Energy & Fuels最新文献

The energy transition and global petrochemical market are striking factors reshaping the view of a future refinery. Traditionally known as major producer of fuel to power energy machinery and transport vehicles, today’s refineries are refocusing their technologies toward maximum production of petrochemicals. The major drivers for this restructuring are economic and environmental factors, which are the primary sources of uncertainty in future fuel demand. In this Highlight, the challenges and opportunities that await future refineries are discussed. Future refineries must rethink crude oil processing, and it is worth mentioning that many conventional refineries have already been integrated with petrochemical plants. New technologies for the direct conversion of crude oil to chemicals are being publicized, with some of them reaching commercialization level. To drastically reduce greenhouse gas emissions, refineries need to implement renewable energy sources, process automation, low-carbon hydrogen, and carbon capture, utilization, and storage (CCUS) along with refinery waste recycling. Despite advancements in implementing these new refinery configurations, challenges remain in developing new catalyst formulations for the direct conversion of crude oil to chemicals (COTC) as well as in addressing infrastructure demands for safely transporting and stationing renewable energy sources. The future of the refining industry will increasingly depend on its ability to transition from a fuel provider to an integrated fuel and chemical producer. The successful integration of AI-driven optimization, waste conversion and coprocessing, CCUS, and next-generation COTC catalysts will be key elements of the emerging era of industrial decarbonization.

Shale reservoirs present major challenges for enhanced oil recovery (EOR) due to extreme nanoscale confinement within their pores. This study demonstrates a nanofluidic experimental platform that enables direct visualization of surfactant-assisted oil displacement in 10 and 100 nm channels. Two nonionic surfactants with distinct molecular structures were evaluated: Surfactant A (12 ethoxylate, 16 methylene) and Surfactant B (18 ethoxylate, 22 methylene). Dynamic light scattering (DLS) revealed micelle diameters of 8.7 and 18.9 nm for Surfactants A and B, respectively. In 10 nm channels, Surfactant A achieved 71.3% oil displacement at 10× CMC, compared to 57.6% for Surfactant B, while both achieved complete recovery in 100 nm channels. The superior performance of the smaller-micelle surfactant highlights the critical role of molecular aggregation and confinement effects in controlling nanoscale transport and interfacial dynamics. These findings establish a direct mechanistic link between micelle size and EOR efficiency, providing new insight into the design of surfactant formulations for oil recovery from ultratight formations.

Diesel fuel is essential intercontinentally, as it plays critical roles for industry, agriculture, military, and healthcare sectors. Hence, the storage stability of diesel is an essential aspect of maintaining daily operations globally. As the nitrogen-containing compounds (NCCs) are known to facilitate storage stability failure of diesel, their chemical characterization is vital. In this work, (+) electrospray ionization coupled to an orbitrap mass spectrometer was employed to qualitatively characterize ionized NCCs derived from stable and unstable diesels, and from sediment obtained from the unstable diesel fuel. Remarkably, up to 40 and 63 individual homologue ion series (ions sharing the same general molecular formula, each representative of at least one chemical class (e.g., pyrroles, quinolines, carbazoles)) were detected in diesel fuel and sediment, respectively. Hence, this work provided more comprehensive qualitative information for diesel fuels and sediments than previously documented. Upon comparison of diesel fuels, important compositional differences were observed, notably greater abundances of NCCs with the general formula of C_xH_yNO and C_xH_yNO₂ in the unstable diesel. Upon analysis of sediment, ions of the general formula of C_xH_yN, C_xH_yNO, C_xH_yNO₂, C_xH_yNO₃, and C_xH_yN₂O₂ were detected. Interestingly, NCCs of smaller alkyl carbon number showed greater propensity to contribute to sediment formation. Additional stress studies using ASTM D5304 were completed on copper-doped and nondoped diesel fuels. Upon stressing the nondoped and copper-doped stable diesel fuels, oxidized NCCs clearly increased in abundance, especially for the copper-doped diesels, demonstrating its significance for accelerating oxidative reactions. Additional qualitative data was reported for the NCCs detected in fuels and sediments and by individual ion series (i.e., range and average molecular masses) as well as Kendrick Mass Defect plots. Overall, the reported qualitative information showcased the proficiency of the orbitrap at providing vital information for enhancing our current understanding of diesel storage stability.

Hydrogen is increasingly recognized as a key energy carrier in the transition toward carbon neutrality due to its high specific energy and zero direct carbon emissions. However, its distinct combustion properties, especially the high laminar burning velocity, make premixed hydrogen flames highly susceptible to flashback, which threatens the safety of practical burners. This study investigates the mechanisms of flashback suppression and promotion under gradient magnetic fields using a two-dimensional multislit burner model that incorporates detailed chemistry, conjugate heat transfer, nonunity Lewis numbers, and the Soret effect. Baseline simulations show that reducing inlet velocity or increasing equivalence ratio intensifies near-wall preheating and hydrogen enrichment, reorganizing the flame into a boundary-layer-anchored structure where the flame root dominates propagation behavior, thereby lowering the flashback limit. When a gradient magnetic field is applied, the Kelvin force─strongest in the oxygen-rich, cooler core flow─redistributes momentum and steepens the near-wall velocity gradient. With upstream placement, the core flow is decelerated while boundary-layer velocity increases, enhancing convective wall cooling and displacing the flame base downstream, which reduces near-wall heat-release density and lowers the flashback propensity. In contrast, downstream fields accelerate the core flow, reduce near-wall cooling, elevate wall temperature, and promote upstream flame propagation, which facilitates flashback. Strong fields can also activate a core-flashback mode distinct from boundary-layer mechanisms. Therefore, appropriate placement and strength of gradient magnetic fields offer a nonintrusive strategy to suppress boundary-layer flashback via Kelvin-force-driven momentum redistribution, supporting safer, more efficient hydrogen combustion.

The Cenozoic continental reservoir of the Bozhong 25-1 Oilfield in the Bohai Bay Basin is a typical low-porosity and low-permeability tight sandstone, which is prone to causing severe water lock after hydraulic fracturing. Supercritical CO₂ (SC-CO₂) prepad fracturing can mitigate water blocking through mineral dissolution and replacement effects, but its influence mechanism on the physical properties of offshore low-permeability tight reservoirs after fracturing fluid invasion remains unclear. Core-scale microscopic characterization and physical simulation experiments were conducted to investigate the dynamic evolution characteristics of SC-CO₂ invasion, the impact of SC-CO₂ on rock properties after fracturing fluid interaction, and the effect of SC-CO₂ prepad fracturing on oil-phase permeability. The results indicate that SC-CO₂ exhibits a nonuniform frontal advance during core invasion, with the invasion velocity increasing with pressure. The recovery rate of water-blocking damage caused by the fracturing fluid reached 21.61%. NMR analysis revealed improved pore-throat structure and a 16.46% increase in movable water content postreaction. Oil-phase permeability increased with higher initial core permeability, flowback velocity, temperature, and SC-CO₂ injection volume. Compared with conventional hydraulic fracturing, SC-CO₂ fracturing enhanced the oil-phase permeability by 14.97%.

Permeability is a crucial factor in the gas production of natural gas hydrates, significantly influenced by the saturation and distribution of hydrates. In this study, a high-pressure visual microchip system is developed that enables in situ observation of hydrate formation/dissociation while simultaneously measuring permeability. The experimental results demonstrate that hydrate morphology is strongly influenced by the initial gas–water distribution, leading to distinct permeability responses. Four contact patterns are identified: when gas bubbles are dispersed in the water phase, hydrates form around the bubbles; when small water droplets are dispersed in the gas phase, only limited hydrate forms on one side of each droplet; when extensive gas–water contact occurs, hydrates grow abundantly within the gas phase; when only water is present, no hydrate forms. Furthermore, a variation coefficient (CV_Sh) is defined to characterize the spatial heterogeneity of hydrate saturation. During hydrate dissociation, permeability exhibits a two-stage behavior, with a gradual increase at the early stage followed by a rapid recovery at the later stage. This behavior is closely associated with the evolution of CV_Sh, where increasing CV_Sh indicates enhanced hydrate heterogeneity and suppresses the extent of permeability increase.

The combination of low-salinity brine injection and surfactant flooding was shown to significantly enhance oil production in oil-wet systems, yet the direct pore-scale transport mechanisms responsible for the additional recovery are still not well understood. In this study, we employ a micro-CT scanner to directly probe the pore-scale fluid configurations, local displacement patterns, and in situ contact angles under reservoir conditions. Specifically, we investigate the flow of different wetting fluid systems through a set of dynamically aged miniature limestone core samples after addition of the surfactant and alteration of salt concentrations in the formulated brine solutions. Characterization of local wettability reveals an accelerated reversal from oil-wet toward neutral-wet for the low-salinity surfactant injection compared to that of either low-salinity waterflooding or surfactant flooding alone. The in situ contact angles change significantly with the injection of even small pore volumes of low-salinity surfactant solution, and the effect is even more profound when the injection follows a low-salinity waterflood. The main mechanism responsible for the observed oil recovery enhancement appears to be the invasion of the brine front into smaller pores and corners of the pore elements, which is facilitated by the rapid wettability reversal induced by the low-salinity surfactant injection.

Micropores contribute the majority of surface area in coal and play crucial roles in the storage of coalbed methane. However, although various methods have proven the existence of a large number of micropores in coal, due to the extremely small size of these micropores (<2 nm), very few studies have captured images of these micropores to visualize them. This study employed double spherical aberration-corrected scanning transmission electron microscopy (DS-AC-STEM) to visualize micropores in bituminous coal (LJT) and anthracite (BLS) samples. Compared with conventional microscopy, DS-AC-STEM provides extremely high magnification (>5 million times), enabling clear observation of the rough surfaces and abundant micropore structures in the coal samples. Using carbon 13 nuclear magnetic resonance (¹³C NMR) and Fourier transform infrared spectroscopy (FT-IR) experimental data, combined with molecular characterization results, three-dimensional pore system molecular structures were constructed for both LJT and BLS coals. The micropore distribution derived from the molecular models showed strong agreement with experimentally measured pore volumes, with all deviations within 0.005 cm³/g. The constructed pore models exhibit rough surfaces and distinct pore structures, resembling the DS-AC-STEM images of the actual coal samples. Through micropore imaging characterization and pore structure reconstruction, this study presents the coal micropore structure in the form of three-dimensional molecular models. This approach contributes to understanding the storage and migration mechanisms of gases such as methane within coal micropores.

In China, coal-fired power generation remains the primary source of CO₂ emissions. Partially substituting coal with ammonia (NH₃) as a fuel has been recognized as a feasible strategy for reducing the emissions of CO₂ from power generation. Most existing studies mainly focus on the ammonia cocombustion behavior of single coal, relatively little attention has been paid to the ammonia cocombustion behavior of blended coals. However, due to rising coal prices and uneven coal resource distribution in China, coal blending has been widely adopted in Chinese thermal power generation, investigating the behavior of blended-coal/ammonia cocombustion is of greater practical significance. Therefore, this study investigates the kinetic synergistic mechanism of blended-coal/ammonia cocombustion through isothermal thermogravimetric experiments and atomistic-labeling-based molecular dynamics simulations. The results indicate that ammonia exerts a stronger inhibitory effect on the combustion rate of bituminous coal than on lignite. Furthermore, ammonia cocombustion with lignite produces a larger amount of OH radicals, which further enhance the combustion of ammonia than in bituminous coal/ammonia systems. However, the synergistic interactions between coal and ammonia are weakened at higher temperatures. Positive synergistic effects are observed for the O₂ consumption and CO₂ generation in blended-coal/ammonia cocombustion, and the addition of ammonia enhances this synergistic effect. Specifically, the combustion rate, O₂ consumption, and the generation of CO₂ of bituminous coal are promoted, whereas those of lignite are inhibited. Further analysis of the reaction pathways revealed that ammonia alters the intrinsic oxidation routes of coal molecules.

The ZIF-8 adsorption-hydration method is regarded as a highly promising technology for methane storage. However, the high temperatures required for ZIF-8 desorption and the slow growth rate of methane hydrate has become unsatisfactory in current production. In this study, the behavior of ZIF-8 adsorption-hydration for methane storage and release under a cosine-oscillating electric field was systematically investigated via molecular dynamics simulations. The results indicate that an electric field of 1 V/nm at 8 THz can effectively promote methane desorption from ZIF-8. Under 273 K and 0.1 MPa, the residual fraction of methane in ZIF-8 after desorption decreased from 77.7% to 5.4%. In addition, the electric field influences hydrate growth by modulating hydrogen bonding between water molecules, and, at each field strength, there is a frequency window that promotes hydrate formation. High-frequency fields disrupt the hydrogen bonds within the hydrate phase, accelerating decomposition. Fields with suitable frequency disrupt hydrogen bonds in the liquid, improving gas–liquid interaction and facilitating hydrate formation. By applying an intermittent electric field of 1 V/nm at 4 THz, high-speed, stable methane-hydrate growth was achieved, with a growth rate five times that of a control system without an electric field. These findings elucidate, at the molecular scale, the mechanism by which a cosine-oscillating electric field governs methane storage and release in the ZIF-8 adsorption-hydrate method and provide theoretical guidance for developing efficient methane storage and transport technologies.