Pub Date : 2024-11-15DOI: 10.1016/j.fuel.2024.133684
Faraz Ahmad , Yueli Wen , Muhammad Zeeshan , Bin Wang , Awais Ashraf , Bai Hui , Zheng Cui , Chengda Li , Samia Kausar , Wei Huang
The balance of acid-base property is crucial for the catalytic performance of Side-Chain Alkylation of Toluene with Methanol (SATM). In this work, Na3PO4 modified NaX catalysts with suitable middle base strength and feasible acid-base center distance were prepared by direct solvent-evaporation and exhibited the best styrene selectivity of 45.4 % and the total yield of side chain alkylation products of 71.7 %, respectively at methanol conversion up to 99.9 % in NaX-P(0.075). Notably, the selectivity exhibits surprising stability in the evaluated 15 days, which might owe to the uniform dispersion of active species and constant acid base property. Combined the comprehensive characterizations of solid-state NMR, FTIR, SEM, and XPS, etc., with Density Functional Theory (DFT) calculation results, it is revealed that O-1264 are affected mostly by loading Na+ or both of Na+ and PO43-, which exhibits the least adsorption energy and the highest electronic cloud density in the four kinds of oxygen atoms according to the calculated Bader charge. Therefore, the structure S4 (O-1264) was considered to be the most stable and meet the basicity requirements for SATM.
{"title":"Key function mechanism of Na3PO4-modified NaX for enhanced performance and stability in side chain alkylation of toluene with methanol: DFT and experimental perspectives","authors":"Faraz Ahmad , Yueli Wen , Muhammad Zeeshan , Bin Wang , Awais Ashraf , Bai Hui , Zheng Cui , Chengda Li , Samia Kausar , Wei Huang","doi":"10.1016/j.fuel.2024.133684","DOIUrl":"10.1016/j.fuel.2024.133684","url":null,"abstract":"<div><div>The balance of acid-base property is crucial for the catalytic performance of Side-Chain Alkylation of Toluene with Methanol (SATM). In this work, Na<sub>3</sub>PO<sub>4</sub> modified NaX catalysts with suitable middle base strength and feasible acid-base center distance were prepared by direct solvent-evaporation and exhibited the best styrene selectivity of 45.4 % and the total yield of side chain alkylation products of 71.7 %, respectively at methanol conversion up to 99.9 % in NaX-P<sub>(0.075)</sub>. Notably, the selectivity exhibits surprising stability in the evaluated 15 days, which might owe to the uniform dispersion of active species and constant acid base property. Combined the comprehensive characterizations of solid-state NMR, FTIR, SEM, and XPS, etc., with Density Functional Theory (DFT) calculation results, it is revealed that O-1264 are affected mostly by loading Na<sup>+</sup> or both of Na<sup>+</sup> and PO<sub>4</sub><sup>3-</sup>, which exhibits the least adsorption energy and the highest electronic cloud density in the four kinds of oxygen atoms according to the calculated Bader charge. Therefore, the structure S4 (O-1264) was considered to be the most stable and meet the basicity requirements for SATM.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"382 ","pages":"Article 133684"},"PeriodicalIF":6.7,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654634","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 : 2024-11-15DOI: 10.1016/j.fuel.2024.133718
Wenhua Zhou , Xiaoxuan Li , Chao Chen , Teng Guo , Jianghao Wang , Kaige Wang , Bolong Li , Zhenyu Zhang , Jie Fu
Liquid organic hydrogen carriers (LOHCs) have garnered considerable attention and have undergone extensive studies owing to their high hydrogen storage density and ease of storage and transportation. Research has shown that carbon-supported bimetallic alloys exhibit exceptional performance as catalysts for low-temperature dehydrogenation. Nevertheless, developing high-efficiency carbon support catalysts and revealing the interaction between active metals and support remains challenging but significant. In this work, a cost-effective metal-modified activated carbon (AC) was synthesized and loaded with PdCoO active sites for low-temperature dehydrogenation of dodecahydro-N-ethylcarbazole (12H-NECZ) to produce hydrogen. The results show that: (1) Introducing tin (Sn) into the AC support to form highly dispersed PdCoO/Sn2-C improves the pore distribution and size of the catalyst, promoting the dispersion of active metals on the surface; (2) The interface effect between PdCoOx and Sn-C supports effectively regulates the electron transfer inside the catalyst, enhances the synergistic effect between metals, and reduces electron transfer resistance, thereby improving dehydrogenation catalytic activity. The results show that at 140 °C, 12H-NECZ was completely dehydrogenated after 8 h, with a selectivity of 92.5%, while the palladium loading was only 2.2 wt%. This study provides a suitable method for the targeted design of catalysts by altering the electronic effects of supports.
液态有机氢载体（LOHCs）因其储氢密度高、易于储存和运输而受到广泛关注和研究。研究表明，碳支撑双金属合金作为低温脱氢催化剂表现出卓越的性能。然而，开发高效的碳支撑催化剂并揭示活性金属与支撑物之间的相互作用仍然具有挑战性，但意义重大。在这项工作中，合成了一种具有成本效益的金属改性活性炭（AC），并负载了钯钴氧化物（PdCoO）活性位点，用于十二氢-N-乙基咔唑（12H-NECZ）的低温脱氢制氢。结果表明(1）在 AC 载体中引入锡（Sn）形成高分散的 PdCoO/Sn2-C ，改善了催化剂的孔分布和尺寸，促进了活性金属在表面的分散；（2）PdCoOx 与 Sn-C 载体之间的界面效应有效调节了催化剂内部的电子转移，增强了金属之间的协同效应，降低了电子转移阻力，从而提高了脱氢催化活性。结果表明，在 140 °C 条件下，12H-NECZ 在 8 小时后完全脱氢，选择性达 92.5%，而钯的负载量仅为 2.2 wt%。这项研究为通过改变载体的电子效应有针对性地设计催化剂提供了一种合适的方法。
{"title":"Sn modified carbon support PdCo bimetallic oxide for boosting low-temperature dehydrogenation of dodecahydro-N-ethylcarbazole","authors":"Wenhua Zhou , Xiaoxuan Li , Chao Chen , Teng Guo , Jianghao Wang , Kaige Wang , Bolong Li , Zhenyu Zhang , Jie Fu","doi":"10.1016/j.fuel.2024.133718","DOIUrl":"10.1016/j.fuel.2024.133718","url":null,"abstract":"<div><div>Liquid organic hydrogen carriers (LOHCs) have garnered considerable attention and have undergone extensive studies owing to their high hydrogen storage density and ease of storage and transportation. Research has shown that carbon-supported bimetallic alloys exhibit exceptional performance as catalysts for low-temperature dehydrogenation. Nevertheless, developing high-efficiency carbon support catalysts and revealing the interaction between active metals and support remains challenging but significant. In this work, a cost-effective metal-modified activated carbon (AC) was synthesized and loaded with PdCoO active sites for low-temperature dehydrogenation of dodecahydro-N-ethylcarbazole (12H-NECZ) to produce hydrogen. The results show that: (1) Introducing tin (Sn) into the AC support to form highly dispersed PdCoO/Sn<sub>2</sub>-C improves the pore distribution and size of the catalyst, promoting the dispersion of active metals on the surface; (2) The interface effect between PdCoOx and Sn-C supports effectively regulates the electron transfer inside the catalyst, enhances the synergistic effect between metals, and reduces electron transfer resistance, thereby improving dehydrogenation catalytic activity. The results show that at 140 °C, 12H-NECZ was completely dehydrogenated after 8 h, with a selectivity of 92.5%, while the palladium loading was only 2.2 wt%. This study provides a suitable method for the targeted design of catalysts by altering the electronic effects of supports.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"382 ","pages":"Article 133718"},"PeriodicalIF":6.7,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654648","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 : 2024-11-15DOI: 10.1016/j.fuel.2024.133708
J.Riano Castaneda , S. Kahrobaei , M. Aghajanloo , D. Voskov , R. Farajzadeh
The reduction of temperature caused by Joule-Thomson effect during injection of CO2 in low pressure reservoirs combined with presence of water can lead to formation of hydrates, which in turn reduces rock permeability and hence CO2 injectivity. This paper introduces an empirical model to evaluate impact of hydrate formation on injectivity of CO2 injection wells. Experiments were also conducted to validate the model. The model was then used to simulate injection of CO2 into a multi-layered depleted gas field. The results indicate that operational parameters, particularly CO2 injection rate and temperature, have a large influence on hydrate formation. This is because a higher CO2 injection rate leads to a greater pressure drop within the injection well, potentially triggering conditions conducive to hydrate formation. It is also shown that the dynamics of the competition between the dry-out and temperature fronts play an important role in the final saturation of the hydrate within porous media. For large evaporation rates, the evaporation of water reduces water saturation near wellbore and hence formation of hydrates is limited.
{"title":"Numerical and experimental investigation of impact of CO2 hydrates on rock permeability","authors":"J.Riano Castaneda , S. Kahrobaei , M. Aghajanloo , D. Voskov , R. Farajzadeh","doi":"10.1016/j.fuel.2024.133708","DOIUrl":"10.1016/j.fuel.2024.133708","url":null,"abstract":"<div><div>The reduction of temperature caused by Joule-Thomson effect during injection of CO<sub>2</sub> in low pressure reservoirs combined with presence of water can lead to formation of hydrates, which in turn reduces rock permeability and hence CO<sub>2</sub> injectivity. This paper introduces an empirical model to evaluate impact of hydrate formation on injectivity of CO<sub>2</sub> injection wells. Experiments were also conducted to validate the model. The model was then used to simulate injection of CO<sub>2</sub> into a multi-layered depleted gas field. The results indicate that operational parameters, particularly CO<sub>2</sub> injection rate and temperature, have a large influence on hydrate formation. This is because a higher CO<sub>2</sub> injection rate leads to a greater pressure drop within the injection well, potentially triggering conditions conducive to hydrate formation. It is also shown that the dynamics of the competition between the dry-out and temperature fronts play an important role in the final saturation of the hydrate within porous media. For large evaporation rates, the evaporation of water reduces water saturation near wellbore and hence formation of hydrates is limited.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"381 ","pages":"Article 133708"},"PeriodicalIF":6.7,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.fuel.2024.133577
Tabish Rahman , Bodhisatwa Hazra , Vikram Vishal
Underground coal thermal treatment (UCTT) is an emerging technique for clean energy extraction from coal, which also creates a unique CO2 sink environment in the form of pyrolytic char. In this study, a pathway for cleaner and efficient extraction of energy from coal is proposed. Early coalbed methane (CBM) extraction, application of UCTT followed by CO2 sequestration in pyrolytic char formed during UCTT presents an opportunity to maximize the utility of coal in new energy scenarios. To characterize Jharia coal in terms of its pore size distribution (PSD), pore surface area, pore volume, thermal evolution, CO2 adsorption attributes at low P/T (low-pressure and low-temperature), and surface morphology at different temperatures (30, 150, 300, 450, and 600 °C), a variety of analytical techniques such as low-pressure gas adsorption (LPGA), small angle X-ray scattering (SAXS), mercury intrusion porosimetry (MIP), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were employed. The results show that the quantity of adsorbed CO2 (at low P/T) increased by 138 % for coal subjected to the maximum pyrolysis temperature of 600 °C. The PSD showed significant variations at different pyrolytic temperatures. While the pores did not show large variations when coal was heated up to 300 °C, the micropores increased sharply, while the mesopores and small macropores reduced when heated further. The elevated pyrolytic temperatures resulted in the enlargement and merging of mesopores and small macropores, along with the formation of new pores due to thermal decomposition and release of volatiles. Consequently, this contributed to a significant increase in the volume of macropores, and overall porosity. The increase in the accessibility of pores under the UCTT environment could significantly boost the CO2 storage capacity in coal.
{"title":"Pore structure evolution of Jharia coal for potential underground coal thermal treatment and associated CO2 sequestration","authors":"Tabish Rahman , Bodhisatwa Hazra , Vikram Vishal","doi":"10.1016/j.fuel.2024.133577","DOIUrl":"10.1016/j.fuel.2024.133577","url":null,"abstract":"<div><div>Underground coal thermal treatment (UCTT) is an emerging technique for clean energy extraction from coal, which also creates a unique CO<sub>2</sub> sink environment in the form of pyrolytic char. In this study, a pathway for cleaner and efficient extraction of energy from coal is proposed. Early coalbed methane (CBM) extraction, application of UCTT followed by CO<sub>2</sub> sequestration in pyrolytic char formed during UCTT presents an opportunity to maximize the utility of coal in new energy scenarios. To characterize Jharia coal in terms of its pore size distribution (PSD), pore surface area, pore volume, thermal evolution, CO<sub>2</sub> adsorption attributes at low P/T (low-pressure and low-temperature), and surface morphology at different temperatures (30, 150, 300, 450, and 600 °C), a variety of analytical techniques such as low-pressure gas adsorption (LPGA), small angle X-ray scattering (SAXS), mercury intrusion porosimetry (MIP), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were employed. The results show that the quantity of adsorbed CO<sub>2</sub> (at low P/T) increased by 138 % for coal subjected to the maximum pyrolysis temperature of 600 °C. The PSD showed significant variations at different pyrolytic temperatures. While the pores did not show large variations when coal was heated up to 300 °C, the micropores increased sharply, while the mesopores and small macropores reduced when heated further. The elevated pyrolytic temperatures resulted in the enlargement and merging of mesopores and small macropores, along with the formation of new pores due to thermal decomposition and release of volatiles. Consequently, this contributed to a significant increase in the volume of macropores, and overall porosity. The increase in the accessibility of pores under the UCTT environment could significantly boost the CO<sub>2</sub> storage capacity in coal.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"381 ","pages":"Article 133577"},"PeriodicalIF":6.7,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651880","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 : 2024-11-15DOI: 10.1016/j.fuel.2024.133710
Parthasarathi Deb, Divyansh Singh, Mukund Kumar, Abhishek Paul
The combustion mode known as Reactivity Controlled Compression Ignition (RCCI) has the capability to enhance engine performance and reduce emissions through the utilization of both high-reactivity fuel (HRF) and low-reactivity fuel (LRF). However, the potential of controlling combustion phasing through HRF injection advancement and utilization of a Hydrogen-biodiesel premix remains relatively unexplored. This study investigates the influence of high reactive fuel injection advancement and Hydrogen-biodiesel premix ratio on the combustion, performance, and emissions of an RCCI engine. The HRF injection angles varied from 30°bTDC to 90°bTDC, whereas the premix ratio of Hydrogen and biodiesel varied from 10 % to 70 %. Results showed that the combustion stability improved with increasing HRF injection angle up to 70°bTDC. The hydrogen premix ratio could be raised to 60% in the same condition without hampering engine performance. The brake thermal efficiency was improved by 15 % with a 50 % premix ratio and 70°bTDC HRF injection advancement. At the same operating point, a 73 % reduction in NOX emission, 85 % reduction in soot emission, 61 % reduction in CO emission, and 42 % reduction in UHC emission was also observed concerning base diesel CDC operation. Thus, HRF injection advancement was beneficial in extending the LRF range of the engine.
{"title":"Effect of high reactive fuel injection advancement and hydrogen-biodiesel premix ratio on combustion, performance and emission of a CI engine under RCCI mode","authors":"Parthasarathi Deb, Divyansh Singh, Mukund Kumar, Abhishek Paul","doi":"10.1016/j.fuel.2024.133710","DOIUrl":"10.1016/j.fuel.2024.133710","url":null,"abstract":"<div><div>The combustion mode known as Reactivity Controlled Compression Ignition (RCCI) has the capability to enhance engine performance and reduce emissions through the utilization of both high-reactivity fuel (HRF) and low-reactivity fuel (LRF). However, the potential of controlling combustion phasing through HRF injection advancement and utilization of a Hydrogen-biodiesel premix remains relatively unexplored. This study investigates the influence of high reactive fuel injection advancement and Hydrogen-biodiesel premix ratio on the combustion, performance, and emissions of an RCCI engine. The HRF injection angles varied from 30°bTDC to 90°bTDC, whereas the premix ratio of Hydrogen and biodiesel varied from 10 % to 70 %. Results showed that the combustion stability improved with increasing HRF injection angle up to 70°bTDC. The hydrogen premix ratio could be raised to 60% in the same condition without hampering engine performance. The brake thermal efficiency was improved by 15 % with a 50 % premix ratio and 70°bTDC HRF injection advancement. At the same operating point, a 73 % reduction in NO<sub>X</sub> emission, 85 % reduction in soot emission, 61 % reduction in CO emission, and 42 % reduction in UHC emission was also observed concerning base diesel CDC operation. Thus, HRF injection advancement was beneficial in extending the LRF range of the engine.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"382 ","pages":"Article 133710"},"PeriodicalIF":6.7,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654636","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 : 2024-11-15DOI: 10.1016/j.fuel.2024.133701
Ziyin Liu , Zheng Li , Zhuo Ma , Jiehao Xie , Xiaofang Wen , Xingkun Chen , Yuan Tan , Nian Lei , Wei Lu , Yunjie Ding
Cu-based catalysts are extensively employed in dimethyl oxalate (DMO) hydrogenation, but it is rather challenging to obtain methyl glycolate (MG) over traditional Cu-based catalysts with high selectivity at high DMO conversion. Herein, the physicochemical properties of the typical Cu/SiO2 catalyst and its corresponding catalytic performance toward DMO hydrogenation were tuned by surface modification with a biological template (histidine). On the premise of near-total conversion of DMO, the MG selectivity substantially increased from 15.7 % to 82.9 % when the typical Cu/SiO2 catalyst was modified by 7 wt% histidine, which was fairly impressive among the reported results up to now. Furthermore, comprehensive characterization and kinetic study disclosed the underlying mechanism. After thermal treatment, histidine retains its skeleton framework (imidazole), the emerging Cu–N interaction weakened the Cu-silica interaction, leading to the reduction in percentage of Cu+ and increase in electron density on the Cu/SiO2 catalyst. As a result, the adsorption and activation ability toward MG were obviously suppressed, which was proved as the critical step for selective hydrogenation of DMO toward MG.
{"title":"Histidine-derivate modified Cu/SiO2 catalyst for selective hydrogenation of dimethyl oxalate to methyl glycolate","authors":"Ziyin Liu , Zheng Li , Zhuo Ma , Jiehao Xie , Xiaofang Wen , Xingkun Chen , Yuan Tan , Nian Lei , Wei Lu , Yunjie Ding","doi":"10.1016/j.fuel.2024.133701","DOIUrl":"10.1016/j.fuel.2024.133701","url":null,"abstract":"<div><div>Cu-based catalysts are extensively employed in dimethyl oxalate (DMO) hydrogenation, but it is rather challenging to obtain methyl glycolate (MG) over traditional Cu-based catalysts with high selectivity at high DMO conversion. Herein, the physicochemical properties of the typical Cu/SiO<sub>2</sub> catalyst and its corresponding catalytic performance toward DMO hydrogenation were tuned by surface modification with a biological template (histidine). On the premise of near-total conversion of DMO, the MG selectivity substantially increased from 15.7 % to 82.9 % when the typical Cu/SiO<sub>2</sub> catalyst was modified by 7 wt% histidine, which was fairly impressive among the reported results up to now. Furthermore, comprehensive characterization and kinetic study disclosed the underlying mechanism. After thermal treatment, histidine retains its skeleton framework (imidazole), the emerging Cu–N interaction weakened the Cu-silica interaction, leading to the reduction in percentage of Cu<sup>+</sup> and increase in electron density on the Cu/SiO<sub>2</sub> catalyst. As a result, the adsorption and activation ability toward MG were obviously suppressed, which was proved as the critical step for selective hydrogenation of DMO toward MG.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"381 ","pages":"Article 133701"},"PeriodicalIF":6.7,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651879","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 : 2024-11-15DOI: 10.1016/j.fuel.2024.133740
Weiwei Qian , Xiuyong Shi , Song Li , Shijin Shuai , Jiaojiao Kang
Oxygen content plays a crucial role in influencing the characteristics and formation processes of soot particles. This study explores the effects of varying oxygen levels on the morphology, nanostructure, and formation of soot particles in laminar coflow ethylene-ammonia diffusion flames using a combination of experimental analysis, model development, and numerical simulation. Initially, the impact of oxygen concentration on morphology and nanostructure of particles is examined experimentally. Subsequently, a novel C2H4-NH3-PAHs kinetic model, incorporating cross-reactions between C3A1-A3 and HCN, is developed and validated through parameters such as ignition delay, laminar flame speed, and species concentrations. The new model is then used to analyze the effects of different oxygen concentrations on soot formation and nitrogen-containing PAHs in ethylene-ammonia flames. The findings show that a decrease in oxygen concentration results in an increase in the average diameter of primary particles, a reduction in fringe separation distance and fringe length, and an increase in fringe tortuosity. Additionally, lower oxygen concentrations are found to slightly reduce PAH formation and significantly decrease the surface growth rate via the HACA mechanism, leading to reduced soot formation. Furthermore, the primary nitrogen-containing PAHs identified are 2-benzonitrile and 2-naphthonitrile, followed by pyrrolyl and cyanophenanthrene, with lower oxygen concentrations diminishing the formation of these nitrogen-containing PAHs.
{"title":"Effect of oxygen contents on morphology, nanostructure, and its formation of soot in laminar coflow ethylene-ammonia diffusion flames","authors":"Weiwei Qian , Xiuyong Shi , Song Li , Shijin Shuai , Jiaojiao Kang","doi":"10.1016/j.fuel.2024.133740","DOIUrl":"10.1016/j.fuel.2024.133740","url":null,"abstract":"<div><div>Oxygen content plays a crucial role in influencing the characteristics and formation processes of soot particles. This study explores the effects of varying oxygen levels on the morphology, nanostructure, and formation of soot particles in laminar coflow ethylene-ammonia diffusion flames using a combination of experimental analysis, model development, and numerical simulation. Initially, the impact of oxygen concentration on morphology and nanostructure of particles is examined experimentally. Subsequently, a novel C<sub>2</sub>H<sub>4</sub>-NH<sub>3</sub>-PAHs kinetic model, incorporating cross-reactions between C3A1-A3 and HCN, is developed and validated through parameters such as ignition delay, laminar flame speed, and species concentrations. The new model is then used to analyze the effects of different oxygen concentrations on soot formation and nitrogen-containing PAHs in ethylene-ammonia flames. The findings show that a decrease in oxygen concentration results in an increase in the average diameter of primary particles, a reduction in fringe separation distance and fringe length, and an increase in fringe tortuosity. Additionally, lower oxygen concentrations are found to slightly reduce PAH formation and significantly decrease the surface growth rate via the HACA mechanism, leading to reduced soot formation. Furthermore, the primary nitrogen-containing PAHs identified are 2-benzonitrile and 2-naphthonitrile, followed by pyrrolyl and cyanophenanthrene, with lower oxygen concentrations diminishing the formation of these nitrogen-containing PAHs.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"382 ","pages":"Article 133740"},"PeriodicalIF":6.7,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654577","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 : 2024-11-15DOI: 10.1016/j.fuel.2024.133716
Jiahao Zhang , Xiang Li , Junhui Liu , Junna Liu , Jun Zhang
The development of efficient and cost-effective nano catalysts for the room-temperature hydrolysis of ammonia borane (AB) is crucial for its practical utilization in hydrogen (H2)-based fuel cells. This study specifically investigates the promotional effects on reduced Co3O4 catalysts induced by varying amounts of NaBH4 during the hydrolytic dehydrogenation of ammonia borane. The morphology, structure, surface chemical states and magnetic property of Co3O4 before and after reduction were comprehensively analyzed to elucidate the factors influencing catalytic behavior during hydrolysis. Additionally, DFT calculations were employed to associate the high activity of Co3O4 with two key factors: oxygen vacancies and Co0 species generated after reduction, resulting in VO-rich cobalt/oxide interfaces. Conversely, a slight decrease in catalytic activity was attributed to over-reduction leading to an excess of Co0 species dominating the catalysts. It can be inferred that the oxide phase not only acts as a precursor and support for the reduced nanosized cobalt active component but also serves as a critical catalyst component that enhances water activation.
{"title":"Enhanced impacts of reduction on Co3O4 model catalysts by NaBH4 in the hydrolysis of ammonia borane","authors":"Jiahao Zhang , Xiang Li , Junhui Liu , Junna Liu , Jun Zhang","doi":"10.1016/j.fuel.2024.133716","DOIUrl":"10.1016/j.fuel.2024.133716","url":null,"abstract":"<div><div>The development of efficient and cost-effective nano catalysts for the room-temperature hydrolysis of ammonia borane (AB) is crucial for its practical utilization in hydrogen (H<sub>2</sub>)-based fuel cells. This study specifically investigates the promotional effects on reduced Co<sub>3</sub>O<sub>4</sub> catalysts induced by varying amounts of NaBH<sub>4</sub> during the hydrolytic dehydrogenation of ammonia borane. The morphology, structure, surface chemical states and magnetic property of Co<sub>3</sub>O<sub>4</sub> before and after reduction were comprehensively analyzed to elucidate the factors influencing catalytic behavior during hydrolysis. Additionally, DFT calculations were employed to associate the high activity of Co<sub>3</sub>O<sub>4</sub> with two key factors: oxygen vacancies and Co<sup>0</sup> species generated after reduction, resulting in V<sub>O</sub>-rich cobalt/oxide interfaces. Conversely, a slight decrease in catalytic activity was attributed to over-reduction leading to an excess of Co<sup>0</sup> species dominating the catalysts. It can be inferred that the oxide phase not only acts as a precursor and support for the reduced nanosized cobalt active component but also serves as a critical catalyst component that enhances water activation.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"381 ","pages":"Article 133716"},"PeriodicalIF":6.7,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651881","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 : 2024-11-15DOI: 10.1016/j.fuel.2024.133735
Shiyi Wang , Mingsheng Luo , Zhi Yang , Ziyang Zhang , Wenshuai Yang , Ziyuan Li , Xiaoteng Cui , Lingman Xia , Changke Shao
Using a citrate-assisted liquid phase co-precipitation method, a CuCoAl-LDH composite nanomaterial was successfully synthesized in situ on rGO and applied to alcohol synthesis for the first time. Structural characterization and morphological observations indicate that the hybrid material consists of hexagonal LDH nanosheets that are vertically aligned, crossed and densely distributed on the rGO surface. The graphene support significantly promoted the dispersion of LDH and prevented strong interlayer stacking during LDH crystal growth. After optimization of the Co/Cu ratio, the Cu2Co1/Al2O3/rGO catalyst exhibited a total alcohol selectivity of 60 %, of which 82 % were C2+ alcohols, and no deactivation was observed after 100 h of reaction. The addition of the graphene support significantly reduced the particle size of the Cu-Co alloy on the catalyst surface, and the particles were highly dispersed on both the Al2O3 matrix and the rGO surface. This dispersion facilitated strong interactions between the Cu-Co alloy particles, while the high thermal conductivity of graphene effectively suppressed the formation of hotspots. In addition, the well-ordered three-dimensional nanosheet structure of the LDH precursor provides a large specific surface area and highly uniformly dispersed active centers. This structure not only promotes the formation of bridge adsorption sites with high CO dissociation ability, which balances multiple bonding and bridge CO adsorption, but also significantly increases the probability of CO insertion, thereby enhancing the performance of HAS. This study provides an effective method for the preparation of LDH/rGO composites, demonstrating their broad potential application prospects.
{"title":"Bimetallic Cu-Co catalyst derived from in-situ grown CuCoAl-LDHs on rGO for alcohols synthesis from syngas","authors":"Shiyi Wang , Mingsheng Luo , Zhi Yang , Ziyang Zhang , Wenshuai Yang , Ziyuan Li , Xiaoteng Cui , Lingman Xia , Changke Shao","doi":"10.1016/j.fuel.2024.133735","DOIUrl":"10.1016/j.fuel.2024.133735","url":null,"abstract":"<div><div>Using a citrate-assisted liquid phase co-precipitation method, a CuCoAl-LDH composite nanomaterial was successfully synthesized in situ on rGO and applied to alcohol synthesis for the first time. Structural characterization and morphological observations indicate that the hybrid material consists of hexagonal LDH nanosheets that are vertically aligned, crossed and densely distributed on the rGO surface. The graphene support significantly promoted the dispersion of LDH and prevented strong interlayer stacking during LDH crystal growth. After optimization of the Co/Cu ratio, the Cu<sub>2</sub>Co<sub>1</sub>/Al<sub>2</sub>O<sub>3</sub>/rGO catalyst exhibited a total alcohol selectivity of 60 %, of which 82 % were C<sub>2+</sub> alcohols, and no deactivation was observed after 100 h of reaction. The addition of the graphene support significantly reduced the particle size of the Cu-Co alloy on the catalyst surface, and the particles were highly dispersed on both the Al<sub>2</sub>O<sub>3</sub> matrix and the rGO surface. This dispersion facilitated strong interactions between the Cu-Co alloy particles, while the high thermal conductivity of graphene effectively suppressed the formation of hotspots. In addition, the well-ordered three-dimensional nanosheet structure of the LDH precursor provides a large specific surface area and highly uniformly dispersed active centers. This structure not only promotes the formation of bridge adsorption sites with high CO dissociation ability, which balances multiple bonding and bridge CO adsorption, but also significantly increases the probability of CO insertion, thereby enhancing the performance of HAS. This study provides an effective method for the preparation of LDH/rGO composites, demonstrating their broad potential application prospects.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"381 ","pages":"Article 133735"},"PeriodicalIF":6.7,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652280","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}
Light olefins are the primary building block for the production of petrochemicals and polymers. Light olefins are largely produced from steam/catalytic cracking of naphtha or ethane/propane. Selectivity to light olefins is significantly dependent on the reaction conditions. In this article, several machine learning models are developed and tested to predict the selectivity of ethylene and propylene using seven input features. For this study, a total of eight ML models consisting of adaptive boost, extreme gradient boost, categorical boost, light gradient boost, decision tree with bagging, random forest, k-nearest neighbour, and artificial neural models are developed. The extreme gradient boost model gave the highest prediction accuracy for the ethylene selectivity, while the light gradient boost gave the highest R2 for the propylene selectivity. The SHAP analysis showed the input parameter’s importance ranking for ethylene predictions as temperature > number of carbon atoms > Si/Al ratio > acidity > weight hourly space velocity > effect of diluent > number of hydrogen atoms. The importance ranking of input parameters for propylene selectivity was observed as weight hourly space velocity > acidity > temperature > Si/Al ratio > effect of diluent > number of carbon atoms > number of hydrogen atoms.
{"title":"Development of machine learning model for the prediction of selectivity to light olefins from catalytic cracking of hydrocarbons","authors":"Iradat Hussain Mafat , Sumeet K. Sharma , Dadi Venkata Surya , Chinta Sankar Rao , Uttam Maity , Ashok Barupal , Rakshvir Jasra","doi":"10.1016/j.fuel.2024.133682","DOIUrl":"10.1016/j.fuel.2024.133682","url":null,"abstract":"<div><div>Light olefins are the primary building block for the production of petrochemicals and polymers. Light olefins are largely produced from steam/catalytic cracking of naphtha or ethane/propane. Selectivity to light olefins is significantly dependent on the reaction conditions. In this article, several machine learning models are developed and tested to predict the selectivity of ethylene and propylene using seven input features. For this study, a<!--> <!-->total of eight ML models consisting of adaptive boost, extreme gradient boost, categorical boost, light gradient boost, decision tree with bagging, random forest, k-nearest neighbour, and artificial neural models are developed. The extreme gradient boost model gave the<!--> <!-->highest prediction accuracy for the ethylene selectivity, while the light gradient boost gave the<!--> <!-->highest R<sup>2</sup> for the propylene selectivity. The SHAP analysis showed the input parameter’s importance ranking for ethylene predictions as temperature > number of carbon atoms > Si/Al ratio > acidity > weight hourly space velocity > effect of diluent > number of hydrogen atoms. The importance ranking of input parameters for propylene selectivity was observed as weight hourly space velocity > acidity > temperature > Si/Al ratio > effect of diluent > number of carbon atoms > number of hydrogen atoms.</div></div>","PeriodicalId":325,"journal":{"name":"Fuel","volume":"381 ","pages":"Article 133682"},"PeriodicalIF":6.7,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652281","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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