Methane dehydroaromatization(MDA)presents a promising carbon-neutral pathway for benzene,toluene,and xylene(BTX)production,alternative to petroleumderived routes.Elucidating the regulatory mechanisms of Brønsted ...Methane dehydroaromatization(MDA)presents a promising carbon-neutral pathway for benzene,toluene,and xylene(BTX)production,alternative to petroleumderived routes.Elucidating the regulatory mechanisms of Brønsted acid site(BAS)strength on reaction pathways,alongside the spatial proximity effects between BAS and Mo active sites in bifunctional synergy,remains a critical scientific challenge in catalyst design.This study systematically tunes both BAS strength(via isomorphous metal substitution)and Mo-BAS spatial proximity in zeolites,integrating MDA catalytic evaluations with density functional theory(DFT)calculations to dissect their individual contributions.Strongly acidic BAS catalysts(compared to moderately acidic Fe/Ga-substituted counterparts)exhibit superior performance,evidenced by enhanced aromatic yields.Conversely,weakly acidic Bsubstituted zeolites demonstrate optimal mono-/bifunctional synergy,outperforming moderate-acid systems.DFT results reveal that acid strength dictates C−H activation mechanisms by modulating the energy barriers of rate-determining steps.While Al-zeolites deliver the highest activity,B-substituted systems display unique potential for mechanistic investigations.Spatial proximity analysis indicates that micrometer-scale Mo-BAS distances hinder effective synergy due to exceeding electron interaction and mass transfer limits,whereas nanometer-scale proximity enhances activity(via accelerated intermediate transport)and suppresses coke formation.These findings establish a theoretical framework for rationalizing zeolite catalyst optimization through BAS property engineering and spatial control of Mo-BAS cooperation,providing actionable guidelines for designing next-generation MDA catalysts.展开更多
A Brønsted acid-catalyzed peroxidation of 3-hydroxyisoindolinones with hydroperoxides has been established for the first time,which constructsα-amino peroxides bearing a tetrasubstituted stereocenter in good to ...A Brønsted acid-catalyzed peroxidation of 3-hydroxyisoindolinones with hydroperoxides has been established for the first time,which constructsα-amino peroxides bearing a tetrasubstituted stereocenter in good to high yields and enantioselectivities.The transformation uses of environmentally benign solvents,and features operational simplicity,and high atom economy.The synthetic utility was demonstrated with the gram-scale reactions and further transformations of the products.Notably,preliminary bioactivity studies reveal that these valuableα-amino peroxides show potential anticancer activity.展开更多
Directional catalytic transformation of volatile organic compounds(VOCs)into value-added chemicals represents a more sustainable strategy than complete mineralization,as it simultaneously mitigates environmental pollu...Directional catalytic transformation of volatile organic compounds(VOCs)into value-added chemicals represents a more sustainable strategy than complete mineralization,as it simultaneously mitigates environmental pollution and reduces carbon emissions.The primary challenge in achieving multifunctional olefin production from alcohol-type VOCs is the lack of mechanistic clarity,which hinders the targeted synthesis of selective catalysts.Herein,we developed W-Ti hybrid metal oxide catalysts(WTiO_(x))with active Ti-O-W interfaces via a one-step hydrothermal synthesis and demonstrated their effectiveness for isopropanol conversion processes.Remarkably,WTiO_(x)-500 achieved 99.8%isopropanol conversion and 99.3% propylene yield at 140℃,significantly outperforming TiO_(2)(98.4% yield at 180℃)and WO_(3)(90.5% yield at 240℃).WTiO_(x)-500 also displayed higher thermal stability,with isopropanol conversion and propylene yield decreasing by 1.0%and 1.6% after 35 h on-stream reaction.Although impurities(e.g.,CO_(2),HCl,SO_(2))caused partial deactivation of WTiO_(x)-500,oxygen treatment regenerated the catalyst.A series of characterization techniques indicated that the controlled calcination temperature promoted the formation of an optimal Ti-O-Winterface in WTiO_(x)-500 through W substitution into the TiO_(2)lattice and WO_(3)-TiO_(2)surface interaction,where W species effectively tuned the electronic structure.This configuration endowed WTiO_(x)-500 with moderate acidity of BrФnsted(-OH)and Lewis(Ti^(4+)/W^(6+))acid sites,which synergistically facilitated charge transfer between isopropanol and catalyst,accelerated C-O bond cleavage during dehydration.This work provides mechanistic insights into isopropanol dehydration and demonstrates a potential approach for VOC valorization.展开更多
Photocatalytic nitrogen fixation has emerged as a sustainable alternative for ammonia synthesis,playing a crucial role in alleviating energy shortages and environmental pollution.In this study,PbBiO_(2)Br was applied ...Photocatalytic nitrogen fixation has emerged as a sustainable alternative for ammonia synthesis,playing a crucial role in alleviating energy shortages and environmental pollution.In this study,PbBiO_(2)Br was applied to photocatalytic nitrogen fixation for the first time,and its photocatalytic performance was effectively enhanced through Cu doping.The catalyst was synthesized via a simple reduction method,and its morphology,structure,and physicochemical properties were systematically investigated using various characterization techniques and density functional theory calculations.The results revealed that the incorporation of Cu2+partially replaced Pb2+,inducing lattice distortion in PbBiO_(2)Br,promoting the formation of oxygen vacancies,and modifying its electronic band structure.Specifically,Cu doping led to a slight bandgap narrowing,a reduction in work function,and a significant upward shift in the conduction band position.These changes enhanced light absorption,facilitated charge carrier migration and separation,and improved the reduction ability of photogenerated electrons.Moreover,Cu doping promoted N_(2)adsorption and activation.Consequently,the photocatalytic nitrogen fixation performance of Cu-doped PbBiO_(2)Br was significantly enhanced,achieving an optimal nitrogen fixation rate of 293μmol L^(−1)g^(−1)h^(−1),which is 3.6 times higher than that of pristine PbBiO_(2)Br.Additionally,Cu–PbBiO_(2)Br also showed good activity in the photocatalytic degradation of RhB,with a degradation rate 4.6 times higher than that of PbBiO_(2)Br.This work offers new insights into the application of PbBiO_(2)Br in photocatalytic nitrogen fixation and offers valuable guidance for the development of highly efficient nitrogen fixation materials in the future.展开更多
以不同硅/铝摩尔比(简称硅/铝比)的HZSM-5分子筛作为研究对象,通过氨气吸附及程序升温脱附(NH_(3)-TPD)、烷烃吸附及程序升温脱附(Alkane-TPD)、29Si和27Al魔角转动固体核磁共振(29Si&27Al MAS SSNMR)、^(1)H和^(1)H双量子魔角转动...以不同硅/铝摩尔比(简称硅/铝比)的HZSM-5分子筛作为研究对象,通过氨气吸附及程序升温脱附(NH_(3)-TPD)、烷烃吸附及程序升温脱附(Alkane-TPD)、29Si和27Al魔角转动固体核磁共振(29Si&27Al MAS SSNMR)、^(1)H和^(1)H双量子魔角转动固体核磁共振(^(1)H&^(1)H DQ MAS SSNMR)等表征手段,研究了HZSM-5分子筛中Brønsted(B)酸中心的空间邻近性对烷烃分子吸附的特点,同时考察了空间邻近的B酸中心对烷烃单分子裂解选择性的影响。结果表明,随着HZSM-5分子筛硅/铝比的降低,分子筛中B酸中心空间邻近的几率增加,烷烃(丙烷、正丁烷和正戊烷)裂解的反应路径、选择性在邻近的B酸中心都与在孤立的酸中心上不同,显示出协同催化特点。其中,烷烃转化过程中裂解反应增加,脱氢反应减少,中间裂解产物相比于端基裂解产物具有更高的选择性。展开更多
基金Supported by the Science and Technology Major Project of Liaoning Province(2024JH2,1025000892)the Fundamental Research Funds for the Universities of Liaoning Province(LJ232410143051)+1 种基金Liaoning Provincial Science and Technology Program 2023JHl/10400006Shenyang Science and Technology Program(24-213-3-09)。
文摘Methane dehydroaromatization(MDA)presents a promising carbon-neutral pathway for benzene,toluene,and xylene(BTX)production,alternative to petroleumderived routes.Elucidating the regulatory mechanisms of Brønsted acid site(BAS)strength on reaction pathways,alongside the spatial proximity effects between BAS and Mo active sites in bifunctional synergy,remains a critical scientific challenge in catalyst design.This study systematically tunes both BAS strength(via isomorphous metal substitution)and Mo-BAS spatial proximity in zeolites,integrating MDA catalytic evaluations with density functional theory(DFT)calculations to dissect their individual contributions.Strongly acidic BAS catalysts(compared to moderately acidic Fe/Ga-substituted counterparts)exhibit superior performance,evidenced by enhanced aromatic yields.Conversely,weakly acidic Bsubstituted zeolites demonstrate optimal mono-/bifunctional synergy,outperforming moderate-acid systems.DFT results reveal that acid strength dictates C−H activation mechanisms by modulating the energy barriers of rate-determining steps.While Al-zeolites deliver the highest activity,B-substituted systems display unique potential for mechanistic investigations.Spatial proximity analysis indicates that micrometer-scale Mo-BAS distances hinder effective synergy due to exceeding electron interaction and mass transfer limits,whereas nanometer-scale proximity enhances activity(via accelerated intermediate transport)and suppresses coke formation.These findings establish a theoretical framework for rationalizing zeolite catalyst optimization through BAS property engineering and spatial control of Mo-BAS cooperation,providing actionable guidelines for designing next-generation MDA catalysts.
基金supported by the National Natural Science Foundation of China(No.52173044)we thank Dr.Fengchao Wang(Instrumental Analysis and Research Center,Tianjin University of Traditional Chinese Medicine)for providing biological activity testing.
文摘A Brønsted acid-catalyzed peroxidation of 3-hydroxyisoindolinones with hydroperoxides has been established for the first time,which constructsα-amino peroxides bearing a tetrasubstituted stereocenter in good to high yields and enantioselectivities.The transformation uses of environmentally benign solvents,and features operational simplicity,and high atom economy.The synthetic utility was demonstrated with the gram-scale reactions and further transformations of the products.Notably,preliminary bioactivity studies reveal that these valuableα-amino peroxides show potential anticancer activity.
基金supported by the National Natural Science Foundation of China(U23A20120 and 22425601)National Key R&D Program of China(2023YFB3810801)+2 种基金Natural Science Foundation of Hebei Province(B2021208033)Beijing Nova Program(20240484659)R&D Program of Beijing Municipal Education Commission(KZ202210005011).
文摘Directional catalytic transformation of volatile organic compounds(VOCs)into value-added chemicals represents a more sustainable strategy than complete mineralization,as it simultaneously mitigates environmental pollution and reduces carbon emissions.The primary challenge in achieving multifunctional olefin production from alcohol-type VOCs is the lack of mechanistic clarity,which hinders the targeted synthesis of selective catalysts.Herein,we developed W-Ti hybrid metal oxide catalysts(WTiO_(x))with active Ti-O-W interfaces via a one-step hydrothermal synthesis and demonstrated their effectiveness for isopropanol conversion processes.Remarkably,WTiO_(x)-500 achieved 99.8%isopropanol conversion and 99.3% propylene yield at 140℃,significantly outperforming TiO_(2)(98.4% yield at 180℃)and WO_(3)(90.5% yield at 240℃).WTiO_(x)-500 also displayed higher thermal stability,with isopropanol conversion and propylene yield decreasing by 1.0%and 1.6% after 35 h on-stream reaction.Although impurities(e.g.,CO_(2),HCl,SO_(2))caused partial deactivation of WTiO_(x)-500,oxygen treatment regenerated the catalyst.A series of characterization techniques indicated that the controlled calcination temperature promoted the formation of an optimal Ti-O-Winterface in WTiO_(x)-500 through W substitution into the TiO_(2)lattice and WO_(3)-TiO_(2)surface interaction,where W species effectively tuned the electronic structure.This configuration endowed WTiO_(x)-500 with moderate acidity of BrФnsted(-OH)and Lewis(Ti^(4+)/W^(6+))acid sites,which synergistically facilitated charge transfer between isopropanol and catalyst,accelerated C-O bond cleavage during dehydration.This work provides mechanistic insights into isopropanol dehydration and demonstrates a potential approach for VOC valorization.
基金financially supported by the National Natural Science Foundation of China(No.22172144 and 22272151)Key Research and Development Program of Zhejiang Province(2023C03148).
文摘Photocatalytic nitrogen fixation has emerged as a sustainable alternative for ammonia synthesis,playing a crucial role in alleviating energy shortages and environmental pollution.In this study,PbBiO_(2)Br was applied to photocatalytic nitrogen fixation for the first time,and its photocatalytic performance was effectively enhanced through Cu doping.The catalyst was synthesized via a simple reduction method,and its morphology,structure,and physicochemical properties were systematically investigated using various characterization techniques and density functional theory calculations.The results revealed that the incorporation of Cu2+partially replaced Pb2+,inducing lattice distortion in PbBiO_(2)Br,promoting the formation of oxygen vacancies,and modifying its electronic band structure.Specifically,Cu doping led to a slight bandgap narrowing,a reduction in work function,and a significant upward shift in the conduction band position.These changes enhanced light absorption,facilitated charge carrier migration and separation,and improved the reduction ability of photogenerated electrons.Moreover,Cu doping promoted N_(2)adsorption and activation.Consequently,the photocatalytic nitrogen fixation performance of Cu-doped PbBiO_(2)Br was significantly enhanced,achieving an optimal nitrogen fixation rate of 293μmol L^(−1)g^(−1)h^(−1),which is 3.6 times higher than that of pristine PbBiO_(2)Br.Additionally,Cu–PbBiO_(2)Br also showed good activity in the photocatalytic degradation of RhB,with a degradation rate 4.6 times higher than that of PbBiO_(2)Br.This work offers new insights into the application of PbBiO_(2)Br in photocatalytic nitrogen fixation and offers valuable guidance for the development of highly efficient nitrogen fixation materials in the future.
文摘以不同硅/铝摩尔比(简称硅/铝比)的HZSM-5分子筛作为研究对象,通过氨气吸附及程序升温脱附(NH_(3)-TPD)、烷烃吸附及程序升温脱附(Alkane-TPD)、29Si和27Al魔角转动固体核磁共振(29Si&27Al MAS SSNMR)、^(1)H和^(1)H双量子魔角转动固体核磁共振(^(1)H&^(1)H DQ MAS SSNMR)等表征手段,研究了HZSM-5分子筛中Brønsted(B)酸中心的空间邻近性对烷烃分子吸附的特点,同时考察了空间邻近的B酸中心对烷烃单分子裂解选择性的影响。结果表明,随着HZSM-5分子筛硅/铝比的降低,分子筛中B酸中心空间邻近的几率增加,烷烃(丙烷、正丁烷和正戊烷)裂解的反应路径、选择性在邻近的B酸中心都与在孤立的酸中心上不同,显示出协同催化特点。其中,烷烃转化过程中裂解反应增加,脱氢反应减少,中间裂解产物相比于端基裂解产物具有更高的选择性。
