested for Athabasca bitumen upgrading. The experiments were performed in a batch reactor (100 mL capacity) at a total pressure of 3.45 MPa, a stirring speed of 500 rpm, reaction times of 3−70 h, and temperatures from 320 to 380 °C. Ultradispersed (UD) catalysts enhanced the upgrading of Athabasca bitumen by increasing the hydrogen/carbon ratio and reducing both viscosity and coke formation. The conversion of bitumen increased with both the temperature and reaction time, whereas viscosity, sulfur, and microcarbon residue (MCR) in the reaction products decreased. Catalytic particles tend to agglomerate and become incorporated within the incipient coke matrix that develops at a residue conversion beyond 50 wt %. Nevertheless, good properties of upgraded oil (API gravity, 16°; viscosity at 40 °C, 60 cP; and MCR, 11.1 wt %) are obtained during processing before the onset of solids precipitation.

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