One major challenge often encountered during the production and transportation of crude oil in petroleum industries is the formation of extremely stable emulsions. This problem is particularly present during the production of heavy oils where steam is used to reduce the viscosity of heavy oil or where submersible pumps are used to artificially lift the produced fluids. This review elaborates on the mechanism of the formation and stability of heavy oil emulsions, discusses the effect of natural surfactants (resins, asphaltenes, solid particles, etc) on the stability of heavy oil emulsions, and summarizes the prominent and sustainable technological and methodological developments in the demulsification of heavy oil emulsions from an economical and environmental perspective. Ionic liquids have been reported as efficient and environmental demulsifiers, and the latest research results on this topic are discussed. Microwave and ultrasonic demulsification methods have been reported to be effective in treating heavy oil emulsions and are also recommended as substitutes in the further development of demulsification technology for treating heavy oil emulsions.

The significant aspects in the downhole catalytic cracking upgrading and viscosity reduction of heavy oil are to develop industrial hydrogen donors with a strong hydrogen supply effect, abundant sources, reasonable price, and environmentally friendly nature.

This study systematically investigates the effect of temperature on product distribution and reaction mechanisms during the pyrolysis of oil shale through thermogravimetric analysis (TG) and fixed-bed pyrolysis experiments. The results indicate that the oil shale pyrolysis process can be divided into three stages: the low-temperature stage, dominated by water evaporation; the mid-temperature stage (400–650 °C), which is the primary stage for organic matter decomposition; and the high-temperature stage (> 650 °C), characterized by secondary cracking of heavy components and decomposition of mineral residues. The study reveals that temperature significantly influences the generation and distribution of gas, liquid, and solid products. Gas yield increases markedly under high-temperature conditions, especially for H₂ and CH₄. The shale oil yield reaches its peak at mid-temperatures (400–500 °C), but decreases at higher temperatures due to secondary cracking reactions. The fixed carbon content of the semi-coke decreases with increasing temperature, while the mineral components decompose into porous oxides at high temperatures. Kinetic analysis demonstrates that primary reactions drive the mid-temperature pyrolysis, whereas secondary reactions enhancing gas production become dominant at high temperatures. This study elucidates the regulatory mechanisms of temperature on oil shale pyrolysis behavior, providing guidance for the targeted optimization of specific products, such as gases, shale oil, or semi-coke. The findings offer scientific and technical references for optimizing pyrolysis processes and improving the efficient utilization of unconventional energy resources.

For solving the problem of low efficiency about dyes and slow precipitation rate for powdered activated carbon (PAC), this study successfully prepares a kind of powdered activated carbon-based composites (PACMC) to remove Rhodamine B (RhB) in wastewater as an adsorbent. PACMC derived from potassium humate and polyaluminium chloride (PACl)-modified PAC were fabricated via a chemical precipitation method. We confirmed the micro-morphology and chemical composition of PACMC by scanning electron microscopy energy-dispersive X-ray spectrometer (SEM-EDS) and fourier infrared spectroscopy (FT-IR), certifying that PACMC was synthesized by chemical reaction of raw materials. PACMC has layered porous structure and functional groups, which is beneficial to the transport and diffusion of RhB molecules. The specific surface area (10.098 m²·g⁻¹) and average particle size (142.9 µm) of PACMC and the specific surface area (710.1 m²·g⁻¹) and average particle size (11.9 µm) of PAC were measured. By comparison, it can be seen that PACMC has larger average particle size conducive to solid–liquid separation. The static adsorption experiments were carried out to investigate the adsorption properties of RhB by PACMC. The results showed that the adsorption capacity of PACMC for RhB was 2–3 times as high as that of PAC. The pH value of the solution had a significant effect on the adsorption of RhB by PACMC and the maximum adsorption was observed at pH = 4.5 (q_e = 28.56 mg·g⁻¹, C₀ = 40 mg·L⁻¹). The adsorption of RhB by PACMC can be well described by the pseudo-second-order kinetics. The kinetic results revealed that the adsorption process involved several steps, where the chemical adsorption and intra-particle diffusion both played the important roles. The isothermal adsorption data were in accordance with the Dubinin–Radushkevich model, which indicated that the adsorption was dominated by the chemisorption mechanism. Therefore, the adsorption mechanisms included chemical binding/chelation effect and electrostatic adsorption effect.