Intensification of the steam stimulation process using bimetallic oxide catalysts of MFe2O4 (M = Cu, Co, Ni) for in-situ upgrading and recovery of heavy oil

In this study, bimetallic catalysts based on transition metals CuFe2O4, CoFe2O4 and NiFe2O4 are proposed for catalyzing aquathermolysis reaction during steam-based EOR method to improve in-situ heavy oil upgrading. All upgrading experiments were carried out under a nitrogen atmosphere for 24 h in a 300-ml batch Parr reactor at 250 and 300 °C under high pressure 35 and 75 bar, respectively. To evaluate the catalytic performance of the bimetallic catalysts used, comprehensive studies of changes in the physical and chemical properties of the improved oils, including the viscosity, elemental composition and SARA fractions of oils before and after upgrading processes were used. Furthermore, individual SARA fractions were characterized in detail by Gas Chromatography (GC), High-Performance Liquid Chromatography (HPLC) and Carbon-13 Nuclear Magnetic Resonance (13C NMR), respectively. The results showed that bimetallic catalysts have high catalytic performance at 300 °C for the upgrading of heavy crude oil in viscosity reduction, increasing the amount of saturates (especially alkanes with low carbon number) as a result of thermal decompositions of high molecular weight compounds like resin and asphaltenes leading to their increasing. Furthermore, the upgrading performance is reflected in the improvement of the H/C ratio, the removal of sulfur and nitrogen through desulfurization and denitrogenation procedures, and the reduction in polyaromatic content, etc. CoFe2O4 gives the best performance. Generally, it can be concluded that, used bimetallic based catalysts can be considered as promising and potential additives improving in-situ upgrading and thermal conversion the heavy oils.

Inhibitory action of halogen-free fire retardants on combustion and volatile emission of bituminous components

The objective of this study is to quantitatively evaluate inhibitory action of halogen-free fire retardants (HFR) on combustion properties and volatile emission of such bituminous components as saturates, aromatics, resins, and asphaltenes (SARA). Thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR) tests were performed on SARA fractions containing matched fire retardants, respectively, and thermal kinetics parameters based on TG curves and functional and structural indices from FTIR spectra were calculated, respectively. The selected fire retardants have not affected the combustion process of SARA fractions, but the combustion temperature intervals are elevated and combustion progresses are retarded. Also, the char yields of SARA fractions are obviously increased by the matched fire retardants, improving their heat stability. The activation energy is elevated because of the added fire retardants, indicating combustion resistance of SARA fractions become larger. Additionally, the matched fire retardants inhibit the toxic gas emission in the combustion process of SARA fractions, but have few effects on gaseous product constituents. H2O and CO2 are identified as two typical released gases in various combustion phases of each SARA fraction. Finally, the added hydroxide play a role of fire retardants through cooling, dilution, adsorption, and neutralization, and the generated active oxide facilitates the expandable graphite (EG) and matrix to form densified and thick carbon layer. These suppress the volatile emission, and hinder the heat conduction and oxygen supply. Fire retardant composite exhibits the synergistic effect of fire retardancy and smoke inhibition in the combustion process of SARA fractions.

Polymer-Bitumen Interaction: A Correlation Study with Six Different Bitumens to Investigate the Influence of SARA Fractions on the Phase Stability, Swelling, and Thermo-Rheological Properties of SBS-PmB

The aim of this work is to determine the influence of the bitumen chemistry on the rheological performance of bitumen and polymer modified bitumen (PmB), as well as the polymer distribution and storage stability. Six different bitumens and their 5 wt.% SBS mixtures are considered in this work. The bitumen composition was determined by SARA fractioning, which was then correlated with the glass transition temperature, complex modulus |G*|, and phase angle, which were obtained by parallel-plate dynamic shear rheology in the temperature range of −25 to 65 °C. The polymer distribution, which was derived from fluorescence microscopy images and the storage stability (determined by tube test) also correlated with the SARA fractions. It was found that the saturates decrease |G*| and Tg and increase the phase angle in crude bitumen, while the asphaltenes increase |G*| and the phase angle. For PmB, the amount of swelling was determined by the saturate content of bitumen. The glass transition temperature of PmBs increases for low saturate and decreases for high saturate contents. |G*| and the phase angle of PmBs correlates with the saturate content, with a varying influence depending on a high or low saturate content and the temperature range due to saturate depletion in the bitumen-rich phase and the varying vol% polymer-rich phase. The aromatic and resin fractions show no correlation in the considered bitumens and PmBs.