Metal-organic framework (MOF)-based catalysts have become increasingly attractive for biodiesel production. Accordingly, MOF-808 was modified by sulfation with sulfuric acid to create a strongly acidic catalyst with enhanced performance for the esterification of oleic acid. To further tune the catalyst stability and kinetics, sulfated MOF-808 was grafted onto graphene oxide (GO), forming a MOF-808-SO4@GO composite. Catalysts' characterization analyses confirmed that sulfate groups were successfully introduced while MOF framework remained largely intact, resulting in an increase in both the strength and amount of acidic sites. Under optimal reaction conditions (120 °C, 3 h, methanol to oleic acid molar ratio of 30:1, and 5 wt% catalyst), MOF-808-SO4 achieved a superior biodiesel yield of 93.25%, while the GO-based composite also showed high performance, reaching 85.62%. Kinetic studies showed that the reaction was well described by a pseudo-first-order model. Importantly, introducing GO lowered the activation energy from 17.03 kJ/mol for MOF-808-SO4 to 13.17 kJ/mol for MOF-808-SO4@GO, indicating that GO support creates a more favorable kinetic environment by improving the accessibility of the acidic active sites. Reusability tests demonstrated that the composite catalyst exhibited superior stability and structural integrity resulting from strong interactions that GO formed with active catalytic species which prevented their leaching.
Biomass-assisted aquathermolysis is a promising strategy for in situ upgrading of heavy oil. Supported Ni–Mo/Al₂O₃ catalysts with different Ni/Mo molar ratios were synthesized and evaluated for the aquathermolysis of low-asphaltene Karamay heavy oil. Ni₃–Mo₇/Al₂O₃ showed the highest upgrading efficiency, owing to its favorable mesoporous structure, balanced acid strength distribution and suitable reducibility. The cooperative effect between corn stalk and Ni₃–Mo₇/Al₂O₃ was systematically investigated. Under the best conditions within the investigated range, a viscosity reduction rate of 57.34% was achieved with 2 wt% corn stalk and 1.5 wt% catalyst at 300 °C for 24 h. Group composition and elemental analysis indicated that corn stalk promoted the conversion of polar fraction into saturates, increased the atomic H/C ratio, and decreased sulfur and nitrogen contents. The average molecular weight decreased from 535.1 to 482.7 g·mol−1, and the boiling-range distribution shifted toward lighter fractions. 1H NMR indicated suppressed aromatization/condensation and increased aliphatic hydrogen. XPS revealed reaction-induced surface evolution of Ni3–Mo7/Al2O3, with lower-valence Mo and sulfide/oxysulfide species more evident in the corn-stalk-assisted system. GC–MS analysis of aqueous-phase products suggested that biomass-derived oxygenates may participate over NiMo active sites through hydrogen transfer, deoxygenation, and carbon-chain scission, thereby stabilizing radicals, suppressing secondary polycondensation, and enhancing upgrading.
Non-uniformity in flow rates, channel dimensions and catalyst loading among multi microchannels commonly arises during design, manufacturing, operation and measurement. Quantifying the tolerance thresholds of such non-uniformities is therefore of practical importance. In this paper, the complex interplay among flow maldistribution, channel dimensional variation, and catalyst loading heterogeneity is elucidated by distinguishing between packed-bed, washcoated, and thin-film microchannels. Mathematical approaches are developed to investigate the effects of non-uniformity among microchannels on residence time distribution (RTD), reaction performance, product selectivity, catalyst deactivation and thermal management under both isothermal and non-isothermal conditions. Results suggest that the effects of non-uniformity, particularly in flow rates, on Fischer-Tropsch synthesis (FTS) performance and catalyst lifetime are limited due to intrinsic performance compensation among channels. However, under insufficient temperature control, deviations in reaction performance are dominated by heat release and the resulting temperature rise, rather than solely flow maldistribution. Furthermore, non-uniformity in catalyst loading can significantly increase the risk of thermal runaway in the microchannel reactor system. The results highlight that the pursuit of perfectly uniform channel-to-channel distribution may be less critical than commonly assumed, whereas achieving and maintaining near-isothermal operation is of primary importance for safe and stable reactor performance.
The enhancement of ethylene yield via catalytic cracking presents a persistent challenge in addressing ethylene supply shortages. A series of bifunctional catalysts (La/P/HZSM-5) were prepared via simultaneous incorporation of lanthanum and phosphorus into HZSM-5 zeolite. The Py-IR analyses revealed that the simultaneous introduction of lanthanum and phosphorus resulted in a decrease in the Brønsted acid content of the La/P/HZSM-5 catalyst from the HZSM-5 (0.792 mmol/g) to 0.223 mmol/g. Further analysis of the structure-activity relationship between the catalyst and its performance reveals that the low Brønsted acid and porous structure effectively promotes the monomolecular decomposition of the cracking process. It was evident that the synergistic modification has resulted in the La/P/HZSM-5 catalyst demonstrating superior performance in n-octane cracking, with a cracking mechanism ratio (CMR) of 49.35. The balanced metal-acid functionality of the La/P/HZSM-5 catalyst was found to result in C2H4 yields of 31.23% from n-octane and 19.18% from diesel, representing increases of 31.11% and 50.20%, respectively, compared to the parent HZSM-5 (23.82% and 12.77%). The present work provided a theoretical foundation for the design of metal-acid bifunctional catalysts, with a view to improving ethylene production in catalytic cracking processes.
Steam-assisted gravity drainage bitumen requires extensive diluent addition or severe hydrotreating because of its high viscosity, density, acidity, sulfur content, and asphaltene-rich composition. Here, an experimentally validated process-intensified methane-assisted catalytic partial-upgrading strategy coupling methane pre-activation with off-gas recycle over Ce–Co–Ag–Ga–Mo/ZSM-5 was benchmarked against once-through methane operation using the same SAGD bitumen feed and catalyst. Recycling H₂- and C₂–C₄-containing off-gas generated an internally enriched gas phase associated with enhanced methane utilization and hydrogen-transfer chemistry without external H₂. Methane conversion increased from 1.1% to 9.5% while maintaining a 94.3 wt% liquid yield. Relative to the once-through product, viscosity decreased from 520 to 180 cP, density from 0.982 to 0.958 g mL−1, total acid number from 0.55 to 0.12 mg KOH g−1, sulfur from 2.4 to 1.5 wt%, and asphaltenes from 7.4 to 3.8 wt%. Simulated distillation showed that recovery below 400 °C increased from 48% to 63%. Post-reaction BET, TGA, Raman, XRD, NH3-TPD, pyridine-FTIR, and TEM characterizations indicated distinct deactivation pathways: once-through operation produced graphitic coke shells, pore blockage, and active-site agglomeration, whereas the intensified configuration preserved framework accessibility and formed thinner, disordered carbon. The strategy improves bitumen quality, methane utilization, and catalyst durability without external H₂.
The molecular structure of coal governs its chemical reactivity and behavior during combustion, pyrolysis, liquefaction, and gasification. Deciphering the structural evolution of coal is fundamental to unlocking its efficient utilization. In this study, a coal with vitrinite reflectance (Ro,ran) of 0.7% was selected and thermal simulation experiment was conducted to artifically advance the rank. With increasing temperature in thermal simulation experiments, the vitrinite reflectance of coal samples progressively rises, reaching 4.38% at 600 °C. The molecular structural characteristics of coal samples were analyzed via Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and confocal laser Raman spectroscopy. FTIR results indicate that coalification leads to the conversion of aliphatic side chains into aromatic ring structure, with a gradual increase in methylene-type side chains and progressive elongation of aliphatic side chains. XRD results reveal that the lateral size (La), stacking height (Lc), and interlayer spacing (d002) of coal molecules are 25.18–45.82, 14.40–35.61, and 3.43–3.59 Å, respectively. The d002 gradually decreases with increasing maturity. Although La and Lc values fluctuate owing to coalification jumps, they exhibit an overall increasing trend. Raman spectroscopy results indicate that the structural disorder degree of coal fluctuates during coalification, ultimately transforming into a highly ordered structure. Based on the molecular structural parameters of coal under different metamorphic pathways, the factors influencing coal molecular structures during metamorphism are discussed. The results reveal that temperature promotes hydrogen detachment from aliphatic side chains in coal, inducing carbon cyclization, and serves as the dominant control factor driving aromatic condensation growth and the cleavage of side chains/functional groups. Additionally, temperature progressively reduces methylene-type side chains and shortens aliphatic chain lengths. Time provides a kinetic buffer for dehydrogenation-cyclization reactions of aliphatic chains and C-H structural modifications in aromatic systems, facilitating their evolution toward thermodynamic equilibrium. As a secondary factor, pressure significantly influences physical structural parameters (La, Lc, d002).
The gasification of plastic-rich waste streams enables the conversion of non-recyclable materials into syngas to produce base chemicals, contributing to carbon circularity. Fluidized bed gasifiers allow the conversion of heterogeneous feedstocks while providing favorable syngas quality. The High-Temperature Winkler® (HTW®) process, combining a bubbling fluidized bed with a post-gasification zone (PGZ), is established for coal and biomass, but its application to plastic-rich waste streams remains challenging due to the high volatile content. This study demonstrates the technical feasibility of HTW® autothermal gasification of pelletized solid recovered fuel (SRF) during 155 h of operation in a 500 kWth pilot plant. The influence of the axial temperature profile (λ: 0.31–0.37; bed: 650–715 °C; PGZ: up to 840 °C) and the addition of olivine as external bed material on syngas quality and hydrocarbon formation was analyzed. The study identifies the PGZ as the key reaction zone governing hydrocarbon conversion and syngas upgrading. Optimized conditions yielded a syngas composition (dry) of 20 vol% H₂, 16 vol% CO, and 8 vol% CH₄. The lowest hydrocarbon loads obtained were 44 g/kgfeed aromatic hydrocarbons and 2.5 g/kgfeed gravimetric tar. The addition of olivine altered the temperature profile but did not improve performance.
Synthesizing anti-ammonia poisoning oxygen reduction reaction (ORR) electrocatalysts with low cost and high activity is pivotal for the development of high-performance direct ammonia fuel cells (DAFCs). ABO3-type perovskites are deemed as promising non-noble metal alternatives to noble-metal catalysts, thanks to their facile preparation, tunable structure and intrinsic ORR activity. Nevertheless, conventional ABO₃ perovskites synthesized via the sol-gel method are plagued by low specific surface area and severe particle agglomeration, which drastically suppress their practical ORR performance in DAFCs. Herein, one-dimensional (1D) La0.7Sr0.3MnO3 nanofibers were fabricated via PVP-assisted electrospinning to overcome the bottlenecks of traditional perovskite catalysts. Results demonstrate that the half-wave potential (0.76 V) and limiting-current density (5.78 mA cm−2) of La0.7Sr0.3MnO3 nanofibers are superior to those of the nanoparticle counterparts, which primarily benefits from its 1D porous structure enhancing the mass/electron transfer and exposing more active sites. The DAFC with a La0.7Sr0.3MnO3 cathode yields a peak power density of 40 mW cm−2, comparable to the DAFC using a Pt/C cathode. Moreover, the good stability of La0.7Sr0.3MnO3 nanofibers has been experimentally verified by the half-cell and whole-cell durability tests. This work confirms that 1D porous La0.7Sr0.3MnO3 nanofibers are a competitive non-noble-metal ORR catalyst, offering a feasible strategy for developing high-performance DAFCs.
The valorisation of combustion residues offers a sustainable route to support sustained development of biomass power plants. This study investigates the synthesis of Ca-enhanced porous carbons from biomass combustion residues sourced from Drax Power Station (UK) and post-consumer chicken eggshells. Unburnt biomass was selectively recovered through systematic drying, size fractionation, and ultrasonic treatment, producing a carbon-rich precursor with reduced inorganic contamination. The recovered biomass was systematically pyrolysed, Ca-enhanced, and activated to yield a structurally stable porous sorbent with a fixed carbon content of 61%. Raman analysis confirmed turbostratic carbon formation with consistent defect characteristics (ID/IG ≈ 0.65), while FTIR spectra showed substantial attenuation of lignocellulosic OH and CO functionalities following carbonisation. Surface enhancement was achieved via eggshell-assisted calcium incorporation through dry-mixing and Ca-ion impregnation, with the latter producing superior dispersion and controlled pore development. Subsequent physical activation demonstrated that CO2 activation outperformed steam activation, generating predominantly microporous carbons with a total accessible surface area of 463 m2 g−1, micropore surface area of 384 m2 g−1 and an estimated external surface area of 92 m2 g−1. The resulting surface area was comparable to those reported for several physically activated biomass-derived carbons while avoiding chemical activating agents.
Replacing traditional fossil fuels with carbon-free alternatives has become a crucial emission reduction strategy. Research on ammonia-diesel dual-fuel internal combustion engines is increasing. Nevertheless, studies focusing on the regulation of in-cylinder pressure traces to improve the combustion performance in ammonia-diesel dual-fuel engines are still scarce. This study therefore proposes a staged high-pressure injection strategy and numerically analyzes how its parameters affect combustion and emission characteristics. The results indicate that this strategy effectively improves diesel ignition efficiency and enables rapid, complete ammonia combustion. At high ammonia energy ratios of 60% and 70%, it significantly enhances combustion compared to direct blending. Furthermore, advancing the first injection timing resolves ignition delay, while adjusting the first injection quantity controls the pressure at top dead center. Shortening the second injection duration enhances the mixing of diesel spray with residual ammonia, promoting ammonia combustion and increasing peak cylinder pressure. For the engine model in this study, under a 70% ammonia energy ratio, the adjusted setting injects 40% of the diesel from −12 °CA to −9.48 °CA and the remaining 60% from −2 °CA to 1.02 °CA. Compared to the rated condition, this results in only a 0.23 °CA ignition delay, a 0.03 MPa lower top dead center pressure, and a 0.08 MPa lower peak pressure.
In this paper, the coordinated welfare-based operation of fuel-cell driven storage-enabled shared mobility for renewable-rich ECCs is considered. To this end, we design a distributed Stackelberg game-theoretic framework with blockchain-enhanced DT management that controls interactions in hierarchy between Shared Hydrogen Transportable (SHT) operator and Energy Communities with access to Shared Electrical Transportable (SET). The welfare-aware hydrogen and electricity exchange prices and dispatch are determined in the upper level, while the lower level obtains each community's optimal operation subject to privacy constraints by using the Alternating Direction Method of Multipliers. We consider uncertainty using a hybrid approach that incorporates stochastic programming, distributionally robust optimization with Wasserstein ambiguity sets, and Information Gap Decision Theory for low confidence signals. Scenario Generation and Reduction: employs a copula-based joint scenario generator and Kantorovich-Wasserstein planning, and critical security limits are imposed using chance-constrained formulations. A blockchain level is implemented for smart-contract settlements and security, and a DT maintains synchronism of cyber-physical states to underpin adaptive receding-horizon control. Results on tricommunity testbed demonstrate significant cost reduction, higher hydrogen penetration and better peak regulation performance compared to that if each community operates independently while guaranteeing the fairness of benefit distribution under an explicit social welfare constraint. Comparative analysis shows that SHT is superior to SET for multi-hour balancing because of decoupled electrolyzer–fuel-cell scheduling, smaller curtailment, and finer inter-period arbitrage. A refined analytic hierarchy process evaluates composite performance in economic, environmental, and operational dimensions and substantiates cost effectiveness as the most critical priority for ECC.
Lignin is an abundant renewable resource with high potential for the production of aromatic bulk and fine chemicals via hydrogenolysis. However, its efficient depolymerization remains challenging due to its structural complexity. In this work, the influence of functional groups on the palladium-catalyzed hydrogenolysis of benzyl aryl α-O-4 ethers serving as lignin model compounds, which have been considerably less studied in the literature than the commonly investigated β-O-4 compounds, was systematically investigated under mild reaction conditions. To broaden the substrate scope, new α-O-4 lignin model compounds were synthesized and analytically characterized. Kinetic studies revealed that both para-methoxy and especially para-hydroxy substituents on the benzyl moiety strongly decrease ether cleavage rates, providing insight into the limited cleavability of lignin, which contains substantial amounts of phenolic hydroxy groups. In contrast, ortho-methoxy substituents and para-propyl groups on the phenyl unit enhanced hydrogenolysis reactivity, while increasing methoxy substitution generally reduced reaction rates. Studies on more complex trilignols, including dibenzodioxocins, demonstrated selective α-O-4 bond cleavage, whereas β-O-4 linkages largely remained intact. Formation of phenolic para-hydroxy groups suppressed further depolymerization, highlighting the potential of controlled partial depolymerization combined with simultaneous lignin functionalization for targeted applications.
To address the flame geometry mismatch in applications such as high-altitude diesel burners, this study proposes a horizontal dual-nozzle jet configuration. The flame characteristics were experimentally investigated by systematically varying two key operational parameters: the global equivalence ratio and the fuel flow distribution between nozzles. A probability-based image processing method was employed to analyze flame evolution. The results quantitatively reveal the variation laws of dimensionless flame projection length, height, and uplift slope. Notably, the trends in flame fluctuation dimensions with global equivalence ratio are significantly affected by the auxiliary nozzle flow rate, with a distinct shift observed over an equivalence ratio interval as narrow as 0.15. Furthermore, based on Richardson number and Reynolds number, the flame regime is classified into a buoyancy-driven region, a chemistry-dominated region, and a strong turbulence dominates region. A comparison of dimensionless fluctuation parameters demonstrates that the vertical fluctuation parameter γ is a more suitable indicator for assessing flame stability than the horizontal parameter β. Finally, the study elucidates how the flame trajectory can be actively regulated by the secondary nozzle flow rate and the global equivalence ratio, identifying the parameter ranges over which trajectories converge. These findings provide fundamental data and theoretical support for achieving precise control of flame shape and stability in dual-nozzle burner systems.
Developing deep coal resources is often hindered by technical challenges and low chemical reactivity. Underground coal gasification, a key approach for exploiting medium to deep coal seams, suffers from low reaction efficiency. In this study, the regulatory mechanism of supercritical CO2 pre-treatment on gasification performance was investigated using multi-scale characterization. Results show that supercritical CO2 exposure transformed the coal surface from dense to loose, prompting the development of numerous multi-scale pores and fractures. Specifically, the micropore volume and specific surface area increased from 0.0364 cm3/g and 168.231 m2/g to 0.0365 cm3/g and 169.455 m2/g, respectively. Similarly, the mesopore volume and specific surface area rose from 0.0190 cm3/g and 3.717 m2/g to 0.0198 cm3/g and 4.113 m2/g. During high-temperature simulated gasification, the raw and modified coal exhibited similar initial weight loss (9.19% and 9.38%, respectively). However, during the medium-temperature pyrolysis stage (200–600 °C), the modified coal showed a higher cumulative weight loss (23.68%) than the raw coal (17.02%). Consequently, the residual carbon rate at 1000 °C decreased from 18.06% to 15.84%, indicating that supercritical CO2 modification promotes earlier volatile release and more complete gasification. Microscopic chemical evolution analysis indicated that the oxygen-containing functional groups were removed in the sequence: carboxyl group–ether bond/hydroxyl group–carbonyl group. The total content of these functional groups in the modified coal increased from 26.18% at 25 °C to 48.50% at 550 °C, before dropping to 34.24% at 600 °C. Concurrently, the proportion of aromatic carbon (C–C/C=C) reached 80.37%, notably higher than that of the raw coal (55.21%). In summary, supercritical CO2 promotes volatile release, lowers gasification activation energy, and enhances overall reactivity. This is achieved through the synergistic regulation of pore structure, surface oxygenated intermediates, and carbon skeleton reorganization, establishing a cohesive “pore–surface–chemical state” regulatory framework.
The influence of fuel physicochemical properties on injection and combustion processes is critical for the effective utilization of biodiesel in compression ignition applications. This study investigates the effects of palm biodiesel–diesel blending ratios on injection rate response and subsequent combustion characteristics under varying nozzle diameters and injection pressures while maintaining a constant injected fuel mass, thereby enabling physically consistent comparisons of intrinsic fuel-property effects in controlled oxygen-dilution conditions. Experiments were conducted using a Zeuch-type injection rate system and a constant-volume combustion chamber with palm biodiesel (B100) and its blends with diesel (B15, B30, and B60). Nozzles of 0.28, 0.30, and 0.35 mm were tested at injection pressures ranging from 400 to 1600 bar, with an ambient pressure of 45 bar and oxygen concentrations of 21%, 17%, and 13%. Results indicated that blends up to B60 exhibited injection rate profiles comparable to diesel. In contrast, the markedly higher viscosity of B100 (approximately 31.8% greater than diesel) led to a reduction in the quasi-steady injection rate, a delay in injection timing, and prolongation of the end of injection by about 14.3%, 21.7%, and 21.4%, respectively. Increasing biodiesel content shortened ignition delay by approximately 15.5% for B100 compared with B0, and lowered the peak heat release rate, attributed to its higher cetane number and lower distillation temperature. Higher injection pressure shortened injection duration and ignition delay but enhanced the injection rate and consequently increased both combustion pressure and heat release rate. Conversely, enlarging the nozzle diameter from 0.28 to 0.35 mm prolonged the ignition delay by approximately 21.83% for diesel and 45.12% for B100, while increasing the peak heat release rate. Increased exhaust gas recirculation (EGR) levels further extended ignition delay and diminished heat release. These findings provide insight into the role of fuel physicochemical properties in governing injection-controlled combustion, supporting the effective utilization of biodiesel in practical diesel combustion systems.
Controlled combustion of woody biomass from prunings can valorize Mediterranean agroforestry residues, but the particle size of the woodchips could influence energy yield and emissions. This study evaluates the effect of particle size on fuel quality, boiler efficiency, and emissions during the combustion of woodchips from olive and citrus prunings. The residues were chipped with 20 and 40 mm screens; a 50/50 mixture was also prepared for each species. The classes were characterized (moisture, ash, C–H–N, LHV) and combusted in an 80 kW boiler with a multicyclonic filter; gases (CO, CO₂, NOx, SO₂, O₂) and PM were continuously measured. Efficiency was calculated using the indirect method and analyzed with nonparametric tests; a PCA synthesized the emission profiles. Olive showed higher yields (73.1–78.1%) than citrus (54.2–69.3%) and lower concentrations of CO (1020–1879 vs 4229–9604 mg/Nm3) and SO₂ (4.4–10.2 vs 55.6–192.7 mg/Nm3), with lower NOx (522–609 vs 749–871 mg/Nm3). Within the tested size range (20 and 40 mm screens), nominal chip size did not significantly affect yield; however, mixed-size classes were associated with greater variability and, for citrus, greater dispersion of the emission profiles. PCA clearly separated the two species, highlighting greater emission stability in olive and greater variability in citrus.
The mixing of larger particles (e.g., fuel particles) in a bubbling fluidized bed is governed by buoyancy and drag, which correspondingly promote segregation and internal circulation. Prior studies have shown that gas released from such particles during drying or devolatilization can generate so-called endogenous bubbles, which exert an effective lift force on the particle. However, the impact of gas release under bubbling conditions and with over-bed particle feeding, remains unexplored. This study investigates how gas release influences the mixing of such particles in a bubbling fluidized bed. Experiments were conducted in a fluid-dynamically downscaled model simulating biomass pyrolysis at 700 °C in a bed of silica sand fluidized with flue gas using magnetic particle tracking and gas-releasing tracers. Different behaviors were observed depending on the fluidization velocity. At low fluidization velocities (u0/umf ≤ 2), buoyant particles sink slightly deeper by locally reducing the concentration of surrounding suspension, whereas heavy particles experience inhibited sinking resulting in preferred positions closer to the bed surface. As fluidization velocity increases beyond u0/umf ≥ 3.5, the effect of gas release on axial mixing diminishes, while the lateral mixing becomes more pronounced, with the dispersion coefficient enhanced by up to 40%. These findings inform industrial fluidized-bed design.
Ethanol is a promising biomass-derived renewable biofuel for internal combustion engines, offering substantial potential for carbon-emission reduction and knock suppression. This study combines experiments and numerical simulations to investigate the effects of engine oil on ethanol-gasoline combustion and emissions. Experiments were conducted to evaluate the influence of new and waste engine oil on flame temperature and ash morphology. A simplified kinetic model of engine oil, using C30H58 as a surrogate, was developed based on the HyChem method and coupled with an ethanol-gasoline sub-mechanism to establish a three-component mechanism suitable for CFD simulations. Three-dimensional simulations were then performed to examine the effects of ethanol and engine-oil blending ratios on in-cylinder combustion and soot formation. Results show that oil aging markedly deteriorates combustion completeness. The ethanol blending ratio exhibits a non-monotonic effect on combustion intensity: ratios ≥95% create an oxygen-rich environment that enhances combustion efficiency, whereas ratios <88% reduce oxygen availability, resulting in lower in-cylinder pressure and temperature. Engine oil addition increases pressure and temperature, shortens combustion duration, and strongly promotes soot formation; adding 6% engine oil increases soot emissions by 108.46% compared with pure ethanol. These findings support particulate-emission mitigation and the broader application of high-percentage renewable bioethanol fuels.
