Fuel最新文献

{"title":"Optimized continuous flow water removal from biodiesel and diesel (B15) using raschig ring-shaped polyacrylamide/cellulose microfibrils hydrogels in fixed-bed columns","authors":"Letícia Arthus ,&nbsp;Allan Pétris Angeli ,&nbsp;Maria Regina Wolf Maciel ,&nbsp;Leonardo Vasconcelos Fregolente","doi":"10.1016/j.fuel.2025.136332","DOIUrl":"10.1016/j.fuel.2025.136332","url":null,"abstract":"<div><div>The rising biodiesel content in diesel, driven by global policies, intensifies the challenge of maintaining fuel quality, particularly regarding water content. Elevated water levels in fuels can cause mechanical failures, corrosion, microbial growth, and reduced fuel performance, leading to increased maintenance costs and environmental concerns. Composite hydrogel packings offer significant potential for fuel dehydration, particularly in continuous processes, where essential characteristics include robust mechanical strength, high hydrophilicity, rapid kinetics, and geometry that facilitates fluid flow without causing pressure drops. This study addresses these challenges by employing hydrolyzed and non-hydrolyzed PAM/MFC (polyacrylamide/cellulose microfibrils) hydrogels, shaped into Raschig rings, as packing materials in fixed-bed columns for continuous water removal from biodiesel and B15 diesel (diesel fuel containing 15 % (v/v) of biodiesel). For biodiesel, hydrolyzed PAM/MFC reduced water content from 952.8 ppm to 463.6 ppm (51 % removal) after a 2.3-hour residence time, meeting EN 14214 standards. When connected in series with a column containing hydrolyzed and lyophilized PAM/MFC hydrogels, water content was further reduced to approximately 350 ppm. Hydrolyzed PAM/MFC maintained performance over seven cycles, including four with regenerated material, demonstrating its reusability and durability. Conversely, non-hydrolyzed PAM/MFC hydrogels removed 40 % of water during a 2.3-hour residence time, highlighting the need for anionic hydrogels to achieve faster water removal kinetics from biodiesel. For B15 diesel, the same non-hydrolyzed material achieved a 36 % reduction in 17 min of residence time, lowering water content to below 200 ppm, in compliance with EN 590 standards. This study also optimized the production of Raschig ring-shaped hydrolyzed PAM/MFC hydrogels, demonstrating the feasibility of reusing the twice, reducing specific sodium hydroxide consumption by approximately 44 %. Additionally, washing hydrolyzed hydrogels in a cascade system significantly improved washing efficiency. An economic evaluation revealed that hydrolyzed PAM/MFC hydrogels provided a cost advantage over other anionic hydrogels with similar performance in removing water from biodiesel, being 17 % and 50 % less expensive than acrylamide-sodium acrylate copolymers and sodium polyacrylate hydrogels, respectively. Overall, this study presents a scalable and technically viable solution for industrial fuel dehydration, offering an integrated approach that combines operational efficiency in packing production and compliance with global fuel quality standards.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"404 ","pages":"Article 136332"},"PeriodicalIF":6.7,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144695376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental and kinetic modeling study on laminar burning velocities and ignition delay times of NH3/PODE3 blends","authors":"Jianshu Mao,&nbsp;Xiao Ma,&nbsp;Zhi Wang,&nbsp;Hongming Xu,&nbsp;Shijin Shuai","doi":"10.1016/j.fuel.2025.136317","DOIUrl":"10.1016/j.fuel.2025.136317","url":null,"abstract":"<div><div>Ammonia–polyoxymethylene dimethyl ether 3 (PODE₃) dual fuel mode shows great potential in enhancing ammonia combustion performance, reducing carbon-related and pollutant emissions, and promoting the widespread application of ammonia-fueled engines. In this study, the ignition delay times (IDTs) of NH₃/PODE₃ blends were measured using a rapid compression machine (RCM) within a wide temperature (T_eff) range at elevated pressures (P_eff). Moreover, the laminar burning velocities (LBVs) of NH₃/PODE₃ blends were determined employing a constant-volume combustion vessel at wide initial pressures, temperatures, and ammonia molar ratios (AMRs). The outcomes demonstrate that the incorporation of PODE₃ conspicuously shortens the IDTs and augments the LBVs of NH₃. Based on these data, a detailed chemical reaction mechanism for NH₃/PODE₃ blends has been developed, encompassing 319 species and 2015 reactions. This proposed mechanism was meticulously validated against IDTs, LBVs, and major species mole fraction profile data over an extensive spectrum of experimental conditions, covering not only pure NH₃ and pure PODE₃ but also NH₃/PODE₃ blends with diverse ammonia fractions. The results evince a high degree of prediction accuracy when applying this mechanism, thereby corroborating the efficacy and appropriateness of the mechanism for CFD simulations in NH₃–PODE₃ dual fuel engines. Pathway analysis and sensitivity analysis were also conducted. The results demonstrate that the H-abstraction reactions of PODE₃ by NH₂ radical, R9: PODE₃ + NH₂=PODE₃B + NH₃ and R10: PODE₃ + NH₂=PODE₃A + NH₃, are sensitive only under the condition of AMR = 92.5 % and 1.5 MPa with respect to IDTs. The chain branching reactions, R#1: O₂ + H = O + OH, exhibits the highest sensitivity coefficients for LBV. The NNH radical plays a crucial role in both IDTs and LBVs of NH₃/PODE₃ blends, whereas the CH₃ radical is more prominent at rich regime for LBVs. The results further indicate that increasing AMR can enhance the flame stability of NH₃/PODE₃ blends.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"404 ","pages":"Article 136317"},"PeriodicalIF":6.7,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144703396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Direct synthesis of cyclohexanone via transfer hydrogenation of cyclohexanol and phenol over Ni-based catalysts","authors":"Alexey A. Philippov,&nbsp;Veronika M. Anufrieva,&nbsp;Damir E. Nasokhov,&nbsp;Vera P. Pakharukova,&nbsp;Tatiana S. Glazneva,&nbsp;Oleg N. Martyanov","doi":"10.1016/j.fuel.2025.136376","DOIUrl":"10.1016/j.fuel.2025.136376","url":null,"abstract":"<div><div>A novel and promising process for synthesizing cyclohexanone, a precursor of polyamide synthesis, via the comproportionation of phenol and cyclohexanol has been investigated. This process was studied within the temperature range of 200–300 °C with the initial substances being used in stoichiometric ratio. The Ni/Al₂O₃ catalysts, which were prepared using the deposition–precipitation method and characterized by ICP–AES, XRD (including in situ investigation), N₂ adsorption–desorption, H₂-TPR, CO pulse adsorption, and FTIR spectroscopy, were employed in this study. The present study established a correlation between conversions of phenol and cyclohexanol into cyclohexanone over Ni/Al₂O₃ catalysts and the accessible Ni⁰ surface area. Furthermore, kinetic analysis of the experimental data has demonstrated that the suggested Ni-based catalysts exhibit high activity in the explored process.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"404 ","pages":"Article 136376"},"PeriodicalIF":6.7,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144703427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nanoscale simulation of ice melting behavior and thermal conductivity characteristics of catalyst layers in proton exchange membrane fuel cells using the lattice Boltzmann method","authors":"Hao Wang,&nbsp;Lingquan Li,&nbsp;Guogang Yang,&nbsp;Naibao Huang","doi":"10.1016/j.fuel.2025.136331","DOIUrl":"10.1016/j.fuel.2025.136331","url":null,"abstract":"<div><div>The cold start issue of fuel cells is critical due to the risk of ice formation within the catalyst layer at low temperatures, posing significant challenges to efficient operation and requiring effective thermal management strategies. In this paper, the ice melting process in the catalyst layer is simulated using the enthalpy-based lattice Boltzmann method (LBM). Catalyst layer structures with varying Pt/C mass ratios, ionomer contents, and carbon sphere radius are generated through random reconstruction. The effects of these parameters on heat transfer efficiency and ice melting speed are analyzed. The results indicate that higher Pt/C mass ratios, higher ionomer contents, and smaller carbon sphere radius are found to significantly enhance heat transfer performance and ice melt rates. Conversely, lower Pt/C mass ratios, lower ionomer contents, and larger carbon sphere radius are observed to delay the melting process. It is suggested that a balanced approach to Pt/C mass ratio, ionomer content, and carbon sphere radius is considered in the design of the catalyst layer to optimize cold start performance and thermal management efficiency of fuel cells. This study delves deeply into the key factors of fuel cell cold start and provides theoretical support for its performance optimization.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"404 ","pages":"Article 136331"},"PeriodicalIF":6.7,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144703395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influences of graphite on the fusibility and phosphorus release characteristics of phosphorus-rich biomass ash under different atmospheres","authors":"Hao Wu ,&nbsp;Jinzhe Li ,&nbsp;Xia Liu ,&nbsp;Chaoyue Zhao ,&nbsp;Xudong Song ,&nbsp;Qinghua Guo ,&nbsp;Xueli Chen ,&nbsp;Jin Bai ,&nbsp;Guangsuo Yu","doi":"10.1016/j.fuel.2025.136346","DOIUrl":"10.1016/j.fuel.2025.136346","url":null,"abstract":"<div><div>In gasification applications of phosphorus-rich biomass, phosphates in the feedstock may be reduced by the residual carbon and thus alter the melting behavior of the ash and lead to phosphorus release into the gas phase. In this study, the fusion characteristic temperatures of two phosphorus-rich biomass ashes mixed with 0–10 wt% graphite were determined under argon (Ar) or carbon dioxide (CO₂), respectively. Results showed that the ash fusion temperatures (AFTs) of sludge ash decreased and then increased with the increase of graphite content under Ar atmosphere, while it increased and then decreased under CO₂ atmosphere. AFTs of distillers’ grains ash increased due to the graphite addition in both atmospheres, and the increase was more.</div><div>significant under Ar atmosphere. The presence of CO₂ in the atmosphere changed the magnitude of the variation in AFTs caused by graphite. According to XRD analysis, equilibrium calculations and reaction thermodynamic parameters, metallic iron, free SiO₂ and Al₂O₃ facilitated the lowering of the thermodynamic temperature threshold for the carbothermic reaction of calcium-bearing phosphates. The iron phosphide compounds, which formed after the capture of phosphorus by metallic iron, had good thermal stability and prevented the release of phosphorus from the ash slag into the gas phase. Under CO₂ atmosphere, the carbothermic reaction of phosphates was limited by the preferential reaction between graphite and CO₂. Measurements of the phosphorus content in the 1400°C quenched slag obtained by digestion and ICP-OES indicated that a graphite content of 5 <em>wt</em>% or more in the ash along with a low iron oxide content, a low CO₂ concentration in the atmosphere, and the attainment of a temperature threshold for the carbothermic reaction are necessary conditions for the release of phosphorus to the gas phase under gasification conditions.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"404 ","pages":"Article 136346"},"PeriodicalIF":6.7,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144703428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of asphaltenes and molecular composition on the adsorption mechanisms of surfactant mixtures onto basal sandstone of the carbonera formation","authors":"Victoria Eugenia Mousalli Diaz ,&nbsp;Ana María Lozada ,&nbsp;Margy Daniela Salazar ,&nbsp;Ronald Mercado","doi":"10.1016/j.fuel.2025.136297","DOIUrl":"10.1016/j.fuel.2025.136297","url":null,"abstract":"<div><div>The adsorption of surfactants from aqueous solutions in porous media is a determining parameter in enhanced oil recovery processes. Surfactant loss due to adsorption on the reservoir rocks is associated to an efficiency decrease during traditional chemical flooding, as it diminishes the reduction of oil–water interfacial tension. However, in the case of oilfields stimulations by cyclic injections of surfactant formulations, adsorption can lead to surface wettability changes. Natural crude-oil polar molecules, such as asphaltenes adsorbed on the mineral are associated to oil-wet surfaces. In such cases, surfactants molecules can compete with asphaltenes for adsorption onto the porous medium or being adsorbed onto these molecules by hydrophobic interactions. Traditional studies focus on the static adsorption isotherms of solid/surfactants systems. This study investigates the adsorption behavior of anionic/nonionic surfactant mixtures including asphaltenes molecules, focusing on the influence of molecular composition and critical micelle concentration. Three surfactant formulations were evaluated: two highly hydrophilic formulations, each composed of two molecules with significantly different water affinities, and one formulation with reduced hydrophilicity. Adsorption mechanisms were analyzed across concentration ranges, with particular attention to monomeric and micellar regions. Results revealed that adsorption behavior is governed by the surfactants’ hydrophilicity and interactions with the substrate or asphaltenes. In the hydrophilic Formulation 1, asphaltenes had minimal impact on total adsorption, but selective adsorption of anionic surfactants on asphaltenes was observed. In contrast, the less hydrophilic Formulation 2 exhibited reduced adsorption in the presence of asphaltenes, with enhanced interfacial excess below the critical micelle concentration attributed to electrostatic and hydrophobic interactions. Finally, the hydrophilic Formulation 3 showed significantly increased adsorption in the presence of asphaltenes due to the reduced water affinity of its components. These findings suggest that formulations with balanced hydrophilicity and molecular interactions can enhance adsorption stability and maintain interfacial tension, providing valuable insights for optimizing surfactant performance in enhanced oil recovery applications.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"404 ","pages":"Article 136297"},"PeriodicalIF":6.7,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144695377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evolution of learning curve and white box machine learning models for estimating in-situ stresses based on velocity-stress relationship","authors":"Ayyaz Mustafa ,&nbsp;Guanyi Lu ,&nbsp;Andrew P. Bunger","doi":"10.1016/j.fuel.2025.136306","DOIUrl":"10.1016/j.fuel.2025.136306","url":null,"abstract":"<div><div>Reliable estimation of in-situ stresses has recently been demonstrated using an integrated deep learning/machine learning (DL/ML)-based workflow requiring training and validation using laboratory-based true triaxial ultrasonic velocity (TUV) experimental data representing ultrasonic velocities at various stress combinations. However, it remains to clarify how many TUV experiments must be performed in order to effectively and efficiently train the model. This paper presents analysis of the learning curve of the model for different dataset sizes, thereby defining the smallest effective training dataset to develop reliable prediction models. The ML/DL models were developed using TUV data obtained using five different subsurface core samples from the Utah FORGE well 16B(78)–32. Velocities were measured for 93 stress combinations per sample. Initially, prediction performances of ML/DL models were compared using 20, 40, 60, 80 and 100 percent of the total dataset. Learning curve analysis demonstrated the improvement in prediction performance up to 80% of the dataset, indicating that a model with similar predictive capacity could have been developed with 20% fewer data points collected in the laboratory. Introducing a learning curve analysis early in a project can therefore lead to significant cost savings when applying a DL/ML approach to in-situ stress estimate based on velocity-stress relationships.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"404 ","pages":"Article 136306"},"PeriodicalIF":6.7,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144695379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative assessment of residual carbon content and oxidative shrinkage behavior of coal gasification slag through in situ high-temperature stage microscope","authors":"Bin Xue ,&nbsp;Qian Zhang ,&nbsp;Le Li ,&nbsp;Baolin Zhang ,&nbsp;Xiangyang Li ,&nbsp;Peng Zhi ,&nbsp;Yujing Yang ,&nbsp;Wei Huang","doi":"10.1016/j.fuel.2025.136358","DOIUrl":"10.1016/j.fuel.2025.136358","url":null,"abstract":"<div><div>Separation of residual carbon from inorganic components has been recognized as an essential strategy for the high-value utilization of coal gasification slag (CGS), while limited studies were conducted to directly examine the distribution of the residual carbon in CGS. In this study, CGS was pretreated by being wet-sieved, acid-washed or ashed, and the shrinkage behavior of the above samples during the oxidation process were studied through in situ high-temperature stage microscope. The results indicated that the carbon-containing CGS predominantly exhibited a carbon framework and fine-sized ash particles were wrapped or nested within the pores of carbon particles. The shrinkage of the samples within the temperature range of 550–650 °C was mainly associated with the oxidation of the residual carbon. Therefore, the residual carbon content in CGS could be quantitatively assessed according to the shrinkage behavior. A nonlinear correlation between the shrinkage rate of CGS and the residual carbon content across the full particle size range was established and the reliability of the derived fitting formula was validated. In addition, the shrinkage of CGS within the temperature range of 750–900 °C was associated with the bonding interactions between residual C=O and O=C-O functional groups and metallic bonds. This research can evaluate the separability by directly investigating the distribution of residual carbon in CGS, which provides important guidance for the effective separation of carbon and ash in CGS.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"404 ","pages":"Article 136358"},"PeriodicalIF":6.7,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144694283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of hydrogen enrichment on flame stability, thermoacoustic oscillations, and combustion characteristics in premixed propane swirl flames: An experimental study","authors":"Ahmed Gaber H. Saif ,&nbsp;Md. Imteaz Ahmed ,&nbsp;Qazi Talal ,&nbsp;Esmail M.A. Mokheimer","doi":"10.1016/j.fuel.2025.136373","DOIUrl":"10.1016/j.fuel.2025.136373","url":null,"abstract":"<div><div>This paper depicts the results and analysis of experimental investigations on the effect of hydrogen enrichment on the combustion characteristics of premixed C₃H₈/air flames in a Dual Annular Counter Rotating Swirl (DACRS) combustor. The novelty of the burner, developed for this experimental study, lies in its ability to independently regulate swirl and jet flows in concentric annuli. This design enables operation in multiple modes: swirl, jet, partially swirling, or stratified, thus effectively mimicking practical gas turbine conditions. In this work, the burner was operated under fully premixed swirl conditions. Hydrogen enrichment (0–50 % by volume) and global equivalence ratios (from blowout limits up to 1.0) were systematically evaluated. The primary objectives were to quantify the effects of hydrogen addition on flame stability, thermoacoustic dynamics, temperature distributions, and emissions performance. Experimental results demonstrated that hydrogen enrichment significantly extends lean blowout limits up to 21 %. This improvement is attributed to increased flame speed, diffusivity, and OH radical production. Thermoacoustic analysis, utilizing Fast Fourier Transform (FFT) and Phase Space Reconstruction (PSR), revealed a clear transition from stable to unstable combustion regimes with increasing hydrogen content. This instability was characterized by enhanced pressure-heat release coupling and limit-cycle oscillations. Temperature profiles exhibited limited sensitivity to hydrogen fraction, showing stronger dependence on equivalence ratio. Emission analysis revealed substantial reductions in CO₂ (10.5 %) and CO (33.3 %). However, these benefits were accompanied by a moderate increase (21 %) in NOx emissions. This increase in NOx is attributed to elevated flame temperatures and radical formation. Overall, these findings highlight hydrogen’s potential to improve flame stability and combustion efficiency. They provide critical experimental benchmarks for modeling and advancing low-emission, hydrogen-enriched combustion technologies.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"404 ","pages":"Article 136373"},"PeriodicalIF":6.7,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144694282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Oxidation-assisted pyrolysis characteristics and feasibility of the autothermic pyrolysis in-situ conversion process of low-medium maturity organic-rich shale","authors":"Lihong Yang ,&nbsp;Dongxue Yu ,&nbsp;Hao Zeng ,&nbsp;Jianzheng Su ,&nbsp;Wei Guo ,&nbsp;Dandi Zhao ,&nbsp;Sunhua Deng ,&nbsp;Youhong Sun","doi":"10.1016/j.fuel.2025.136368","DOIUrl":"10.1016/j.fuel.2025.136368","url":null,"abstract":"<div><div>Despite being a substantial unconventional hydrocarbon resource with vast global reserves, low-medium maturity organic-rich shale (OS) is still difficult to effectively exploit with traditional methods. This research focuses on the unique characteristics of low-medium maturity OS, particularly its high free bitumen content, and suggests an auto-thermal in-situ conversion (ATS) method activated by direct hot air injection. The OS samples were made by hydrothermal treatment of high-total organic carbon (TOC) oil shale. The behavior of its oxidative pyrolysis in air environment and product evolution characteristics were systematically investigated using thermogravimetric-differential scanning calorimetry (TG-DSC) and low-temperature pyrolysis experiments. The study also explored the triggering mechanism of free bitumen oxidation at low temperatures, the energy balance between semi-coke combustion exothermicity and raw rock pyrolysis endothermicity, and the strategy for selecting process parameters. TG analysis revealed that free bitumen substantially reduces the oxidation onset temperature to 220 °C (compared to 390 °C under N₂), facilitating low-temperature reaction initiation. The heat released from the oxidation process was able to induce the kerogen to enter a state of intense cracking 43 °C earlier. Pyrolysis tests showed that hydrocarbons were first produced at 280 °C, the yield rose at 340 °C, and that kerogen cracking occurred quickly at 430 °C. Energy balance analysis verified that semi-coke combustion generates enough heat to start and maintain auto-thermal pyrolysis. An ideal self-sustaining chain reaction is achieved at a cracking zone temperature of 460 °C and an energy utilization efficiency of more than 75%. This study provides novel insights into cost-effective in-situ conversion of low-medium maturity OS and as well as critical technical guidelines for industrial-scale development.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"404 ","pages":"Article 136368"},"PeriodicalIF":6.7,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144695382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}