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        <title>Frontiers in Fuels | New and Recent Articles</title>
        <link>https://www.frontiersin.org/journals/fuels</link>
        <description>RSS Feed for Frontiers in Fuels | New and Recent Articles</description>
        <language>en-us</language>
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        <pubDate>2026-04-06T17:28:59.223+00:00</pubDate>
        <ttl>60</ttl>
        <item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2026.1748966</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2026.1748966</link>
        <title><![CDATA[The role of combustion (and fuels) in a decarbonizing world]]></title>
        <pubdate>2026-03-02T00:00:00Z</pubdate>
        <category>Review</category>
        <author>Jörg Leicher</author><author>Anne Giese</author><author>Christoph Wieland</author>
        <description><![CDATA[Access to energy is essential for the modern world, yet at the same time, anthropogenic greenhouse gas emissions are caused by energy-related activities across all sectors due to the predominance of fossil fuels. Today, most of the primary energy is still being provided by fossil fuels, with combustion being a key technology. In order to combat climate change, energy has to be decoupled from greenhouse gas emissions, with electricity and electrification being important pathways towards a net-zero energy system. However, electricity also has drawbacks as an energy carrier, especially in the context of large-scale energy storage, but also for applications requiring high energy densities. This, in addition to providing dispatchable power generation capacities for grid balancing and covering longer periods of reduced renewable power generation, is expected to result in significant contributions of synthetic and biogenic fuels to the energy landscape. The main purpose of combustion-based technologies will change from providing most of the primary energy to the energy system to complementing variable renewable energies when and where needed. This change of purpose has consequences for the directions of combustion research and development: while traditional topics such as equipment efficiency and pollutant emissions such as NOX will still be important, other topics such as more flexible and dynamic operation modes, hybrid applications and system integration will play a much bigger role in the future, along with the use of new fuels such as hydrogen or ammonia.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2025.1670642</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2025.1670642</link>
        <title><![CDATA[Brown algae-functionalized clays as a novel biosupports for lead-free bismuth halide perovskites in the CO2 reduction]]></title>
        <pubdate>2026-01-16T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Emireth A. Mellado-Lira</author><author>Edith Luévano-Hipólito</author><author>Luis F. Garay-Rodríguez</author><author>Leticia M. Torres-Martínez</author>
        <description><![CDATA[IntroductionOne of the main environmental problems is air pollution due to high CO2 emissions, a greenhouse gas that contributes to climate change because of the excessive use of fossil fuels. For this reason, CO2 reduction emerges as a promising solution by converting it into renewable fuels using sunlight and advanced semiconductor materials. Recently, hybrid systems based on artificial leaves composed of lead-free halide perovskites and porous support materials have been demonstrated to be highly efficient for CO2 reduction. In addition, the recycling and utilization of natural sources such as the brown algae, considered a plague in the Caribbean, represents an additional advantage for the pollution reduction, carbon sequestration, and social and economic impacts.MethodsThis research proposes an innovative solution to address this environmental problem by demonstrating that hybrid systems based on bismuth halide perovskites (K3Bi2I9) and brown algae-functionalized clay biosupports are promising for the reduction of CO2 with high efficiencies for formic acid production (2.5 mmol h-1) under visible light. The content of the brown algae was investigated to find the best load that promotes higher and stable CO2 reduction efficiencies.ResultsThe presence of the brown algae enhanced light absorption by its chlorophyll, provided free electrons to the semiconductor and highly reactive species (•OH), that favored the formation of C1-C3 products, e.g., HCOOH, CH3COOH, and CH3(CH2)2OH, with efficiencies in the order of >1 mmol. In addition, the stability of the hybrid systems was demonstrated after five hours of continuous visible light irradiation in liquid phase, which analysis of the medium showed a minimal leaching of potassium.DiscussionThe addition of 5 wt.% brown algae in the clays promoted both high efficiency and stability of the hybrid system by preventing cracking, while promoting a porous framework that maintained effective CO2 adsorption. This enhanced effect was attributed to efficient perovskite encapsulation and the presence of chlorophyll (from algae) acting as an electron donor, enhancing light absorption and charge transfer. This synergistic effect enabled efficient CO2 conversions to C1–C3 value-added products. In conclusion, this work demonstrated that the utilization of abundant natural materials such as clays and sargassum supports an ecological and scalable approach while addressing global and local environmental problems.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2025.1716359</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2025.1716359</link>
        <title><![CDATA[Tailored porosity from waste biomass: mesoporous bio-adsorbents for targeted treatment of complex industrial wastewaters]]></title>
        <pubdate>2026-01-14T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Saqib Sohail Toor</author><author>Kamaldeep Sharma</author><author>Rebekka Klemmt</author><author>Mohammad Aref Hasen Mamakhel</author><author>Abdenour Achour</author>
        <description><![CDATA[The valorization of waste biomass into tailored adsorbents presents a sustainable strategy for combating industrial water pollution. This study highlights the critical role of precursor morphology in determining the textural properties and function of bio-adsorbents derived from wheat straw (WS) and the organic fraction of municipal solid waste known as biopulp (BP). Through carbonization and KOH activation, the fibrous WS was transformed into a microporous, high-surface-area activated wheat straw (AWS) bio-adsorbent, while the compact BP yielded a mesoporous network in activated biopulp (ABP). This structural difference affects adsorption performance: AWS demonstrated superior efficacy in batch removal of phenols (93.2%) and total organic carbon (85%) from the complex hydrothermal liquefaction aqueous phase (HTL-AP), whereas ABP excelled in treating produced water (PW), achieving >95% removal of organic pollutants. Continuous fixed-bed column studies confirmed the scalability of AWS for HTL-AP treatment, revealing distinct breakthrough dynamics between bulk parameters and specific contaminants. This work provides evidence supporting precursor-dependent tailoring of pore structure for targeted wastewater treatment, providing a possibility for a circular and sustainable solution for the treatment of complex industrial wastewaters.]]></description>
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        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2025.1722932</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2025.1722932</link>
        <title><![CDATA[Composition-centered prediction of kenaf core saccharification for next-generation bioethanol via machine learning]]></title>
        <pubdate>2025-11-21T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Yitong Niu</author><author>Ying Ying Tye</author><author>Chee Keong Lee</author><author>Mardiana Idayu Ahmad</author><author>Cheu Peng Leh</author>
        <description><![CDATA[IntroductionBiomass pretreatment outcomes are heterogeneous across routes and severities, and condition-centered empirical models often fail to generalize beyond the settings on which they were trained, limiting early-stage decisions about where to focus costly wet-lab effort. This study evaluates a composition-centered surrogate that treats the post-pretreatment solid composition—cellulose, hemicellulose, lignin—as the input space and predicts enzymatic glucose yield as the response for kenaf core.MethodsKenaf core solids subjected to water, dilute-acid, and alkaline pretreatments were characterized for post-pretreatment cellulose, hemicellulose, and lignin contents and hydrolyzed under a fixed enzymatic protocol to obtain glucose yield at 24 h. The curated dataset (n = 35) was used to train Random-Forest regressors tuned by six hyperparameter optimizers (grid search, random search, Bayesian optimization, genetic algorithm, particle swarm optimization, and simulated annealing). Generalization performance was assessed using nested cross-validation and a held-out test split, with feature contributions examined via permutation importance and accumulated local effects.ResultsAcross optimizers, held-out performance clustered tightly (test R2 ≈ 0.49–0.55; RMSE 4.42–4.69 GY%), indicating that attainable accuracy is governed more by model capacity and data coverage than by optimizer choice. Feature diagnostics converged on a cellulose-led mechanism, with cellulose showing a positive monotonic effect on yield, lignin a negative effect, and hemicellulose a weaker, context-dependent influence. Iso-yield maps in the cellulose–lignin plane delineated feasible composition windows that prioritize high-cellulose/low-lignin regions under different hemicellulose levels.DiscussionWithin this accuracy band, the composition-centered surrogate is best suited for uncertainty-aware screening to prune unproductive regions of composition space before targeted design-of-experiments, rather than replacing detailed process optimization. The workflow provides a transferable template for small-sample, composition-based modeling of lignocellulosic feedstocks and can be extended to other varieties and integrated with mechanistic descriptors as data accumulate.]]></description>
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        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2025.1674030</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2025.1674030</link>
        <title><![CDATA[Italy’s biomethane investment under the national recovery and resilience plan: a flagship initiative for Europe’s sustainable fuel transition]]></title>
        <pubdate>2025-10-15T00:00:00Z</pubdate>
        <category>Opinion</category>
        <author>Giorgio Centurelli</author>
        <description></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2025.1643675</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2025.1643675</link>
        <title><![CDATA[Microalgae: Promising solutions paving the way toward a greener and more sustainable future]]></title>
        <pubdate>2025-08-18T00:00:00Z</pubdate>
        <category>Mini Review</category>
        <author>Yunhan Qin</author><author>Tingfu Li</author><author>Changliang Nie</author><author>Xueyun Geng</author><author>Xiaomin Sun</author>
        <description><![CDATA[Microalgae represent a promising solution for achieving greener and more sustainable applications, owing to their rapid growth rates, high photosynthetic efficiency, and capacity to produce valuable compounds such as lipids. Biofuels based on microalgae have emerged as a promising alternative to fossil fuels due to their sustainable and renewable nature. Moreover, the use of microalgae cultivated in wastewater not only contributes to biofuel production but also provides additional benefits such as wastewater treatment and CO2 sequestration to realize the carbon neutrality. However, the commercial viability of microalgae-based biofuels remains uncertain. This article reviews advancements in microalgae-based sustainable production while exploring its multi-objective applications beyond energy generation. Multi-objective applications, including multi-algal systems, species development, process optimization, and dust suppressant are necessary to improve cost-effectiveness and enhance overall feasibility.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2025.1528451</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2025.1528451</link>
        <title><![CDATA[Achieving biodiesel standards through saturation level optimisation]]></title>
        <pubdate>2025-03-04T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Kemal Masera</author><author>Abul Kalam Hossain</author><author>Gareth Griffiths</author>
        <description><![CDATA[Biodiesels made from waste feedstock are viable sustainable fuels for compression-ignition engine use. However, biodiesels produced from single waste sources do not always comply with the European biodiesel standard. This study investigates fuel quality and engine performance when two biodiesels with different characteristics are blended at various proportions. Waste cooking oil biodiesel was blended with sheep fat biodiesel, which has a lower unsaturated fatty acid content. The engine performance, combustion, and exhaust emission characteristics of the neat biodiesels and their blends (at 60/40, 50/50, and 30/70 ratios) were analysed. The results showed that 60/40 and 50/50 blends met the core parameters of the BS EN 14214 biodiesel standard and improved combustion and emission characteristics compared to neat biodiesels and diesel. The 50/50 blends gave up to 5% and 14% improvements in the in-cylinder pressure and maximum heat release rate, respectively, compared to the same results for neat biodiesel operation. Reduction of up to 73% in CO, 96% in smoke and 3% in CO2 emissions was observed. However, NOx emission was 2.5% higher than diesel. The results reveal that carefully selected biodiesel–biodiesel blending could meet fuel standards, improve engine performance, and reduce exhaust emissions.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2025.1464944</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2025.1464944</link>
        <title><![CDATA[A geographic information systems selection approach to repurposing offshore oil & gas assets for green hydrogen production]]></title>
        <pubdate>2025-02-24T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>William Rupp</author><author>Karim Rabea</author><author>Ruoyang Yuan</author>
        <description><![CDATA[Integrating green hydrogen production with existing oil and gas infrastructure is seen as viable step for the reutilization of oil and gas assets. Green hydrogen production through offshore wind has the potential to extend the lives of these systems, reduce decommissioning costs and provide a source of clean energy. This paper presents an outlook on wind license areas using existing oil and gas infrastructure. Three scenarios are proposed for the conversion of offshore assets into wind turbine sites, including the conversion of a platform into a substation. A methodology is provided to assess the suitability of offshore wind using exclusion criteria and the cessation of production dates for oil and gas infrastructure. This methodology is applied to the UK Exclusive Economic Zone (EEZ), and the results show that 7.4% of the UK EEZ is within the top suitability index for wind turbine development. The cost of green hydrogen production from different offshore locations is estimated to be in the range of 9.78–11.76 £/kgH2 depending on the wind farm scale and the distance. The study highlights the potential for using existing infrastructure for wind turbine development and provides valuable insights for stakeholders in the energy industry.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2024.1404367</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2024.1404367</link>
        <title><![CDATA[Methane emission reduction through hydrogen blending in a large bore 2-stroke lean-burn natural gas compressor engine]]></title>
        <pubdate>2024-12-09T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Greg Vieira</author><author>Rachel Lorenzen</author><author>Mark Patterson</author><author>Daniel Olsen</author>
        <description><![CDATA[Impending and increasingly stringent emissions regulations regarding natural gas compressor engines drive the research behind blending hydrogen with natural gas to make these internal combustion engines and their combustion process more efficient. This investigation seeks to answer two fundamental questions: will blending hydrogen with natural gas reduce overall engine fuel consumption, and can greenhouse gas emissions be reduced by blending hydrogen with natural gas? A 4-cylinder Cooper–Bessemer GMV engine, housed at Colorado State University’s Powerhouse facility, was investigated for hydrogen–natural gas blending using multiple engine configurations. A lean-burn engine uses an active pre-combustion chamber as its ignition source, along with electronically activated high pressure fuel injection in the main combustion chamber. One configuration tested utilized high-pressure fuel injection and blending in hydrogen, up to 40% by volume, in both the main chamber and pre-combustion chamber fuel supplies. A second configuration, where the main combustion chamber fuel was solely natural gas and only the pre-combustion chamber received hydrogen-blended natural gas, was also tested. The final configuration to be tested used low pressure fuel injection with mechanically actuated valves in the main chamber with a traditional spark plug ignition source. All engine configurations saw reductions in methane emissions of up to 30% using blended natural gas and hydrogen. Carbon dioxide emissions were also shown to be reduced for the two configurations. A reduction in brake-specific fuel consumption of up to 2% was also seen for two configurations. These results support the hypothesis that blending hydrogen into natural gas can reduce engine total fuel consumption and reduce greenhouse gas emissions.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2024.1401691</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2024.1401691</link>
        <title><![CDATA[A quantitative study of OH and NO concentration of a premixed laminar kerosene flame using a flat-flame burner at atmospheric pressure]]></title>
        <pubdate>2024-11-18T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Si Shi</author><author>Kevin J. Hughes</author><author>Mohamed Pourkashanian</author>
        <description><![CDATA[In the context of global warming and the increasing demands for the application of sustainable fuels, measurements of a variety of experimental targets under a wide range of conditions are crucial to improving the fundamental understanding of real jet fuels and developing quality kinetic mechanisms for large hydrocarbons. Planar laser-induced fluorescence (PLIF) is an effective approach to investigate concentrations of important species of a given flame while quantifying the fluorescence image remains a great challenge with significant uncertainties. This investigation aims to improve the fundamental understanding of the oxidation of kerosene-based mixtures at two equivalence ratio conditions. Two gas fuels are utilized as the reference for the quantitative studies. For each flame condition, relative OH and NO quantities and temperature profiles were measured by applying the PLIF and coated fine wire type R Pt/Pt-Rh thermocouples, respectively. The converted OH and NO results were subsequently compared with the simulation by using ANSYS Chemkin Pro, and the results indicate that reliable temperature profiles are the key to accurately quantify the species concentration of a given flame.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2024.1416716</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2024.1416716</link>
        <title><![CDATA[Hydrogen-natural gas fuel blending in a “rich burn” engine with 3-way catalyst]]></title>
        <pubdate>2024-09-13T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Nicholas Katsampes</author><author>David Montgomery</author><author>Gregg Arney</author><author>Daniel B. Olsen</author>
        <description><![CDATA[Interest in hydrogen (H2) fuels is growing, with industry planning to produce it with stranded or excess energy from renewable sources in the future. Natural gas (NG) utility companies are now taking action to blend H2 into their preexisting pipelines to reduce greenhouse gas (GHG) emissions from burning NG. Stoichiometric (“rich burn”) NG engines that operate on pipeline NG and will receive blended fuel as more gas utilities expand H2 production. These engines are typically chosen for their low emissions owing to the 3-way catalyst control, so the focus of this paper is on the change in emissions like carbon monoxide (CO) and nitrogen oxides (NOx) as the fuel is blended with up to 30% H2 by volume. The Caterpillar CG137-8 natural gas engine used for testing was originally designed for industrial gas compression applications and is a good representative for most “rich burn” engines used across industry for applications such as power generation, gas compression, and water pumping. A significant greenhouse gas (GHG) emissions reduction is observed as more H2 is added to the fuel. Increasing H2 in the fuel changes combustion behavior in the cylinder, resulting in faster ignition and higher cylinder pressures, which increase engine-out NOx emissions. Post-catalyst CO and NOx both decrease slightly with increasing H2 while operating at the optimal “air-fuel” equivalence ratio (λ). A “rich burn” engine with 3-way catalyst can tolerate up to 30% H2 (by vol.) while still meeting NOx and CO emissions limits. However, at elevated levels of H2, increased engine-out NOx emissions narrow the λ range of operation. As H2 is added to NG pipelines, some “rich burn” engine systems may require larger catalysts or more precise λ control to accommodate the increased NOx production associated with a H2-NG blend. Sudden step-increases in H2 cause dramatic changes in λ, resulting in large emissions of post-catalyst NOx during the transition. Comparable changes in H2 at elevated concentrations cause larger spikes in NOx than at lower concentrations. Better tuned engine controllers respond more quickly and produce less NOx during H2 step-transitions.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2024.1404052</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2024.1404052</link>
        <title><![CDATA[A technology integration approach for optimising biohydrogen production from food waste]]></title>
        <pubdate>2024-08-21T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Cynthia Kusin Okoro-Shekwaga</author><author>Mark Wilmshurst</author>
        <description><![CDATA[Dark fermentation of food waste for biohydrogen production is a progressive technology that can contribute to low-cost solutions to the global clean energy need. As dark fermentation research progresses, it is important to evaluate opportunities for real-life application such as integration into existing anaerobic digestion systems. The present study proposes a novel approach of combined inoculum and food waste heat shock pretreatment for biohydrogen production through dark fermentation. It evaluates the effect of the heating duration (at 115°C) and starting pH on the biohydrogen yield and system profiles in two stages, namely, Exp1 and Exp2. Exp1 investigated the optimal heating duration and starting pH for a combined inoculum/food waste heat shock pretreatment. A 24-h biohydrogen production test at four heating durations (15, 30, 45 and 60 min) was assayed at acidic and alkaline pH ranges (4, 5, 6 and 8, 9, 10). The optimal starting pH from these experiments across all four heating durations was pH 5. Biohydrogen yield increased linearly from 37.4 to 63.8 mL/gVS, with an increase in heating duration from 15 to 60 min at pH 5. However, an optimal heating duration was not reached, therefore, additional tests were conducted at pH 5 for extended heating durations of 75–120 min. Biohydrogen yield was similar at 75, 90 and 105-min heating durations in a range of 69.7–73.5 mL/gVS. Above 105 min of heating duration, the overall gas production starts to decline, making it the maximum allowable heating duration. In Exp2, a comparative analysis of the system profiles between the combined inoculum/food waste pretreatment (Test) and inoculum-only pretreatment (Control) was investigated using the optimal heating duration range (75 and 105 min) and starting pH of 5. The peak biohydrogen yield from the Control was achieved following a 75-min heating duration (84.5 mL/gVS, 58.6%), while this was achieved following a 90-min heating duration for the Test (81.3 mL/gVS, 53.3%). Higher volatile fatty acids fermentation and pH recovery were achieved in the Test in addition to potential economic savings compared to the Control. Therefore, the innovative approach of combined food waste/inoculum heat shock pretreatment (Test) presents opportunities to integrate dark fermentation into existing anaerobic digestion systems as a step to scale up the dark fermentation technology from lab to real-life application.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2024.1397962</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2024.1397962</link>
        <title><![CDATA[Review of technological developments and LCA applications on biobased SAF conversion processes]]></title>
        <pubdate>2024-07-12T00:00:00Z</pubdate>
        <category>Review</category>
        <author>Eleanor Borrill</author><author>S. C. Lenny Koh</author><author>Ruoyang Yuan</author>
        <description><![CDATA[The aviation industry, driven by evolving societal needs, faces rising demand post-Covid and increasing pressure to align with emission reduction targets, prompting the development of drop-in sustainable aviation fuels (SAF). Their compatibility with existing aircraft and infrastructure will help to implement these fuels with the urgency the global climate crisis requires. This review delves into the benefits and challenges of various feedstocks, addressing complexities in estimating feedstock availability by location. Identified research gaps include enhancing feedstock availability, yield, and diversity, investigating compositions, and implementing sustainable agricultural practices. A summary of ASTM-certified conversion processes and technical specifications is outlined, prompting further research into conversion efficiency, catalyst selectivity, blending limits, aromatic compounds, combustion instability, and numerical modeling. A summary of recent life cycle assessments (LCA) highlighted gaps in cradle-to-cradle assessments, location-specific analyses, temporal considerations, and broader environmental impact categories. Recommendations stress obtaining primary data for enhanced LCA accuracy, conducting more specialized and general LCA studies and combining LCA, techno-economic analysis, fuel requirements, and socio-political assessments in multi-criteria decision analysis. This paper underlines the pressing need for comprehensive research to inform SAF production alternatives in the context of global climate crisis mitigation.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2024.1378361</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2024.1378361</link>
        <title><![CDATA[Critical review of the role of ash content and composition in biomass pyrolysis]]></title>
        <pubdate>2024-03-08T00:00:00Z</pubdate>
        <category>Review</category>
        <author>Lokeshwar Puri</author><author>Yulin Hu</author><author>Greg Naterer</author>
        <description><![CDATA[In the face of environmental challenges (e.g., dramatically increasing greenhouse gas emissions and climate change), it is utmost of importance to sustainable energy systems. Biomass consisting of agricultural and forest waste, municipal solid waste, and aquatics, has been identified as alternative and promising fuel sources. Thermochemical conversion approaches like pyrolysis can turn various types of biomass into three valuable product streams, namely, bio-oil, biochar, and syngas. To date, past review articles have considered the major operating parameters of kinetics, chemistry, and the application of pyrolysis products. However, ash content is one of the key biomass components that lacks investigation on its influence during biomass pyrolysis with respect to products yield and properties. This review article examines: i) the ash content and composition in different types of biomass; ii) effects of ash content on catalytic pathway and biomass thermal degradation; iii) ash related problems in the thermal degradation of biomass; and iv) available deashing techniques for biomass. The review aims to provide new understandings and insights regarding the effects of ash content and composition on biomass pyrolysis.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2023.1320326</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2023.1320326</link>
        <title><![CDATA[Irreversible bonds for higher stability of COF materials in photocatalytic reactions]]></title>
        <pubdate>2024-02-05T00:00:00Z</pubdate>
        <category>Review</category>
        <author>Fang Ma</author><author>Liqun Ye</author>
        <description><![CDATA[Covalent organic frameworks (COFs), one of a multitude of advanced mainstream materials in photocatalysts, are crystalline porous materials with tunable topology and high porosity and are connected by dynamic covalent bonds. We sought to achieve efficient photocatalytic yields, making the stability of the bond energy crucial. Stable bond energy will enable our products to be more economically efficient. At present, the main photocatalysts are reversible imine bonds and other 2D COFs, but irreversibly stable COFs are seldom involved. Therefore, this review surveys the relevant literature to explore the stability of irreversible bond energy, elaborating the synthesis schemes of irreversible bonds. Irreversibly connected bonds will improve the stability and durability of our synthesized catalyst in practical applications, so we seek to explore the stability of bond energy for our practical applications. In this review, we offer a detailed summary of the irreversible bonding pattern, explore the stability of COFs, and summarize classic highly crystalline ordered semiconductor COFs with irreversible bonding methods.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2023.1296502</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2023.1296502</link>
        <title><![CDATA[Feasibility on equivalence ratio measurement via OH*, CH*, and C2* chemiluminescence and study of soot emissions in co-flow non-premixed DME/C1–C2 hydrocarbon flames]]></title>
        <pubdate>2024-01-08T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Abdallah Abu Saleh</author><author>Kevin J. Hughes</author><author>Graham Hargrave</author><author>Ruoyang Yuan</author>
        <description><![CDATA[The effects of dimethyl ether (DME) addition to methane and ethylene fuels on the combustion characteristics of heat release, soot emissions, and flame temperature were investigated experimentally and numerically in a non-premixed laminar flame configuration. The flame-heat release soot-volume fraction was measured experimentally using CH*, OH*, and C2* chemiluminescence and planar two-color soot pyrometry, respectively. The CH*, OH*, and C2* were used to locate flame-heat release regions as well as to investigate the soot signal’s effect on their measurements. The ratios of the chemiluminescence pairs (OH*/CH* and OH*/C2*) were studied for the feasibility of map local equivalence ratios. Numerical calculations across a full range of DME mixing ratios were performed through 1D laminar flame simulations implemented with a detailed mechanism to provide an indication of the flame structures and profiles of key species including OH*, OH, CH*, CH, CH3, C3H3, C2H2, heat release rate (HRR), and flame temperature. An existing developed soot model was used in a 2D computational study to investigate its validity for modeling soot for DME (oxygenated fuel)/C2H4/N2 flames. Parametric studies have been carried out on some key parameters in the soot model to find optimum values that can be used in future studies. Although soot radiation intensities increased at a small amount (25%vol) of DME addition in the DME/methane flames, the soot pyrometry results showed a reduced soot volume fraction with an increased DME mixture ratio in both DME/methane and DME/ethylene flames studied, agreeing with the key conclusion of 1D numerical results. The flame HRR decreases with the increasing addition of DME to methane and ethylene flames and correlates with the trend of OH* and CH* profiles. The 1D simulation showed a non-monotonic correlation between OH*/CH* ratios and equivalence ratios, implying a limited use of OH*/CH* for the equivalence ratio measurement in non-premixed flames with DME additions.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2023.1303890</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2023.1303890</link>
        <title><![CDATA[Monitoring the reduction of UO3 thin film by hydrogen atoms using valence-level spectroscopy: correlating the U5f1 signal to surface hydroxyls]]></title>
        <pubdate>2023-12-08T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>G. El Jamal</author><author>T. Gouder</author><author>R. Eloirdi</author><author>M. Jonsson</author><author>H. Idriss</author>
        <description><![CDATA[The reaction of a UO3 thin film with atomic hydrogen was studied by He(II) ultraviolet photoelectron spectroscopy (UPS) in the temperature range 190–300 K. UO3 reduction was instantaneously observed once it contacted H atoms at 10–7 torr. The reduction was manifested by the presence of U5f1 electrons in He(II) UPS at approximately 1.5 eV below the Fermi level. Based on the peak characteristics, the valence band shape (composed largely of O2p orbitals in addition to some contribution from U6d and U5f orbitals), and X-ray photoelectron spectroscopy (XPS) U4f lines, the reduction of U6+ in UO3 only results in the formation of U5+ cations and was largely limited to those on the surface. Associated with the reduction was the formation of surface hydroxyls (-OH species) due to the transfer of a proton of the H atom (H.) to surface oxygen ions, while the electron of H. is transferred to a U5f orbital. The pseudo-first-order rate constant of the initial rate of reduction at 10–7 torr and 190 K was found to be approximately 0.01 s–1. Qualitative analysis of the valence band before and after reduction indicates that O2p hybridization with U6d and U5f orbitals leads to well-distinguished features that are characteristic of UO3, U2O5, and UO2. These features, which were quantitatively reversed during the redox process, furthers the assessment of the stoichiometry of a given binary uranium oxide.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2023.1246950</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2023.1246950</link>
        <title><![CDATA[Quantitation of olefins in sustainable aviation fuel intermediates using principal component analysis coupled with vacuum ultraviolet spectroscopy]]></title>
        <pubdate>2023-12-01T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Shane Kosir</author><author>John Feldhausen</author><author>David Bell</author><author>Dylan Cronin</author><author>Randall Boehm</author><author>Joshua Heyne</author>
        <description><![CDATA[Olefins, a common intermediate from biomass conversion processes, are undesirable in jet fuel because of their poor thermal stability. This paper presents an approach for olefin quantitation using 2D gas chromatography coupled with vacuum ultraviolet spectroscopy. Principal component analysis was used to reduce the dimensionality of the spectroscopic data from a highly olefinic fuel intermediate. A principal component template was created that enabled olefin quantitation, which was compared to the existing GCxGC-VUV approach from the literature. The principal component method was able to identify and quantify trace amounts of cyclodienes, which were present at only 0.01 wt% in the fuel sample. The principal component approach also identifies species that fall outside of the GCxGC template. For instance, quantitation with the literature method resulted in an olefin concentration of 0.95 times that of the principal component method due to olefins falling outside of the expected GCxGC regions. The principal component results were compared with 13C and 1H NMR data, which confirmed that the fuel had a high concentration of olefins and alkanes with little aromatic content.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/ffuel.2023.1105637</guid>
        <link>https://www.frontiersin.org/articles/10.3389/ffuel.2023.1105637</link>
        <title><![CDATA[Advanced biorefinery feedstock from non-recyclable municipal solid waste by mechanical preprocessing]]></title>
        <pubdate>2023-02-22T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Nepu Saha</author><author>Jordan Klinger</author><author>Md Tahmid Islam</author><author>Toufiq Reza</author>
        <description><![CDATA[Because of accelerated urbanization and the development of a global economy, a large quantity of municipal solid waste (MSW) has been collected and disposed of by the municipalities. Due to this drastic increase in the disposal of MSW, the need for its management is a must to preserve the environment. Currently, approximately 50% of the total MSW generated in the United States has been utilized through various recycling, combustion, and composting technologies, which means the remaining 50% is sent to landfill; this is often known as non-recyclable MSW (nMSW). As this nMSW is physically and chemically heterogenous and contains very high amounts of inorganic material, processing is required prior to using it as a biorefinery feedstock. Thus, this study focused on how mechanical preprocessing advanced the physical and chemical properties of nMSW. The physical and chemical properties were investigated in terms of particle size distribution, bulk density, ultimate and proximate analysis, and the higher heating value (HHV). The combustion properties were examined in terms of ignition temperature, peak heat release rate, and combustion efficiency. Results showed that the variability of physical and chemical properties of nMSW can be reduced by mechanical preprocessing. For example, the variability of the bulk density of the as-received nMSW was approximately 17.3% while it reduced to 5.8% when the sample size was reduced to 2 mm. Similarly, the variability of ash and HHV reduced from 49.2% to 11.0% and 13.4%–4.2%, respectively. Combustion thermograms showed that the size reduction positively improved the combustion properties. For example, 2 mm of spec sample started to ignite approximately 4 times earlier and took 6.5 folds less time to reach the peak heating rate compared to as-received nMSW. Overall, the mechanical preprocessing reduced the variability of physical and chemical properties in addition to the improvement of combustion behavior of the nMSW which is one step forward toward the biorefinery feedstock.]]></description>
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