Pub Date : 2026-01-27DOI: 10.1016/j.fuel.2026.138528
Dylan J. Cronin, Juliano Souza dos Passos, Alan H. Zacher, Uriah Kilgore, Andrew J. Schmidt, Samuel P. Fox, Michael R. Thorson
Hydrothermal liquefaction (HTL) is an emergent technology with potential to produce transport fuels from societal wet-waste feedstocks in a more environmentally sustainable manner than the use of traditional fossil fuels. HTL converts wet wastes into biocrude using a range of different pressures (∼1400–5000 psi) and temperatures (∼275–450 °C). Much of the bench-scale research on this topic has adopted a batch approach; however, for HTL to succeed at an industrial scale, a continuous-flow (CF) reactor system is necessary. A shortcoming of the CF approach is the risk of reactor blockage during attempts to achieve plug flow, leading to significant downtime and maintenance costs. It is therefore vital to understand the fluid dynamics phenomena involved in CF-HTL so that processes and/or feedstocks can be designed to circumvent this highly detrimental outcome. The current study investigates the hydrodynamic behavior of two feed slurries (an industrial food-waste blend and a sewage-sludge blend) in a flow test system reactor designed for the purpose. The impacts of various process conditions—such as feed composition, heating profile, and flow rate—are investigated. The results provide new insights into the nature of CF-HTL reactor fouling, and the implications to subcritical CF-HTL reactor operation and design are discussed.
{"title":"Hydrodynamic behavior and design implications in continuous-flow hydrothermal liquefaction systems","authors":"Dylan J. Cronin, Juliano Souza dos Passos, Alan H. Zacher, Uriah Kilgore, Andrew J. Schmidt, Samuel P. Fox, Michael R. Thorson","doi":"10.1016/j.fuel.2026.138528","DOIUrl":"10.1016/j.fuel.2026.138528","url":null,"abstract":"<div><div>Hydrothermal liquefaction (HTL) is an emergent technology with potential to produce transport fuels from societal wet-waste feedstocks in a more environmentally sustainable manner than the use of traditional fossil fuels. HTL converts wet wastes into biocrude using a range of different pressures (∼1400–5000 psi) and temperatures (∼275–450 °C). Much of the bench-scale research on this topic has adopted a batch approach; however, for HTL to succeed at an industrial scale, a continuous-flow (CF) reactor system is necessary. A shortcoming of the CF approach is the risk of reactor blockage during attempts to achieve plug flow, leading to significant downtime and maintenance costs. It is therefore vital to understand the fluid dynamics phenomena involved in CF-HTL so that processes and/or feedstocks can be designed to circumvent this highly detrimental outcome. The current study investigates the hydrodynamic behavior of two feed slurries (an industrial food-waste blend and a sewage-sludge blend) in a flow test system reactor designed for the purpose. The impacts of various process conditions—such as feed composition, heating profile, and flow rate—are investigated. The results provide new insights into the nature of CF-HTL reactor fouling, and the implications to subcritical CF-HTL reactor operation and design are discussed.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"416 ","pages":"Article 138528"},"PeriodicalIF":7.5,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076174","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}
Pub Date : 2026-01-26DOI: 10.1016/j.fuel.2026.138512
Serhatcan Berk Akçay , Onur Güler , Temel Varol , Mehmet Fatih Kaya , Fatih Erdemir , Hüseyin Can Aksa , Mücahit Kocaman , Murat Beder , Furkan Emre Başkara
The wettability–corrosion trade-off in liquid/gas diffusion layers (LGDLs) of PEM water electrolyzers remains a persistent challenge in achieving both long-term durability and efficient electrochemical performance. In this study, titanium-based porous LGDLs with varying porosity levels were fabricated via Selective Laser Melting (SLM) and systematically investigated to resolve this design conflict. Three distinct porosity configurations (S1, S2, S3) were produced by adjusting laser parameters, resulting in increasing open porosity and decreasing wettability (contact angle increased from ∼ 60° in S1 to ∼ 118° in S3). Electrochemical testing demonstrated that the highest-porosity sample (S3) achieved the highest corrosion resistance, with a current density of only 20.18 μA·cm−2. Remarkably, despite its low wettability, S3 also exhibited the best PEM cell performance, reaching a peak current density of 29 mA.cm−2 at 2.0 V, which is more than 20 % of that of S1. This enhancement is attributed to the improved gas/liquid transport efficiency afforded by the interconnected high-porosity network, especially under pressurized flow conditions, which dominates over surface wetting effects. These results highlight that engineering porosity through SLM can simultaneously optimize corrosion resistance and electrochemical output, offering a promising pathway toward more durable and efficient LGDLs for next-generation PEM water electrolyzers in clean hydrogen production systems.
{"title":"Breaking the Wettability–Performance Trade-Off: Porosity-Tuned novel Ti Liquid/Gas diffusion layers for PEM water electrolyzers via selective laser melting","authors":"Serhatcan Berk Akçay , Onur Güler , Temel Varol , Mehmet Fatih Kaya , Fatih Erdemir , Hüseyin Can Aksa , Mücahit Kocaman , Murat Beder , Furkan Emre Başkara","doi":"10.1016/j.fuel.2026.138512","DOIUrl":"10.1016/j.fuel.2026.138512","url":null,"abstract":"<div><div>The wettability–corrosion trade-off in liquid/gas diffusion layers (LGDLs) of PEM water electrolyzers remains a persistent challenge in achieving both long-term durability and efficient electrochemical performance. In this study, titanium-based porous LGDLs with varying porosity levels were fabricated via Selective Laser Melting (SLM) and systematically investigated to resolve this design conflict. Three distinct porosity configurations (S1, S2, S3) were produced by adjusting laser parameters, resulting in increasing open porosity and decreasing wettability (contact angle increased from ∼ 60° in S1 to ∼ 118° in S3). Electrochemical testing demonstrated that the highest-porosity sample (S3) achieved the highest corrosion resistance, with a current density of only 20.18 μA·cm<sup>−2</sup>. Remarkably, despite its low wettability, S3 also exhibited the best PEM cell performance, reaching a peak current density of 29 mA.cm<sup>−2</sup> at 2.0 V, which is more than 20 % of that of S1. This enhancement is attributed to the improved gas/liquid transport efficiency afforded by the interconnected high-porosity network, especially under pressurized flow conditions, which dominates over surface wetting effects. These results highlight that engineering porosity through SLM can simultaneously optimize corrosion resistance and electrochemical output, offering a promising pathway toward more durable and efficient LGDLs for next-generation PEM water electrolyzers in clean hydrogen production systems.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"416 ","pages":"Article 138512"},"PeriodicalIF":7.5,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076211","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}
Pub Date : 2026-01-26DOI: 10.1016/j.fuel.2026.138517
Han Zhang , Yan Wang , Zheng Chen
Super-adiabatic temperature (SAT) has been observed in both experimental and simulated ammonia combustion, yet the underlying chemical kinetics and their dependence on mixture conditions remain incompletely understood. In particular, the elementary reactions that govern SAT and how their contributions vary across different mixture conditions have not been fully assessed. To address this, we conduct a series of 0D homogeneous ignition simulations considering detailed chemical mechanism. The results reveal two distinct SAT regions as the equivalence ratio changes. Region I (ϕ < 3) occurs under moderately rich conditions and is primarily controlled by H2O dissociation (R11: H2O + M ⇌ OH + H + M). In this regime, SAT increases with initial temperature, decreases with pressure, and is strengthened by a higher oxygen volume fraction in the oxidizer. Region II (ϕ ≥ 3) appears under extremely rich conditions, where SAT is dominated by NH3 decomposition (R45: NH3 + M ⇌ NH2 + H + M). In this regime, SAT increases with initial temperature and pressure, while weakly strengthened by oxygen volume fraction. Further simulations with alternative chemical mechanisms confirm the robustness of the two-region SAT behavior. Based on these findings, we compare the SAT phenomena in ammonia and hydrocarbon fuels during ignition and flame processes, highlighting the consistency of their underlying chemical mechanisms and analyzing the differences in their quantitative manifestations. This study provides valuable insights into the kinetic origin of SAT in homogeneous NH3 ignition and may inform future experimental and modelling efforts.
超绝热温度（SAT）已经在实验和模拟氨燃烧中观察到，但潜在的化学动力学及其对混合物条件的依赖仍然不完全清楚。特别是，控制SAT的基本反应及其在不同混合条件下的贡献如何变化尚未得到充分评估。为了解决这个问题，我们进行了一系列的0D均匀点火模拟，考虑了详细的化学机理。结果显示，随着等效比的变化，两个不同的SAT区域。区域I （φ < 3）发生在适度丰富的条件下，主要由H2O解离（R11: H2O + M + OH + H + M）控制。在这种状态下，SAT随初始温度升高而升高，随压力降低而降低，并因氧化剂中氧气体积分数的增加而增强。区域II （φ≥3）出现在极其丰富的条件下，其中SAT以NH3分解为主（R45: NH3 + M + NH2 + H + M）。在这种情况下，SAT随着初始温度和压力的增加而增加，而氧气体积分数的增加对SAT的增强作用较弱。采用其他化学机制的进一步模拟证实了双区SAT行为的鲁棒性。基于这些发现，我们比较了氨和碳氢燃料在点火和燃烧过程中的SAT现象，强调了它们潜在化学机制的一致性，并分析了它们定量表现的差异。这项研究为均匀NH3点火中SAT的动力学起源提供了有价值的见解，并可能为未来的实验和建模工作提供信息。
{"title":"Super-adiabatic temperature in the homogeneous ignition of NH3/O2/N2 mixtures","authors":"Han Zhang , Yan Wang , Zheng Chen","doi":"10.1016/j.fuel.2026.138517","DOIUrl":"10.1016/j.fuel.2026.138517","url":null,"abstract":"<div><div>Super-adiabatic temperature (SAT) has been observed in both experimental and simulated ammonia combustion, yet the underlying chemical kinetics and their dependence on mixture conditions remain incompletely understood. In particular, the elementary reactions that govern SAT and how their contributions vary across different mixture conditions have not been fully assessed. To address this, we conduct a series of 0D homogeneous ignition simulations considering detailed chemical mechanism. The results reveal two distinct SAT regions as the equivalence ratio changes. Region I (<em>ϕ</em> < 3) occurs under moderately rich conditions and is primarily controlled by H<sub>2</sub>O dissociation (R11: H<sub>2</sub>O + M ⇌ OH + H + M). In this regime, SAT increases with initial temperature, decreases with pressure, and is strengthened by a higher oxygen volume fraction in the oxidizer. Region II (<em>ϕ</em> ≥ 3) appears under extremely rich conditions, where SAT is dominated by NH<sub>3</sub> decomposition (R45: NH<sub>3</sub> + M ⇌ NH<sub>2</sub> + H + M). In this regime, SAT increases with initial temperature and pressure, while weakly strengthened by oxygen volume fraction. Further simulations with alternative chemical mechanisms confirm the robustness of the two-region SAT behavior. Based on these findings, we compare the SAT phenomena in ammonia and hydrocarbon fuels during ignition and flame processes, highlighting the consistency of their underlying chemical mechanisms and analyzing the differences in their quantitative manifestations. This study provides valuable insights into the kinetic origin of SAT in homogeneous NH<sub>3</sub> ignition and may inform future experimental and modelling efforts.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"416 ","pages":"Article 138517"},"PeriodicalIF":7.5,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076222","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}
Pub Date : 2026-01-26DOI: 10.1016/j.fuel.2026.138482
Su Wang , Dilong Qiang , Haiting Yan , Zhou Zhou , Mindong Chen , Zhen Li , Songjian Zhao
To effectively remove mercury from sulfur-containing flue gas in non-ferrous metal smelting, a novel Cl-doped CuS (CuS-Cl) material synthesized via a facile coprecipitation-solid phase grinding method. This mechanochemical approach efficiently incorporates Cl atoms into the CuS lattice, inducing structural evolution and creating synergistic S-Cl active sites. In addition, Cl doping also enhances surface acidity, introducing medium-strength acid sites beneficial for adsorption. CuS-Cl achieves near-complete Hg0 removal (>99 %) across an unprecedented wide temperature range (50 ∼ 200 °C) under high Hg0 concentration (∼950 μg/m3), overcoming the temperature limitations of conventional CuS. Remarkably, it maintains > 90 % efficiency even in complex flue gas containing 6000 ppm SO2, 5 % H2O, and 8 % O2. The mechanism analysis results revealed that the synergistic drive of sulfur and chlorine dual sites in CuS-Cl materials is crucial. First, the S22-/Cu2+ active sites on the material surface dominate the chemical adsorption to form HgS. Moreover, lattice Cl combines with generated Hg2+ to form gaseous HgCl2. At low temperatures (<150 °C), Hg0 is primarily immobilized as HgS; at ≥ 150 °C, it is released as HgCl2, preventing adsorbent saturation. This work provides a dual-functional strategy for broad-temperature Hg0 control.
{"title":"Synergistic sulfur-chlorine dual sites drive wide-temperature mercury purification in smelting flue gas","authors":"Su Wang , Dilong Qiang , Haiting Yan , Zhou Zhou , Mindong Chen , Zhen Li , Songjian Zhao","doi":"10.1016/j.fuel.2026.138482","DOIUrl":"10.1016/j.fuel.2026.138482","url":null,"abstract":"<div><div>To effectively remove mercury from sulfur-containing flue gas in non-ferrous metal smelting, a novel Cl-doped CuS (CuS-Cl) material synthesized via a facile coprecipitation-solid phase grinding method. This mechanochemical approach efficiently incorporates Cl atoms into the CuS lattice, inducing structural evolution and creating synergistic S-Cl active sites. In addition, Cl doping also enhances surface acidity, introducing medium-strength acid sites beneficial for adsorption. CuS-Cl achieves near-complete Hg<sup>0</sup> removal (>99 %) across an unprecedented wide temperature range (50 ∼ 200 °C) under high Hg<sup>0</sup> concentration (∼950 μg/m<sup>3</sup>), overcoming the temperature limitations of conventional CuS. Remarkably, it maintains > 90 % efficiency even in complex flue gas containing 6000 ppm SO<sub>2</sub>, 5 % H<sub>2</sub>O, and 8 % O<sub>2</sub>. The mechanism analysis results revealed that the synergistic drive of sulfur and chlorine dual sites in CuS-Cl materials is crucial. First, the S<sub>2</sub><sup>2-</sup>/Cu<sup>2+</sup> active sites on the material surface dominate the chemical adsorption to form HgS. Moreover, lattice Cl combines with generated Hg<sup>2+</sup> to form gaseous HgCl<sub>2</sub>. At low temperatures (<150 °C), Hg<sup>0</sup> is primarily immobilized as HgS; at ≥ 150 °C, it is released as HgCl<sub>2</sub>, preventing adsorbent saturation. This work provides a dual-functional strategy for broad-temperature Hg<sup>0</sup> control.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"416 ","pages":"Article 138482"},"PeriodicalIF":7.5,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076214","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}
Pub Date : 2026-01-26DOI: 10.1016/j.fuel.2026.138486
Qian Xu , Hongfang Jiu , Lixin Zhang , Fengbo Guo , Zhaohui Sui , Xintong Chai , Kai Chen , Yunkai Zhang , Yahui Wang
Atomic doping and defect engineering enhance electron conductivity and increase the number of active sites, optimizing the activation energy of reaction intermediates. This constitutes an effective strategy for boosting the electrocatalytic activity of catalysts. The study employed a cobalt-based catalyst as the support and utilized transition metal vanadium (V) atom doping combined with cerium dioxide (CeO2) modification to synthesize nano-flower-like CoFeV@CeO2. In 1 M KOH electrolyte, the synergistic effect of vanadium doping and CeO2 significantly enhances the catalytic activity of CoFeV@CeO2. Notably, CoFeV@CeO2 exhibits highly efficient bifunctional activity and stability, with overpotentials of only 141 and 124 mV for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at 10 mA cm−2, respectively. This outstanding catalytic performance is attributed to accelerated charge transfer kinetics and enhanced catalytic activity. When used as a bifunctional catalyst for overall water splitting (OWS), it exhibits a low cell voltage of 1.52 V, with the current remaining stable for 50 h. V doping significantly increases both the surface roughness and thickness of CoFeV@CeO2, thereby exposing more active sites. CeO2 modification endowed CoFeV@CeO2 with a three-dimensional nanobranch structure, forming abundant mesopores and micropores between nanosheets, thereby optimizing mass transfer processes. The shift of the d-band center of V and Ce toward the Fermi level demonstrates that the synergistic effect between V and CeO2 enhances the OWS activity of CoFeV@CeO2. This approach provides novel insights and methodologies for designing highly efficient, novel bifunctional integrated water-splitting catalysts.
原子掺杂和缺陷工程提高了电子电导率，增加了活性位点的数量，优化了反应中间体的活化能。这是提高催化剂电催化活性的有效策略。本研究以钴基催化剂为载体，利用过渡金属钒(V)原子掺杂结合二氧化铈（CeO2）改性合成纳米花状CoFeV@CeO2。在1 M KOH电解液中，钒掺杂与CeO2的协同作用显著提高了CoFeV@CeO2的催化活性。值得注意的是，CoFeV@CeO2具有高效的双功能活性和稳定性，在10 mA cm−2下析氢反应（HER）和析氧反应（OER）的过电位分别仅为141和124 mV。这种优异的催化性能归功于加速的电荷转移动力学和增强的催化活性。当作为双功能催化剂用于整体水分解（OWS）时，其电池电压为1.52 V，电流保持稳定50 h。V掺杂显著增加了CoFeV@CeO2的表面粗糙度和厚度，从而暴露出更多的活性位点。CeO2修饰使CoFeV@CeO2具有三维纳米分支结构，在纳米片之间形成丰富的介孔和微孔，从而优化了传质过程。V和Ce的d波段中心向费米能级移动表明，V和CeO2之间的协同作用增强了CoFeV@CeO2的OWS活性。这种方法为设计高效、新颖的双功能集成水分解催化剂提供了新的见解和方法。
{"title":"Defect-rich CeO2 and V doping synergistically modulate the d orbitals of CoFeV-LDH@CeO2 for efficient overall water splitting","authors":"Qian Xu , Hongfang Jiu , Lixin Zhang , Fengbo Guo , Zhaohui Sui , Xintong Chai , Kai Chen , Yunkai Zhang , Yahui Wang","doi":"10.1016/j.fuel.2026.138486","DOIUrl":"10.1016/j.fuel.2026.138486","url":null,"abstract":"<div><div>Atomic doping and defect engineering enhance electron conductivity and increase the number of active sites, optimizing the activation energy of reaction intermediates. This constitutes an effective strategy for boosting the electrocatalytic activity of catalysts. The study employed a cobalt-based catalyst as the support and utilized transition metal vanadium (V) atom doping combined with cerium dioxide (CeO<sub>2</sub>) modification to synthesize nano-flower-like CoFeV@CeO<sub>2</sub>. In 1 M KOH electrolyte, the synergistic effect of vanadium doping and CeO<sub>2</sub> significantly enhances the catalytic activity of CoFeV@CeO<sub>2</sub>. Notably, CoFeV@CeO<sub>2</sub> exhibits highly efficient bifunctional activity and stability, with overpotentials of only 141 and 124 mV for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at 10 mA cm<sup>−2</sup>, respectively. This outstanding catalytic performance is attributed to accelerated charge transfer kinetics and enhanced catalytic activity. When used as a bifunctional catalyst for overall water splitting (OWS), it exhibits a low cell voltage of 1.52 V, with the current remaining stable for 50 h. V doping significantly increases both the surface roughness and thickness of CoFeV@CeO<sub>2</sub>, thereby exposing more active sites. CeO<sub>2</sub> modification endowed CoFeV@CeO<sub>2</sub> with a three-dimensional nanobranch structure, forming abundant mesopores and micropores between nanosheets, thereby optimizing mass transfer processes. The shift of the d-band center of V and Ce toward the Fermi level demonstrates that the synergistic effect between V and CeO<sub>2</sub> enhances the OWS activity of CoFeV@CeO<sub>2</sub>. This approach provides novel insights and methodologies for designing highly efficient, novel bifunctional integrated water-splitting catalysts.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"416 ","pages":"Article 138486"},"PeriodicalIF":7.5,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076213","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}
Pub Date : 2026-01-26DOI: 10.1016/j.fuel.2026.138530
Liwen Chen , Hongjiang Li , Shenmin Li , Yingna Cui , Xinping Wang
To address the problem that the activity degradation of Pt-Zn catalysts in propane dehydrogenation (PDH) process due to Zn loss, PtCu@Zn catalyst being prepared by ion-exchange of Cu(II) together with Pt(II) cations into ZnS-1 channels was studied in this work. It was found that the Cu in PtCu@Zn catalyst is capable of restraining the loss of Zn at high temperature under the reducing gas environment, and that 0.2Pt0.07Cu@2Zn catalyst with nominal metal contents of 0.2 wt% Pt, 0.07 wt% Cu and 2 wt% Zn like 0.2Pt@2Zn, has almost no strong acid site therefore the carbon deposition is considerable slow in the PDH process. The 0.2Pt0.07Cu@2Zn catalyst displayed superior catalytic property and regenerability in 672 h’ long-term reaction including three times’ regeneration. The characterization of the fresh and spent catalysts by ICP, XPS, EDX, and HRTEM indicate that the 0.2Pt0.07Cu@2Zn catalyst has a ternary Pt-Zn-Cu intermetallic alloy (IMA) structure being highly dispersed in zeolite crystals, and that the spent catalyst has a metal atomic ratio of Pt1Zn1.8Cu2.
{"title":"Ternary Pt-Zn-Cu intermetallic alloy dispersed in the MFI zeolite crystals catalyzing propane dehydrogenation","authors":"Liwen Chen , Hongjiang Li , Shenmin Li , Yingna Cui , Xinping Wang","doi":"10.1016/j.fuel.2026.138530","DOIUrl":"10.1016/j.fuel.2026.138530","url":null,"abstract":"<div><div>To address the problem that the activity degradation of Pt-Zn catalysts in propane dehydrogenation (PDH) process due to Zn loss, PtCu@Zn catalyst being prepared by ion-exchange of Cu(II) together with Pt(II) cations into ZnS-1 channels was studied in this work. It was found that the Cu in PtCu@Zn catalyst is capable of restraining the loss of Zn at high temperature under the reducing gas environment, and that 0.2Pt0.07Cu@2Zn catalyst with nominal metal contents of 0.2 wt% Pt, 0.07 wt% Cu and 2 wt% Zn like 0.2Pt@2Zn, has almost no strong acid site therefore the carbon deposition is considerable slow in the PDH process. The 0.2Pt0.07Cu@2Zn catalyst displayed superior catalytic property and regenerability in 672 h’ long-term reaction including three times’ regeneration. The characterization of the fresh and spent catalysts by ICP, XPS, EDX, and HRTEM indicate that the 0.2Pt0.07Cu@2Zn catalyst has a ternary Pt-Zn-Cu intermetallic alloy (IMA) structure being highly dispersed in zeolite crystals, and that the spent catalyst has a metal atomic ratio of Pt<sub>1</sub>Zn<sub>1.8</sub>Cu<sub>2</sub>.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"416 ","pages":"Article 138530"},"PeriodicalIF":7.5,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076215","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}
Pub Date : 2026-01-26DOI: 10.1016/j.fuel.2026.138485
Liang Dong , Tong Zhao , Yahui Cui , Hongjiang Wang
Circulating Fluidisation Method (CFM) demonstrated significant advantages over vortex-based hydrodynamic cavitation and other linear-flow hydrodynamic cavitation methods in terms of both disintegration efficiency and cost-effectiveness, establishing it as an emerging pre-treatment technology for sludge. To elucidate the underlying disintegration mechanisms of CFM, this study focused on the impact of particle density on waste-activated sludge (WAS) disintegration, systematically investigating the intrinsic mechanisms involved. Biochemical analyses, rheological testing, and kinetic experiments coupled with modelling were employed to unveil these mechanisms. The results indicated that under the same particle size and filling ratio conditions, soluble chemical oxygen demand (SCOD), disintegration degree (DDSCOD), DNA, protein, and carbohydrate values increased with the higher particle density. At a particle filling ratio of 1.5%, with a treatment frequency of 39.3 Hz for 60 min, zirconia achieved SCOD, DDSCOD, DNA, protein, and carbohydrate disintegration levels that were 1.36, 1.37, 1.39, 1.29, and 2.38 times higher, respectively, than those achieved by glass beads. Under high inlet pressure or elevated particle filling ratios, the apparent viscosity of sludge decreases with increasing particle density (with a maximum reduction of 18.48%), thereby enhancing the disintegration efficiency. The mechanistic study reveals that the primary process influencing the disintegration efficiency with increasing particle density was the enhanced collision intensity of particles. The diminishing disparity in disintegration efficiency among particles of different densities as inlet pressure increases is primarily attributed to the stronger cavitation effect, liquid-phase shear force, and centrifugal force exhibited by low-density particles, despite their lower collision intensity.
{"title":"Mechanism of particle-density-regulated sludge disintegration in the circulating fluidisation method: The trade-off between collision intensity and cavitation effects","authors":"Liang Dong , Tong Zhao , Yahui Cui , Hongjiang Wang","doi":"10.1016/j.fuel.2026.138485","DOIUrl":"10.1016/j.fuel.2026.138485","url":null,"abstract":"<div><div>Circulating Fluidisation Method (CFM) demonstrated significant advantages over vortex-based hydrodynamic cavitation and other linear-flow hydrodynamic cavitation methods in terms of both disintegration efficiency and cost-effectiveness, establishing it as an emerging pre-treatment technology for sludge. To elucidate the underlying disintegration mechanisms of CFM, this study focused on the impact of particle density on waste-activated sludge (WAS) disintegration, systematically investigating the intrinsic mechanisms involved. Biochemical analyses, rheological testing, and kinetic experiments coupled with modelling were employed to unveil these mechanisms. The results indicated that under the same particle size and filling ratio conditions, soluble chemical oxygen demand (SCOD), disintegration degree (<em>DD</em><sub>SCOD</sub>), DNA, protein, and carbohydrate values increased with the higher particle density. At a particle filling ratio of 1.5%, with a treatment frequency of 39.3 Hz for 60 min, zirconia achieved SCOD, <em>DD</em><sub>SCOD</sub>, DNA, protein, and carbohydrate disintegration levels that were 1.36, 1.37, 1.39, 1.29, and 2.38 times higher, respectively, than those achieved by glass beads. Under high inlet pressure or elevated particle filling ratios, the apparent viscosity of sludge decreases with increasing particle density (with a maximum reduction of 18.48%), thereby enhancing the disintegration efficiency. The mechanistic study reveals that the primary process influencing the disintegration efficiency with increasing particle density was the enhanced collision intensity of particles. The diminishing disparity in disintegration efficiency among particles of different densities as inlet pressure increases is primarily attributed to the stronger cavitation effect, liquid-phase shear force, and centrifugal force exhibited by low-density particles, despite their lower collision intensity.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"416 ","pages":"Article 138485"},"PeriodicalIF":7.5,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076212","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}
Pyrolysis is an important thermochemical conversion process for biomass and is conducted in the absence of oxygen at temperatures between 400 and 1000 C. Biomass pyrolysis yields cleaner combustion fuels by decreasing fuel-bound oxygen and nitrogen species, thus reducing NOX formation and net emissions. A structural model compound for cyclic peptides — important nitrogen-containing components in biomass — is 2,5-diketopiperazine (DKP). In this work, we apply an automated workflow that combines reactive molecular dynamics simulations with electronic structure calculations at different levels of theory to develop a detailed kinetic model for the pyrolysis of DKP at the level of elementary reaction steps. This complements previous studies that focused only on the net reaction scheme. The developed DKP kinetic submodel for pyrolysis is implemented in the kinetic modeling software OpenSMOKE++. Under pyrolysis, DKP decomposes into hydrogen cyanide (), carbon monoxide () and hydrogen (). Ammonia () is not formed in primary decomposition steps but rather in secondary reactions involving the primary intermediates. The submodel qualitatively reproduces DKP pyrolysis products observed in a fluidized bed reactor under kinetically controlled conditions and provides a reliable basis for further studies on peptide decomposition. Beyond the specific kinetic submodel, this work proposes a general workflow for investigating thermal decomposition and combustion processes.
{"title":"Computational study on the pyrolysis of 2,5-diketopiperazine: From electronic structure calculations to kinetic modeling","authors":"Bastian Schnieder , Paulo Debiagi , Matteo Pelucchi , Rochus Schmid , Christof Hättig","doi":"10.1016/j.fuel.2026.138472","DOIUrl":"10.1016/j.fuel.2026.138472","url":null,"abstract":"<div><div>Pyrolysis is an important thermochemical conversion process for biomass and is conducted in the absence of oxygen at temperatures between 400 and 1000 <span><math><msup><mspace></mspace><mo>∘</mo></msup></math></span>C. Biomass pyrolysis yields cleaner combustion fuels by decreasing fuel-bound oxygen and nitrogen species, thus reducing NO<sub>X</sub> formation and net <span><math><msub><mrow><mi>CO</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> emissions. A structural model compound for cyclic peptides — important nitrogen-containing components in biomass — is 2,5-diketopiperazine (DKP). In this work, we apply an automated workflow that combines reactive molecular dynamics simulations with electronic structure calculations at different levels of theory to develop a detailed kinetic model for the pyrolysis of DKP at the level of elementary reaction steps. This complements previous studies that focused only on the net reaction scheme. The developed DKP kinetic submodel for pyrolysis is implemented in the kinetic modeling software <span>OpenSMOKE++</span>. Under pyrolysis, DKP decomposes into hydrogen cyanide (<span><math><mrow><mi>HCN</mi></mrow></math></span>), carbon monoxide (<span><math><mrow><mi>CO</mi></mrow></math></span>) and hydrogen (<span><math><msub><mrow><mi>H</mi></mrow><mn>2</mn></msub></math></span>). Ammonia (<span><math><msub><mrow><mi>NH</mi></mrow><mn>3</mn></msub></math></span>) is not formed in primary decomposition steps but rather in secondary reactions involving the primary intermediates. The submodel qualitatively reproduces DKP pyrolysis products observed in a fluidized bed reactor under kinetically controlled conditions and provides a reliable basis for further studies on peptide decomposition. Beyond the specific kinetic submodel, this work proposes a general workflow for investigating thermal decomposition and combustion processes.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"416 ","pages":"Article 138472"},"PeriodicalIF":7.5,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037028","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}
Pub Date : 2026-01-25DOI: 10.1016/j.fuel.2026.138441
Kodai Nonomura, Tsukasa Hori, Yinan Yang, Shinya Sawada, Fumiteru Akamatsu
Ammonia-hydrocarbon co-firing is gaining attention as a way to overcome ammonia’s low reactivity and heating value in the push toward carbon neutrality. Recent fundamental studies have shown that hydrocarbon-NOx interactions promote combustion at low-to-intermediate temperatures by influencing the oxidation onset of hydrocarbons and NOx distribution. The present study aims to investigate the effects of these interactions on flame characteristics and exhaust NO emissions in a semi-industrial-scale ammonia/city gas co-firing combustion system. A three-dimensional numerical simulation of a 10 kW industrial ammonia co-firing air-staged furnace was conducted using the CRECK mechanism, which incorporates detailed hydrocarbon–NOx interactions. As a result, it was confirmed that the promotion of hydrocarbon oxidation by NOx at low-to-intermediate temperatures due to hydrocarbon–NOx interactions included in the CRECK mechanism can be observed over a wide range of ammonia co-firing ratios. Analysis of the rate of production (ROP) of NO revealed that this effect is particularly pronounced below approximately 1200 K, compared to the other mechanism that provides a simplified treatment of such interactions, and the reaction in which promotes the oxidation of was found to be the most significant in the hydrocarbon–NOx interactions. ROP analysis for NO showed that these interactions accounted for up to approximately half of the total ROP of NO-related reactions in the low-to-intermediate temperature regions below 1200 K at the co-firing ratio of 10%. These findings provide important insights into the combustion behavior inside ammonia/city gas co-firing furnaces.
{"title":"The effect of hydrocarbon–NOx interactions in the low-to-intermediate temperature range on the prediction of combustion behavior in a 10 kW ammonia/City gas co-firing furnace","authors":"Kodai Nonomura, Tsukasa Hori, Yinan Yang, Shinya Sawada, Fumiteru Akamatsu","doi":"10.1016/j.fuel.2026.138441","DOIUrl":"10.1016/j.fuel.2026.138441","url":null,"abstract":"<div><div>Ammonia-hydrocarbon co-firing is gaining attention as a way to overcome ammonia’s low reactivity and heating value in the push toward carbon neutrality. Recent fundamental studies have shown that hydrocarbon-NOx interactions promote combustion at low-to-intermediate temperatures by influencing the oxidation onset of hydrocarbons and NOx distribution. The present study aims to investigate the effects of these interactions on flame characteristics and exhaust NO emissions in a semi-industrial-scale ammonia/city gas co-firing combustion system. A three-dimensional numerical simulation of a 10 kW industrial ammonia co-firing air-staged furnace was conducted using the CRECK mechanism, which incorporates detailed hydrocarbon–NOx interactions. As a result, it was confirmed that the promotion of hydrocarbon oxidation by NOx at low-to-intermediate temperatures due to hydrocarbon–NOx interactions included in the CRECK mechanism can be observed over a wide range of ammonia co-firing ratios. Analysis of the rate of production (ROP) of NO revealed that this effect is particularly pronounced below approximately 1200 K, compared to the other mechanism that provides a simplified treatment of such interactions, and the reaction in which <span><math><mrow><msub><mrow><mi>NO</mi></mrow><mn>2</mn></msub></mrow></math></span> promotes the oxidation of <span><math><mrow><msub><mrow><mi>CH</mi></mrow><mn>3</mn></msub></mrow></math></span> was found to be the most significant in the hydrocarbon–NOx interactions. ROP analysis for NO showed that these interactions accounted for up to approximately half of the total ROP of NO-related reactions in the low-to-intermediate temperature regions below 1200 K at the co-firing ratio of 10%. These findings provide important insights into the combustion behavior inside ammonia/city gas co-firing furnaces.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"416 ","pages":"Article 138441"},"PeriodicalIF":7.5,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037029","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}
Experimental study was conducted to investigate the combustion and emission characteristics of NH3/CH4 axial-staging flames in both premixed and non-premixed modes. The effects and optimal parameters of staged-air-ratio (SAR) and staged-air-injection-height (H) on flame topology and CO/NO emission characteristics in different combustion modes are systematically investigated. Reynolds-Averaged Navier-Stokes (RANS) simulation was also performed to analyze the flow field structure as well as the species spatial distributions in different combustion modes, revealing the different influential mechanisms of staged air on combustion. The results indicate that in premixed mode, the optimal conditions are SAR = 30% ( primary = 1.21) and H = 80 mm, resulting in a NO emission of 270 ppmvd (at 6% O2) and zero CO emission. While in non-premixed mode, the optimal conditions are SAR = 20% ( primary = 1.06) and H = 100 mm, resulting in a NO emission of 378 ppmvd (at 6% O2) with zero CO emission. Comparing to premixed mode, the combustion efficiency in non-premixed mode is significantly affected since H2 emission can be detected across all air-staged conditions. The radial injection momentum of fuel in non-premixed mode causes its NO formation zone to be distributed closer to the combustion chamber wall as well as downstream regions. This distribution characteristic leads to differential effects of staged-air on the fuel-rich conditions in the primary combustion zone, while also resulting in varying required secondary residence times. The synergy influence of these two factors causes the optimal air-staging parameters in non-premixed mode to be different from those in premixed mode.
{"title":"Optimal operating parameters for NH3/CH4 axial-staging combustion under different fuel/air mixing patterns towards cleaner emission","authors":"Zirui Liu, Yaojie Tu, Zhixin Huang, Jiajun Yu, Pengfei Li, Hao Liu, Shihong Zhang, Zixue Luo","doi":"10.1016/j.fuel.2026.138476","DOIUrl":"10.1016/j.fuel.2026.138476","url":null,"abstract":"<div><div>Experimental study was conducted to investigate the combustion and emission characteristics of NH<sub>3</sub>/CH<sub>4</sub> axial-staging flames in both premixed and non-premixed modes. The effects and optimal parameters of staged-air-ratio (SAR) and staged-air-injection-height (H) on flame topology and CO/NO emission characteristics in different combustion modes are systematically investigated. Reynolds-Averaged Navier-Stokes (RANS) simulation was also performed to analyze the flow field structure as well as the species spatial distributions in different combustion modes, revealing the different influential mechanisms of staged air on combustion. The results indicate that in premixed mode, the optimal conditions are SAR = 30% (<span><math><mi>φ</mi></math></span> <sub>primary</sub> = 1.21) and H = 80 mm, resulting in a NO emission of 270 ppmvd (at 6% O<sub>2</sub>) and zero CO emission. While in non-premixed mode, the optimal conditions are SAR = 20% (<span><math><mi>φ</mi></math></span> <sub>primary</sub> = 1.06) and H = 100 mm, resulting in a NO emission of 378 ppmvd (at 6% O<sub>2</sub>) with zero CO emission. Comparing to premixed mode, the combustion efficiency in non-premixed mode is significantly affected since H<sub>2</sub> emission can be detected across all air-staged conditions. The radial injection momentum of fuel in non-premixed mode causes its NO formation zone to be distributed closer to the combustion chamber wall as well as downstream regions. This distribution characteristic leads to differential effects of staged-air on the fuel-rich conditions in the primary combustion zone, while also resulting in varying required secondary residence times. The synergy influence of these two factors causes the optimal air-staging parameters in non-premixed mode to be different from those in premixed mode.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"416 ","pages":"Article 138476"},"PeriodicalIF":7.5,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037030","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}
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