Pub Date : 2026-01-30DOI: 10.1016/j.joei.2026.102458
Yu Li , Lei Wang , Cheng Shen , Xin Liu , Bo Xiong , Zuojun Li , Jie Chen , Laihong Shen
The existence of H2S results in sulfurization of oxygen carrier materials, poisoning and deactivating them during chemical looping combustion. Sulfur-related reactions over the CoFe2O4 (100) surface were deeply explored by density functional theory and thermodynamic calculations. Adsorption intensity for sulfur species is in the order of S* > HS* > H2S* on CoFe2O4. The step of HS* + * → S* + H* acts as the rate-controlling stage for H2S dissociation. The separated H atoms may react with surface O atoms and generate gaseous H2O, which is activated by 2.31 eV. The S atom will fill the oxygen vacancies and made CoFe2O4 inactivated. The dissociated S atoms may seize the surface oxygen that was originally intended for reacting with the fuel molecules, leading to SO2 formation, and the corresponding energy barrier is 1.07 eV. Kinetically, SO2 formation is significantly easier than H2O formation during sulfur-related reactions upon CoFe2O4. Sulfur impurities in CLC not only contaminate the oxygen carrier but also reduce the conversion efficiency.
{"title":"Study on sulfur-related reactions with Co-Fe spinel during chemical looping: A mechanistic research","authors":"Yu Li , Lei Wang , Cheng Shen , Xin Liu , Bo Xiong , Zuojun Li , Jie Chen , Laihong Shen","doi":"10.1016/j.joei.2026.102458","DOIUrl":"10.1016/j.joei.2026.102458","url":null,"abstract":"<div><div>The existence of H<sub>2</sub>S results in sulfurization of oxygen carrier materials, poisoning and deactivating them during chemical looping combustion. Sulfur-related reactions over the CoFe<sub>2</sub>O<sub>4</sub> (100) surface were deeply explored by density functional theory and thermodynamic calculations. Adsorption intensity for sulfur species is in the order of S* > HS* > H<sub>2</sub>S* on CoFe<sub>2</sub>O<sub>4</sub>. The step of HS* + * → S* + H* acts as the rate-controlling stage for H<sub>2</sub>S dissociation. The separated H atoms may react with surface O atoms and generate gaseous H<sub>2</sub>O, which is activated by 2.31 eV. The S atom will fill the oxygen vacancies and made CoFe<sub>2</sub>O<sub>4</sub> inactivated. The dissociated S atoms may seize the surface oxygen that was originally intended for reacting with the fuel molecules, leading to SO<sub>2</sub> formation, and the corresponding energy barrier is 1.07 eV. Kinetically, SO<sub>2</sub> formation is significantly easier than H<sub>2</sub>O formation during sulfur-related reactions upon CoFe<sub>2</sub>O<sub>4</sub>. Sulfur impurities in CLC not only contaminate the oxygen carrier but also reduce the conversion efficiency.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"125 ","pages":"Article 102458"},"PeriodicalIF":6.2,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146188709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Direct hydrogen injectors are actively being developed today to enable high-flow-rate injection of hydrogen into the engine cylinders at low pressure to promote opportunities for hydrogen application to internal combustion engines. In this study, the effect of high-flow-rate injection by direct hydrogen injectors on engine performance was evaluated under low hydrogen supply pressure. Combustion tests of a spark-ignition hydrogen engine were combined with a computational fluid dynamics analysis of jet and mixture formation behavior using large eddy simulation (LES). The results of this study revealed that a reduction of cooling losses accompanying attenuation of in-cylinder gas flow and changes in mixture location due to high-flow-rate injection contributed to a large improvement of thermal efficiency by 2–3%. This indicates that high-flow-rate injection in low-pressure direct-injection hydrogen engines is not only essential for achieving high power output through supercharging, but it is also effective in improving thermal efficiency by optimizing the injection timing.
{"title":"Experimental and numerical investigation of high-flow-rate injection focusing on improved thermal efficiency and output performance in low-pressure direct-injection hydrogen engines","authors":"Nobuhiro Shimmura , Masakuni Oikawa , Seiya Yamada , Yuji Mihara , Yasuo Takagi","doi":"10.1016/j.joei.2026.102463","DOIUrl":"10.1016/j.joei.2026.102463","url":null,"abstract":"<div><div>Direct hydrogen injectors are actively being developed today to enable high-flow-rate injection of hydrogen into the engine cylinders at low pressure to promote opportunities for hydrogen application to internal combustion engines. In this study, the effect of high-flow-rate injection by direct hydrogen injectors on engine performance was evaluated under low hydrogen supply pressure. Combustion tests of a spark-ignition hydrogen engine were combined with a computational fluid dynamics analysis of jet and mixture formation behavior using large eddy simulation (LES). The results of this study revealed that a reduction of cooling losses accompanying attenuation of in-cylinder gas flow and changes in mixture location due to high-flow-rate injection contributed to a large improvement of thermal efficiency by 2–3%. This indicates that high-flow-rate injection in low-pressure direct-injection hydrogen engines is not only essential for achieving high power output through supercharging, but it is also effective in improving thermal efficiency by optimizing the injection timing.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"125 ","pages":"Article 102463"},"PeriodicalIF":6.2,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146188711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2026-01-29DOI: 10.1016/j.joei.2026.102460
Tianye Wang , Cheng Xu , Guofu Xia, Fuli Wen, Rongjun Zhang, Jiakang Deng, Hongwei Li
Industrial implementation of methane dry reforming is frequently hindered by rapid deactivation of Ni catalysts, driven mainly by particle growth and carbon accumulation. To address these challenges, Ni/MgAl2O4 catalysts incorporating La, Ce, or Y were engineered using a co-impregnation strategy combined with an ordered mesoporous MgAl2O4 framework. Comprehensive characterization revealed that the mesoporous architecture effectively confined Ni species below 5 nm, while promoter-dependent structural regulation played a decisive role in long-term stability. La preserved the hexagonally ordered channels and strengthened metal–support interactions, resulting in markedly reduced sintering and a substantial decrease in carbon deposition during 432 h operation. Ce enhanced CO2 activation through redox cycling but generated excessive methane-cracking carbon, compromising durability, whereas Y disrupted mesopore ordering and intensified Ni agglomeration. The La-modified catalyst ultimately maintained nearly constant CH4 and CO2 conversions at 750 °C with minimal activity loss, demonstrating the synergistic advantages of spatial confinement and promoter-induced chemical stabilization. This work provides mechanistic insights into rare-earth–regulated Ni catalysts and establishes a design basis for thermally robust DRM systems.
{"title":"Rare-earth–modulated ordered mesoporous MgAl2O4 enabling ultra-stable Ni catalysts for methane dry reforming","authors":"Tianye Wang , Cheng Xu , Guofu Xia, Fuli Wen, Rongjun Zhang, Jiakang Deng, Hongwei Li","doi":"10.1016/j.joei.2026.102460","DOIUrl":"10.1016/j.joei.2026.102460","url":null,"abstract":"<div><div>Industrial implementation of methane dry reforming is frequently hindered by rapid deactivation of Ni catalysts, driven mainly by particle growth and carbon accumulation. To address these challenges, Ni/MgAl<sub>2</sub>O<sub>4</sub> catalysts incorporating La, Ce, or Y were engineered using a co-impregnation strategy combined with an ordered mesoporous MgAl<sub>2</sub>O<sub>4</sub> framework. Comprehensive characterization revealed that the mesoporous architecture effectively confined Ni species below 5 nm, while promoter-dependent structural regulation played a decisive role in long-term stability. La preserved the hexagonally ordered channels and strengthened metal–support interactions, resulting in markedly reduced sintering and a substantial decrease in carbon deposition during 432 h operation. Ce enhanced CO<sub>2</sub> activation through redox cycling but generated excessive methane-cracking carbon, compromising durability, whereas Y disrupted mesopore ordering and intensified Ni agglomeration. The La-modified catalyst ultimately maintained nearly constant CH<sub>4</sub> and CO<sub>2</sub> conversions at 750 °C with minimal activity loss, demonstrating the synergistic advantages of spatial confinement and promoter-induced chemical stabilization. This work provides mechanistic insights into rare-earth–regulated Ni catalysts and establishes a design basis for thermally robust DRM systems.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"125 ","pages":"Article 102460"},"PeriodicalIF":6.2,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146188712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2026-01-28DOI: 10.1016/j.joei.2026.102459
Jianglong Pu, Tianyu Yu, Ning Ai, Hui Wang
Designing efficient and stable catalysts is crucial for sustainable hydrogen production from biomass via steam reforming. A Ni/CeBO3 catalyst with strong metal–support interactions (SMSIs) was synthesized through an insitu co-reduction strategy. The effects of nickel content and thermal treatment were systematically investigated, revealing that calcination is critical for forming crystalline CeBO3 during the reduction process, which governs catalytic performance. SMSIs increase the reduction temperature required for Ni0 activation, while higher Ni loading or reduction temperature induces a structural transition from monoclinic (m-) to orthorhombic (o-) CeBO3. Density functional theory (DFT) calculations indicate that Ni4 clusters on m-CeBO3 exhibit favorable adsorption geometries and higher reactivity, whereas o-CeBO3 supports generate inert configurations. Catalysts supported on m-CeBO3 show enhanced coke resistance and suppressed acetone formation. Maintaining Ni0 exposure and preserving the m-CeBO3 phase are therefore essential for high activity, achievable by controlling reduction temperature and Ni loading. The optimized 20Ni/CeBO3-600 catalyst retains the m-phase and delivers stable hydrogen production with <3 % decline over 60 h, performing efficiently under low reaction temperatures and steam-to-carbon ratios. These findings clarify the role of m-CeBO3 and provide mechanistic insight for rational design of high-performance catalysts in biomass-to-hydrogen conversion.
{"title":"Phase-controlled CeBO3 supports for Ni-based catalysts: DFT and experimental insights into structure–reactivity relationships in acetic acid steam reforming","authors":"Jianglong Pu, Tianyu Yu, Ning Ai, Hui Wang","doi":"10.1016/j.joei.2026.102459","DOIUrl":"10.1016/j.joei.2026.102459","url":null,"abstract":"<div><div>Designing efficient and stable catalysts is crucial for sustainable hydrogen production from biomass via steam reforming. A Ni/CeBO<sub>3</sub> catalyst with strong metal–support interactions (SMSIs) was synthesized through an <em>in</em> <em>situ</em> co-reduction strategy. The effects of nickel content and thermal treatment were systematically investigated, revealing that calcination is critical for forming crystalline CeBO<sub>3</sub> during the reduction process, which governs catalytic performance. SMSIs increase the reduction temperature required for Ni<sup>0</sup> activation, while higher Ni loading or reduction temperature induces a structural transition from monoclinic (m-) to orthorhombic (o-) CeBO<sub>3</sub>. Density functional theory (DFT) calculations indicate that Ni<sub>4</sub> clusters on m-CeBO<sub>3</sub> exhibit favorable adsorption geometries and higher reactivity, whereas o-CeBO<sub>3</sub> supports generate inert configurations. Catalysts supported on m-CeBO<sub>3</sub> show enhanced coke resistance and suppressed acetone formation. Maintaining Ni<sup>0</sup> exposure and preserving the m-CeBO<sub>3</sub> phase are therefore essential for high activity, achievable by controlling reduction temperature and Ni loading. The optimized 20Ni/CeBO<sub>3</sub>-600 catalyst retains the m-phase and delivers stable hydrogen production with <3 % decline over 60 h, performing efficiently under low reaction temperatures and steam-to-carbon ratios. These findings clarify the role of m-CeBO<sub>3</sub> and provide mechanistic insight for rational design of high-performance catalysts in biomass-to-hydrogen conversion.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"125 ","pages":"Article 102459"},"PeriodicalIF":6.2,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146188710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2026-01-28DOI: 10.1016/j.joei.2026.102462
Daoxuan Sun , Weidong Nie , Shue Tian , Dong Han , Laizhi Sun , Lei Chen , Shuangxia Yang , Tianjin Li , Zhiguo Dong , Baofeng Zhao , Meirong Xu , Xinping Xie , Hongyu Si , Dongliang Hua
The catalytic pyrolysis of high-density polyethylene (HDPE) over the Zn modified ZSM-5 zeolite catalysts was systematically examined to improve the yield of aromatic hydrocarbons. The Zn/ZSM-5 catalysts with different zinc loadings were synthesized by the incipient wetness impregnation method and thoroughly characterized by the BET, XRD, NH3-TPD, SEM, and TG techniques. The influences of the Zn content, the reaction temperature, and the catalyst-to-feedstock mass ratio on the distribution of products and the selectivity of aromatics were investigated. The results indicated that under the optimized conditions of 5 % Zn loading, the reaction temperature of 450 °C, and the catalyst-to-feedstock mass ratio of 2/1, the selectivity of monocyclic aromatic hydrocarbons (MAHs) reached 85.65 %, while the selectivity of benzene, toluene, ethylbenzene, and xylene (BTEX) was as high as 62.06 %. The 5 % Zn/ZSM-5 catalyst also exhibited the excellent structural stability and retained about 85 % selectivity of MAHs after 10 successive cycles. The characterization analyses confirmed that the incorporation of Zn metal altered the pore environment and the acidity profile of the ZSM-5, thereby enhancing the dehydrogenation and aromatization of the pyrolytic intermediates. A reaction mechanism of the catalytic pyrolysis of HDPE over the Zn/ZSM-5 was proposed, suggesting that the generation of the aromatic hydrocarbons was promoted through the hydrogen-transfer, oligomerization, and cyclization pathways. These findings demonstrated that the Zn/ZSM-5 catalysts provide a promising strategy for the selective conversion of plastic waste into the value-added aromatic hydrocarbons.
{"title":"Catalytic pyrolysis of plastic to produce aromatic hydrocarbons over the Zn modified ZSM-5 catalysts","authors":"Daoxuan Sun , Weidong Nie , Shue Tian , Dong Han , Laizhi Sun , Lei Chen , Shuangxia Yang , Tianjin Li , Zhiguo Dong , Baofeng Zhao , Meirong Xu , Xinping Xie , Hongyu Si , Dongliang Hua","doi":"10.1016/j.joei.2026.102462","DOIUrl":"10.1016/j.joei.2026.102462","url":null,"abstract":"<div><div>The catalytic pyrolysis of high-density polyethylene (HDPE) over the Zn modified ZSM-5 zeolite catalysts was systematically examined to improve the yield of aromatic hydrocarbons. The Zn/ZSM-5 catalysts with different zinc loadings were synthesized by the incipient wetness impregnation method and thoroughly characterized by the BET, XRD, NH<sub>3</sub>-TPD, SEM, and TG techniques. The influences of the Zn content, the reaction temperature, and the catalyst-to-feedstock mass ratio on the distribution of products and the selectivity of aromatics were investigated. The results indicated that under the optimized conditions of 5 % Zn loading, the reaction temperature of 450 °C, and the catalyst-to-feedstock mass ratio of 2/1, the selectivity of monocyclic aromatic hydrocarbons (MAHs) reached 85.65 %, while the selectivity of benzene, toluene, ethylbenzene, and xylene (BTEX) was as high as 62.06 %. The 5 % Zn/ZSM-5 catalyst also exhibited the excellent structural stability and retained about 85 % selectivity of MAHs after 10 successive cycles. The characterization analyses confirmed that the incorporation of Zn metal altered the pore environment and the acidity profile of the ZSM-5, thereby enhancing the dehydrogenation and aromatization of the pyrolytic intermediates. A reaction mechanism of the catalytic pyrolysis of HDPE over the Zn/ZSM-5 was proposed, suggesting that the generation of the aromatic hydrocarbons was promoted through the hydrogen-transfer, oligomerization, and cyclization pathways. These findings demonstrated that the Zn/ZSM-5 catalysts provide a promising strategy for the selective conversion of plastic waste into the value-added aromatic hydrocarbons.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"125 ","pages":"Article 102462"},"PeriodicalIF":6.2,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2026-01-28DOI: 10.1016/j.joei.2026.102467
Qinlong Hu, Haoyang Lou, Zhuqing Niu, Jiankai Zhang, Xinjia Wang, Hui Jin, Zhongming Bu, Guoneng Li, Yuanjun Tang, Chao Ye
This study systematically explores nickel-based HZSM-5 zeolite activated by NaOH treatment in different atmospheres (air and CO2), revealing the intricate synergistic mechanisms between structure, acidity, and metal active sites during the catalytic cracking of toluene. The research found that the pore structure and acid site distribution of the catalyst can be directionally tuned through the choice of atmosphere: air activation primarily expands mesopores and optimizes mass transfer, while CO2 activation finely tunes the acid sites, significantly enhancing the weak and medium-strength acid sites, thereby constructing a rich reactive interface for the adsorption and initial activation of toluene. In the reaction pathway, a significant synergistic effect between the metal and the support was observed: nickel species were reduced to highly dispersed nanoparticles, serving as the core sites for activating C-H and C-C bonds, which cooperated with the acidic centers of the zeolite to promote the cleavage of toluene molecules and the opening of the benzene ring, ultimately converting them into small molecule synthesis gas. Under conditions of 7% nickel loading and CO2 activation, the maximum toluene conversion rate reached 78.92%. The flow-mass transfer-reaction coupling model constructed using COMSOL successfully replicated the experimental trends (simulation efficiency 79%) and clarified that temperature and feed flow rate are key operational parameters affecting the cracking behavior. From the perspectives of "structure-acidity synergy" and "metal-support interaction," this study deepens the understanding of the micro-mechanism of toluene catalytic cracking, providing a theoretical basis for the rational design of catalysts and process optimization.
{"title":"A combined experimental and simulation study on toluene cracking: synergistic strategy of Ni loading, alkali treatment, and atmosphere activation on HZSM-5 zeolite","authors":"Qinlong Hu, Haoyang Lou, Zhuqing Niu, Jiankai Zhang, Xinjia Wang, Hui Jin, Zhongming Bu, Guoneng Li, Yuanjun Tang, Chao Ye","doi":"10.1016/j.joei.2026.102467","DOIUrl":"10.1016/j.joei.2026.102467","url":null,"abstract":"<div><div>This study systematically explores nickel-based HZSM-5 zeolite activated by NaOH treatment in different atmospheres (air and CO<sub>2</sub>), revealing the intricate synergistic mechanisms between structure, acidity, and metal active sites during the catalytic cracking of toluene. The research found that the pore structure and acid site distribution of the catalyst can be directionally tuned through the choice of atmosphere: air activation primarily expands mesopores and optimizes mass transfer, while CO<sub>2</sub> activation finely tunes the acid sites, significantly enhancing the weak and medium-strength acid sites, thereby constructing a rich reactive interface for the adsorption and initial activation of toluene. In the reaction pathway, a significant synergistic effect between the metal and the support was observed: nickel species were reduced to highly dispersed nanoparticles, serving as the core sites for activating C-H and C-C bonds, which cooperated with the acidic centers of the zeolite to promote the cleavage of toluene molecules and the opening of the benzene ring, ultimately converting them into small molecule synthesis gas. Under conditions of 7% nickel loading and CO<sub>2</sub> activation, the maximum toluene conversion rate reached 78.92%. The flow-mass transfer-reaction coupling model constructed using COMSOL successfully replicated the experimental trends (simulation efficiency 79%) and clarified that temperature and feed flow rate are key operational parameters affecting the cracking behavior. From the perspectives of \"structure-acidity synergy\" and \"metal-support interaction,\" this study deepens the understanding of the micro-mechanism of toluene catalytic cracking, providing a theoretical basis for the rational design of catalysts and process optimization.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"125 ","pages":"Article 102467"},"PeriodicalIF":6.2,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2026-01-27DOI: 10.1016/j.joei.2026.102466
Duc-Thang Tran , Nguyen-Phuong Nguyen , Thanh-Linh H. Duong , Anh Minh-Nhat Lai , Quang-Long Nguyen , Minh-Tuan Nguyen-Dinh , Tri Nguyen , Hoang-Duy P. Nguyen , Thuy-Phuong T. Pham
Mitigation of CO2 emissions has become a global challenge, and its catalytic conversion to CH4 represents a promising route for carbon utilization as well as renewable fuel production. In this work, a series of Ni/SiO2 catalysts were synthesized via wet impregnation, a modified sol-gel process, and a combined sol-gel/post-impregnation approach to balance embedded and surface Ni species for efficient CO2 methanation. The as-prepared, reduced and spent catalysts were characterized by XRD, N2 physisorption, TEM, H2-TPR, CO2-TPD, H2-TPD and TPO to correlate structural properties with catalytic performance. The Ni-embedded SiO2 catalyst (20Ni-SiO2) exhibited higher BET surface area, uniform mesoporosity, better dispersion and stronger MSI compared to the impregnated 20Ni/SiO2, highlighting the importance of sol-gel incorporation in texture control. Interestingly, CO2-TPD revealed greater CO2 adsorption ability for impregnated Ni species, whereas H2-TPD indicated superior hydrogen dissociation activity for embedded Ni species. Consequently, due to the synergistic contribution of embedded and surface Ni species, the post-impregnated 10Ni/(20Ni-SiO2) catalyst achieved 81.6 % CO2 conversion and 99.5 % CH4 selectivity at 350 °C, outperforming conventional impregnated and sol-gel catalysts. Stability tests and TPO profiles confirm that the 10Ni/(20Ni-SiO2) catalyst maintains efficient performance over 100 h, with only a 5 % decrease in CO2 conversion, negligible change in CH4 selectivity, and excellent resistance to coke formation.
{"title":"Enhanced CO2 methanation over SiO2-supported catalysts with embedded and surface Ni sites","authors":"Duc-Thang Tran , Nguyen-Phuong Nguyen , Thanh-Linh H. Duong , Anh Minh-Nhat Lai , Quang-Long Nguyen , Minh-Tuan Nguyen-Dinh , Tri Nguyen , Hoang-Duy P. Nguyen , Thuy-Phuong T. Pham","doi":"10.1016/j.joei.2026.102466","DOIUrl":"10.1016/j.joei.2026.102466","url":null,"abstract":"<div><div>Mitigation of CO<sub>2</sub> emissions has become a global challenge, and its catalytic conversion to CH<sub>4</sub> represents a promising route for carbon utilization as well as renewable fuel production. In this work, a series of Ni/SiO<sub>2</sub> catalysts were synthesized via wet impregnation, a modified sol-gel process, and a combined sol-gel/post-impregnation approach to balance embedded and surface Ni species for efficient CO<sub>2</sub> methanation. The as-prepared, reduced and spent catalysts were characterized by XRD, N<sub>2</sub> physisorption, TEM, H<sub>2</sub>-TPR, CO<sub>2</sub>-TPD, H<sub>2</sub>-TPD and TPO to correlate structural properties with catalytic performance. The Ni-embedded SiO<sub>2</sub> catalyst (20Ni-SiO<sub>2</sub>) exhibited higher BET surface area, uniform mesoporosity, better dispersion and stronger MSI compared to the impregnated 20Ni/SiO<sub>2</sub>, highlighting the importance of sol-gel incorporation in texture control. Interestingly, CO<sub>2</sub>-TPD revealed greater CO<sub>2</sub> adsorption ability for impregnated Ni species, whereas H<sub>2</sub>-TPD indicated superior hydrogen dissociation activity for embedded Ni species. Consequently, due to the synergistic contribution of embedded and surface Ni species, the post-impregnated 10Ni/(20Ni-SiO<sub>2</sub>) catalyst achieved 81.6 % CO<sub>2</sub> conversion and 99.5 % CH<sub>4</sub> selectivity at 350 °C, outperforming conventional impregnated and sol-gel catalysts. Stability tests and TPO profiles confirm that the 10Ni/(20Ni-SiO<sub>2</sub>) catalyst maintains efficient performance over 100 h, with only a 5 % decrease in CO<sub>2</sub> conversion, negligible change in CH<sub>4</sub> selectivity, and excellent resistance to coke formation.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"125 ","pages":"Article 102466"},"PeriodicalIF":6.2,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
NH3-based reduction is widely employed for NO control in current research. Compared with NH3, H2 has stronger reductive activity, and introducing H2 for co-denitrification with NH3 is a highly promising strategy. However, the optimal NH3/H2 mixing ratio for NO reduction and the influence of alkali metals on this process remain unclear. Therefore, it is necessary to investigate the optimal NH3/H2 mixing ratio and the effects of alkali metal salts in different occurrence forms (NaCl, Na2CO3, NaAc, Na2SO4) on NO formation and reduction. Based on combustion experiments and reaction kinetics analysis, the effects of alkali metals on NO reduction are explored in this study. The results indicate that H2 addition promotes the formation of NH2 radicals from NH3, thereby significantly enhancing NO reduction. The optimal NO reduction effect (14.14 % improvement) is achieved at an NH3/H2 mixing ratio of 20 %/80 %. Nevertheless, alkali metal salts released during high-alkali coal combustion inhibit the NO reduction efficiency of the NH3/H2 mixture: The addition of NaCl reduces the denitrification efficiency by an average of 10.42 % by consuming H and OH free radicals. Na2CO3 and NaAc accelerate the conversion of NO2 and HNO to NO at medium-low temperatures, and promote NO formation through N2- and HNO-related reactions at high temperatures, reducing the denitrification efficiency by 8.84 % and 8.91 % respectively. Due to its stable chemical properties, the inhibitory effect of Na2SO4 on denitrification efficiency is negligible (only 0.76 %).
{"title":"Effect of alkali metals on NO reduction by NH3/H2 mixtures during high-alkali coal combustion","authors":"Xiayu Zhu , Jing Zhao , Minghui Xu , Jingde Zhao , Heng Cheng , Xiaolin Wei","doi":"10.1016/j.joei.2026.102461","DOIUrl":"10.1016/j.joei.2026.102461","url":null,"abstract":"<div><div>NH<sub>3</sub>-based reduction is widely employed for NO control in current research. Compared with NH<sub>3</sub>, H<sub>2</sub> has stronger reductive activity, and introducing H<sub>2</sub> for co-denitrification with NH<sub>3</sub> is a highly promising strategy. However, the optimal NH<sub>3</sub>/H<sub>2</sub> mixing ratio for NO reduction and the influence of alkali metals on this process remain unclear. Therefore, it is necessary to investigate the optimal NH<sub>3</sub>/H<sub>2</sub> mixing ratio and the effects of alkali metal salts in different occurrence forms (NaCl, Na<sub>2</sub>CO<sub>3</sub>, NaAc, Na<sub>2</sub>SO<sub>4</sub>) on NO formation and reduction. Based on combustion experiments and reaction kinetics analysis, the effects of alkali metals on NO reduction are explored in this study. The results indicate that H<sub>2</sub> addition promotes the formation of NH<sub>2</sub> radicals from NH<sub>3</sub>, thereby significantly enhancing NO reduction. The optimal NO reduction effect (14.14 % improvement) is achieved at an NH<sub>3</sub>/H<sub>2</sub> mixing ratio of 20 %/80 %. Nevertheless, alkali metal salts released during high-alkali coal combustion inhibit the NO reduction efficiency of the NH<sub>3</sub>/H<sub>2</sub> mixture: The addition of NaCl reduces the denitrification efficiency by an average of 10.42 % by consuming H and OH free radicals. Na<sub>2</sub>CO<sub>3</sub> and NaAc accelerate the conversion of NO<sub>2</sub> and HNO to NO at medium-low temperatures, and promote NO formation through N<sub>2</sub>- and HNO-related reactions at high temperatures, reducing the denitrification efficiency by 8.84 % and 8.91 % respectively. Due to its stable chemical properties, the inhibitory effect of Na<sub>2</sub>SO<sub>4</sub> on denitrification efficiency is negligible (only 0.76 %).</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"125 ","pages":"Article 102461"},"PeriodicalIF":6.2,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146188621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2026-01-27DOI: 10.1016/j.joei.2026.102457
Haiqing Sui , Xiang Wang , Wei Cheng , Xinran Wang , Lijun Wang , Zi Ming , Enxiang Ju , Haiping Yang , Hanping Chen
This study proposes an innovative methodology for utilizing the by-products of bio-oils and biochar, generated from biomass carbonization processes at rural power plants in China, to produce bio-slurry. This approach addresses several challenges associated with the standalone application of bio-oils and biochar, drawing significant attention in the field. The char content in the bio-slurry was varied from 0 to 20 wt%, and the hydrogen production during steam gasification of the bio-slurry was investigated. At 500 °C, the yields of H2, CO, and CH4 were 28.44, 70.94, and 41.58 mL/g, respectively. Increasing the temperature markedly enhanced gas production, and at 900 °C the H2, CH4, and CO yields rose to 215.60, 138.88, and 185.25 mL/g, respectively. In addition, steam was found to promote the production of CO and H2, whereas a CO2 atmosphere inhibited the generation of H2 and CH4 at 900 °C. Results showed that the activation energy during the CO2 gasification of the bio-slurry was the lowest under a rapid heating rate, and 800 °C was found to be the optimal pyrolysis temperature for producing biochar with a well-developed pore structure. The experimental gasification of bio-slurry provides quantitative gas-yield data and thermal boundary conditions, which are subsequently used to validate a reduced surrogate kinetic model for predicting bio-slurry gasification behavior under high-temperature conditions. A mixture of toluene and naphthalene was selected as a model compound for bio-oils. The high-temperature steam gasification mechanism of bio-oils was modeled using Chemkin software, leading to the development of a reaction mechanism comprising 26 species and 49 reaction equations. In addition, potential industrial challenges (slurry viscosity, heat-transfer performance, and feeding stability) are considered important considerations for future large-scale applications.
{"title":"Integrated study on gasification of bio-slurry: Experimental validation and computational modeling","authors":"Haiqing Sui , Xiang Wang , Wei Cheng , Xinran Wang , Lijun Wang , Zi Ming , Enxiang Ju , Haiping Yang , Hanping Chen","doi":"10.1016/j.joei.2026.102457","DOIUrl":"10.1016/j.joei.2026.102457","url":null,"abstract":"<div><div>This study proposes an innovative methodology for utilizing the by-products of bio-oils and biochar, generated from biomass carbonization processes at rural power plants in China, to produce bio-slurry. This approach addresses several challenges associated with the standalone application of bio-oils and biochar, drawing significant attention in the field. The char content in the bio-slurry was varied from 0 to 20 wt%, and the hydrogen production during steam gasification of the bio-slurry was investigated. At 500 °C, the yields of H<sub>2</sub>, CO, and CH<sub>4</sub> were 28.44, 70.94, and 41.58 mL/g, respectively. Increasing the temperature markedly enhanced gas production, and at 900 °C the H<sub>2</sub>, CH<sub>4</sub>, and CO yields rose to 215.60, 138.88, and 185.25 mL/g, respectively. In addition, steam was found to promote the production of CO and H<sub>2</sub>, whereas a CO<sub>2</sub> atmosphere inhibited the generation of H<sub>2</sub> and CH<sub>4</sub> at 900 °C. Results showed that the activation energy during the CO<sub>2</sub> gasification of the bio-slurry was the lowest under a rapid heating rate, and 800 °C was found to be the optimal pyrolysis temperature for producing biochar with a well-developed pore structure. The experimental gasification of bio-slurry provides quantitative gas-yield data and thermal boundary conditions, which are subsequently used to validate a reduced surrogate kinetic model for predicting bio-slurry gasification behavior under high-temperature conditions. A mixture of toluene and naphthalene was selected as a model compound for bio-oils. The high-temperature steam gasification mechanism of bio-oils was modeled using Chemkin software, leading to the development of a reaction mechanism comprising 26 species and 49 reaction equations. In addition, potential industrial challenges (slurry viscosity, heat-transfer performance, and feeding stability) are considered important considerations for future large-scale applications.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"125 ","pages":"Article 102457"},"PeriodicalIF":6.2,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146188703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
From both economic and environmental perspectives, the high-value utilization of waste plastics is crucial, particularly through their conversion into carbon nanomaterials via thermochemical technologies. Currently, bimetallic catalysts are widely employed in the pyrolysis of waste plastics to produce carbon nanotubes (CNTs), with Ni-Fe catalysts being the most representative. In this work, to investigate whether increasing the Ni content in Ni-Fe catalysts significantly promotes CNTs growth, waste polyethylene (PE) was used as the carbon source precursor. Three binary metal catalysts with different Ni/Fe molar ratios were prepared by adjusting the Ni/Fe ratio. CNTs were synthesized via one-stage chemical vapor deposition (CVD), and the optimal ratio was selected. Finally, the optimal pyrolysis temperature was explored. The results indicated that Ni/Fe ratios of 1:1 and 3:1 were detrimental to CNTs growth. When the Ni/Fe ratio was 2:1, the bimetallic synergistic effect was optimal, making it more suitable for preparing CNTs with superior morphology and quality. Furthermore, comparative analysis confirms 800 °C as the optimal pyrolysis temperature for CNTs synthesis. The coexistence of Ni-Fe alloy and Fe3C within the catalyst, both acting as active sites, played a crucial synergistic catalytic role in the CNTs growth process. The presence of Ni-Fe alloy enveloping both the base and top ends of the CNTs revealed that their formation follows two concurrent growth modes. This work provided valuable insights for CNTs synthesis via waste plastic pyrolysis and offers novel perspectives on the regulating of bimetallic catalysts.
{"title":"Controlling the Ni/Fe molar ratio and temperature to convert waste plastics into high-quality carbon nanotubes","authors":"Xing Zhang, Liang Yan, Hui Zhou, Bingbing Qiu, Ruiming Fang, Huaqiang Chu","doi":"10.1016/j.joei.2026.102464","DOIUrl":"10.1016/j.joei.2026.102464","url":null,"abstract":"<div><div>From both economic and environmental perspectives, the high-value utilization of waste plastics is crucial, particularly through their conversion into carbon nanomaterials via thermochemical technologies. Currently, bimetallic catalysts are widely employed in the pyrolysis of waste plastics to produce carbon nanotubes (CNTs), with Ni-Fe catalysts being the most representative. In this work, to investigate whether increasing the Ni content in Ni-Fe catalysts significantly promotes CNTs growth, waste polyethylene (PE) was used as the carbon source precursor. Three binary metal catalysts with different Ni/Fe molar ratios were prepared by adjusting the Ni/Fe ratio. CNTs were synthesized via one-stage chemical vapor deposition (CVD), and the optimal ratio was selected. Finally, the optimal pyrolysis temperature was explored. The results indicated that Ni/Fe ratios of 1:1 and 3:1 were detrimental to CNTs growth. When the Ni/Fe ratio was 2:1, the bimetallic synergistic effect was optimal, making it more suitable for preparing CNTs with superior morphology and quality. Furthermore, comparative analysis confirms 800 °C as the optimal pyrolysis temperature for CNTs synthesis. The coexistence of Ni-Fe alloy and Fe<sub>3</sub>C within the catalyst, both acting as active sites, played a crucial synergistic catalytic role in the CNTs growth process. The presence of Ni-Fe alloy enveloping both the base and top ends of the CNTs revealed that their formation follows two concurrent growth modes. This work provided valuable insights for CNTs synthesis via waste plastic pyrolysis and offers novel perspectives on the regulating of bimetallic catalysts.</div></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":"125 ","pages":"Article 102464"},"PeriodicalIF":6.2,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146188706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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