The metal–support interactions induced by high-temperature hydrogen reduction have a strong influence on the catalytic performance of ceria-supported Ru catalysts. However, the appearance of the strong metal–support...The metal–support interactions induced by high-temperature hydrogen reduction have a strong influence on the catalytic performance of ceria-supported Ru catalysts. However, the appearance of the strong metal–support interaction leads to covering of the Ru species by Ce suboxides, which is detrimental to the ammonia synthesis reaction that requires metallic species as active sites. In the present work, the interaction between Ru and ceria in the Ru/CeO_(2) catalyst was induced by NaBH_(4) treatment. NaBH_(4) treatment enhanced the fraction of metallic Ru, proportion of Ce^(3+), content of exposed Ru species, and amount of surface oxygen species. As a result, a larger amount of hydrogen species would desorb by the H_(2)-formation pathway and the strength of hydrogen adsorption would be weaker, weakening the inhibition effect of the hydrogen species on ammonia synthesis. In addition, the strong electronic metal–support interaction aids in nitrogen dissociation. Consequently, Ru/CeO_(2) with NaBH_(4) treatment showed higher ammonia synthesis rates than that with only hydrogen reduction.展开更多
The industrial manufacture of ammonia(NH_(3))using Fe-based catalyst works under rigorous conditions.For the goal of carbon-neutrality,it is highly desired to develop advanced catalyst for NH_(3)synthesis at mild cond...The industrial manufacture of ammonia(NH_(3))using Fe-based catalyst works under rigorous conditions.For the goal of carbon-neutrality,it is highly desired to develop advanced catalyst for NH_(3)synthesis at mild conditions to reduce energy consumption and CO_(2)emissions.However,the main challenge of NH_(3)synthesis at mild conditions lies in the dissociation of steady N≡N triple bond.In this work,we report the design of subnanometer Ru clusters(0.8 nm)anchored on the hollow N-doped carbon spheres catalyst(Ru-SNCs),which effectively promotes the NH_(3)synthesis at mild conditions via an associative route.The NH_(3)synthesis rate over Ru-SNCs(0.49%(mass)Ru)reaches up to 11.7 mmol NH_(3)·(g cat)^(-1)·h^(-1) at 400℃ and 3 MPa,which is superior to that of 8.3 mmol NH_(3)·(g cat)^(-1)·h^(-1) over Ru nanoparticle catalyst(1.20%(mass)Ru).Various characterizations show that the N_(2)H_(4)species are the main intermediates for NH_(3)synthesis on Ru-SNCs catalyst.It demonstrates that Ru-SNCs catalyst can follow an associative route for N_(2)activation,which circumvents the direct dissociation of N_(2)and results in highly efficient NH_(3)synthesis at mild conditions.展开更多
Ru-based heterogeneous catalysts have been used in a wide range of important reactions.However,due to the sintering of Ru nanoparticles their practical applications are somewhat restricted.Herein,for the first time we...Ru-based heterogeneous catalysts have been used in a wide range of important reactions.However,due to the sintering of Ru nanoparticles their practical applications are somewhat restricted.Herein,for the first time we report a new and facile strategy to confine Ru and/or Co nanoparticles(NPs) in the channels of N-doped carbon using benzoic acid to guide the deposition location of Ru.The developed catalyst with confined RuCo alloy particles exhibits high resistance against Ru sintering and displays excellent activity and long term stability for NH3 synthesis,achieving an NH3 synthesis rate of up to 18.9 mmol NH_(3) gcat^(-1)h^(-1)at 400℃,which is ca.2.25 times that of the catalyst prepared without confinement(with metal deposited on the support surface).In the latter case,there is an increase of nanoparticle size from 2.52 to 4.25 nm together with ca.48% decrease of NH_(3) synthesis rate after 68 h at 400℃.This study provides a new avenue for simple fabrication of precious-metal-based catalysts that are highly resistant against sintering,specifically suitable for low-temperature synthesis of ammonia with outstanding efficiency.展开更多
The development of effective Ru catalyst for ammonia synthesis is of important practical value and scientific significance because of the wide application of ammonia as a fertilizer and its promising applications in t...The development of effective Ru catalyst for ammonia synthesis is of important practical value and scientific significance because of the wide application of ammonia as a fertilizer and its promising applications in the renewable energy.Generally,ZrO_(2) was regarded as an inferior support for Ru catalyst used in ammonia synthesis.Here we prepare ZrO_(2) with monoclinic phase and carbon species from ZrCl_(4) following the preparation route of UiO-66 as well as ammonia treatment.Owing to the presence of a larger amount of hydrogen adsorption as well as the easier desorption of hydrogen species,the ill effect of hydrogen species on the nitrogen adsorption-desorption and ammonia synthesis can be effectively alleviated.The resulting ZrO_(2)-supported Ru catalyst showed 4 times higher ammonia synthesis activity than the conventional Ru/ZrO_(2) obtained from zirconium nitrate.展开更多
A series of MgAl-layered double oxides(LDO) doped with different rare-earth elements(Y, La, and Ce)were synthesized by the calcination of Mg-Al layered double hydroxides, and Ru, which were used to prepare ammonia syn...A series of MgAl-layered double oxides(LDO) doped with different rare-earth elements(Y, La, and Ce)were synthesized by the calcination of Mg-Al layered double hydroxides, and Ru, which were used to prepare ammonia synthesis catalysts. The as-obtained oxides and catalysts were characterized by XRD,TEM, TPD, TPR and XPS to understand their catalytic performances in ammonia synthesis. The H_2-TPR and HRTEM studies reveal that Ru/Y-LDO catalyst possesses more active Ru metal and small particle size.The XPS demonstrates that the electronic interaction between Y and Ru metals is stronger, which can be tentatively explained by most of Y inserted into the hydrotalcites structure. CO_2-TPD demonstrates that Ru/Y-LDO catalyst shows stronger basic site densities than catalysts doped with Ce and La. Higher activity of the Ru/Y-LDO catalyst can be attributed to smaller particle size, more active metal(Ru) and strong Ru-support interaction.展开更多
The Co/CeO_2 catalysts promoted with Ba or K were prepared to study the effect of promoter on the catalytic performance of ammonia synthesis. The results show that the presence of Ba or K promoter changes the properti...The Co/CeO_2 catalysts promoted with Ba or K were prepared to study the effect of promoter on the catalytic performance of ammonia synthesis. The results show that the presence of Ba or K promoter changes the properties of CeO_2-supported Co catalysts including the surface area, the crystallite size and the morphology of CeO_2, the reduction degree of cobalt species and the adsorption performance of hydrogen and nitrogen. As a consequence, the samples promoted with an appropriate amount of Ba show higher ammonia synthesis rates, while the catalysts with high Ba loading or K promoter all exhibit low catalytic activities.展开更多
In the present study,a series of Ru/ZSM-5 catalysts with different pore-size distributions were prepared and investigated for NH3 synthesis.Our studies indicate that Ru/ZSM-5-Mic with micropore structure exhibits supe...In the present study,a series of Ru/ZSM-5 catalysts with different pore-size distributions were prepared and investigated for NH3 synthesis.Our studies indicate that Ru/ZSM-5-Mic with micropore structure exhibits superior NH3 synthesis rate,which is much higher than those of Ru/ZSM-5-Mac(with macroporous structure)and Ru/ZSM-5-Mes(with mesoporous structure)catalysts.A series of TPD experiments demonstrate that pore-size distributions play an important role in N2 adsorption and activation over Ru/ZSM-5.Moreover,the addition of La significantly promotes the NH3 synthesis performance over Ru/ZSM-5-Mic.Additionally,in situ DRIFTS studies indicate that the main intermediate species over Ru/ZSM-5-Mic are-NH2,and most of the surface hydrogen species desorb following the H2O-formation pathway.展开更多
Ammonia is a key component in fertilizer and the carbon-free hydrogen carrier.Catalytic ammonia synthesis and utilization have played a central role in the development of chemical engineering.The industrial production...Ammonia is a key component in fertilizer and the carbon-free hydrogen carrier.Catalytic ammonia synthesis and utilization have played a central role in the development of chemical engineering.The industrial production of ammonia remains dependent on the energy-and carbon-intensive Haber-Bosch process.A major effort has been devoted to developing robust and efficient catalysts,as well as alternative benign processes.Herein,we detail our endeavors that develop the ammonia synthesis and decomposition catalysts,and utilize the ammonia energy.We firstly discuss the catalysts for ammonia synthesis via dissociative and associative process,and the regulation of catalysts'properties.Then,we review the burgeoning electrocata-lytic nitrogen reduction process,focusing on the enhanced catalytic performances by the regulation of the catalysts and the electrode.Additionally,we provide a novel high-value utilization of ammonia to achieve the"zero-carbon"circular economy.The promising catalysts,reactors,and ammonia energy systems have been discussed in detail.We end this Account that offers future research directions and prospects of ammonia.展开更多
基金financially supported by the National Science Foundation of China (Nos. 21776047, 21825801, 21978051)the Program for Qishan Scholar of Fuzhou University (Grant XRC18033)。
文摘The metal–support interactions induced by high-temperature hydrogen reduction have a strong influence on the catalytic performance of ceria-supported Ru catalysts. However, the appearance of the strong metal–support interaction leads to covering of the Ru species by Ce suboxides, which is detrimental to the ammonia synthesis reaction that requires metallic species as active sites. In the present work, the interaction between Ru and ceria in the Ru/CeO_(2) catalyst was induced by NaBH_(4) treatment. NaBH_(4) treatment enhanced the fraction of metallic Ru, proportion of Ce^(3+), content of exposed Ru species, and amount of surface oxygen species. As a result, a larger amount of hydrogen species would desorb by the H_(2)-formation pathway and the strength of hydrogen adsorption would be weaker, weakening the inhibition effect of the hydrogen species on ammonia synthesis. In addition, the strong electronic metal–support interaction aids in nitrogen dissociation. Consequently, Ru/CeO_(2) with NaBH_(4) treatment showed higher ammonia synthesis rates than that with only hydrogen reduction.
基金the Key Research&Development Program of National Natural Science Foundation of China(22038002)the National Natural Science Foundation of China(21972019,22108037)。
文摘The industrial manufacture of ammonia(NH_(3))using Fe-based catalyst works under rigorous conditions.For the goal of carbon-neutrality,it is highly desired to develop advanced catalyst for NH_(3)synthesis at mild conditions to reduce energy consumption and CO_(2)emissions.However,the main challenge of NH_(3)synthesis at mild conditions lies in the dissociation of steady N≡N triple bond.In this work,we report the design of subnanometer Ru clusters(0.8 nm)anchored on the hollow N-doped carbon spheres catalyst(Ru-SNCs),which effectively promotes the NH_(3)synthesis at mild conditions via an associative route.The NH_(3)synthesis rate over Ru-SNCs(0.49%(mass)Ru)reaches up to 11.7 mmol NH_(3)·(g cat)^(-1)·h^(-1) at 400℃ and 3 MPa,which is superior to that of 8.3 mmol NH_(3)·(g cat)^(-1)·h^(-1) over Ru nanoparticle catalyst(1.20%(mass)Ru).Various characterizations show that the N_(2)H_(4)species are the main intermediates for NH_(3)synthesis on Ru-SNCs catalyst.It demonstrates that Ru-SNCs catalyst can follow an associative route for N_(2)activation,which circumvents the direct dissociation of N_(2)and results in highly efficient NH_(3)synthesis at mild conditions.
基金supported by the National Science Fund for Distinguished Young Scholars of China(21825801)the National Natural Science Foundation of China(21972019)Fujian Outstanding Youth Fund(2019J06011)。
文摘Ru-based heterogeneous catalysts have been used in a wide range of important reactions.However,due to the sintering of Ru nanoparticles their practical applications are somewhat restricted.Herein,for the first time we report a new and facile strategy to confine Ru and/or Co nanoparticles(NPs) in the channels of N-doped carbon using benzoic acid to guide the deposition location of Ru.The developed catalyst with confined RuCo alloy particles exhibits high resistance against Ru sintering and displays excellent activity and long term stability for NH3 synthesis,achieving an NH3 synthesis rate of up to 18.9 mmol NH_(3) gcat^(-1)h^(-1)at 400℃,which is ca.2.25 times that of the catalyst prepared without confinement(with metal deposited on the support surface).In the latter case,there is an increase of nanoparticle size from 2.52 to 4.25 nm together with ca.48% decrease of NH_(3) synthesis rate after 68 h at 400℃.This study provides a new avenue for simple fabrication of precious-metal-based catalysts that are highly resistant against sintering,specifically suitable for low-temperature synthesis of ammonia with outstanding efficiency.
基金supported by the National Natural Science Foundation of China(Nos.22178061,21776047,21825801,and 21978051)。
文摘The development of effective Ru catalyst for ammonia synthesis is of important practical value and scientific significance because of the wide application of ammonia as a fertilizer and its promising applications in the renewable energy.Generally,ZrO_(2) was regarded as an inferior support for Ru catalyst used in ammonia synthesis.Here we prepare ZrO_(2) with monoclinic phase and carbon species from ZrCl_(4) following the preparation route of UiO-66 as well as ammonia treatment.Owing to the presence of a larger amount of hydrogen adsorption as well as the easier desorption of hydrogen species,the ill effect of hydrogen species on the nitrogen adsorption-desorption and ammonia synthesis can be effectively alleviated.The resulting ZrO_(2)-supported Ru catalyst showed 4 times higher ammonia synthesis activity than the conventional Ru/ZrO_(2) obtained from zirconium nitrate.
基金supported by the National Science Fund for Distinguished Young Scholars of China(21825801)the National Natural Science Foundation of China(21972019,21978051).
基金Project supported by the Natural Science Foundation of Fujian Province(2014J01043)the National Natural Science Foundation of China(21203028)PetroChina Innovation Foundation(2016D-5007-0504)
文摘A series of MgAl-layered double oxides(LDO) doped with different rare-earth elements(Y, La, and Ce)were synthesized by the calcination of Mg-Al layered double hydroxides, and Ru, which were used to prepare ammonia synthesis catalysts. The as-obtained oxides and catalysts were characterized by XRD,TEM, TPD, TPR and XPS to understand their catalytic performances in ammonia synthesis. The H_2-TPR and HRTEM studies reveal that Ru/Y-LDO catalyst possesses more active Ru metal and small particle size.The XPS demonstrates that the electronic interaction between Y and Ru metals is stronger, which can be tentatively explained by most of Y inserted into the hydrotalcites structure. CO_2-TPD demonstrates that Ru/Y-LDO catalyst shows stronger basic site densities than catalysts doped with Ce and La. Higher activity of the Ru/Y-LDO catalyst can be attributed to smaller particle size, more active metal(Ru) and strong Ru-support interaction.
基金supported by National Natural Science Foundation of China(21776047,21203028)
文摘The Co/CeO_2 catalysts promoted with Ba or K were prepared to study the effect of promoter on the catalytic performance of ammonia synthesis. The results show that the presence of Ba or K promoter changes the properties of CeO_2-supported Co catalysts including the surface area, the crystallite size and the morphology of CeO_2, the reduction degree of cobalt species and the adsorption performance of hydrogen and nitrogen. As a consequence, the samples promoted with an appropriate amount of Ba show higher ammonia synthesis rates, while the catalysts with high Ba loading or K promoter all exhibit low catalytic activities.
基金Project supported by the National Natural Science Foundation of China(21972019)。
文摘In the present study,a series of Ru/ZSM-5 catalysts with different pore-size distributions were prepared and investigated for NH3 synthesis.Our studies indicate that Ru/ZSM-5-Mic with micropore structure exhibits superior NH3 synthesis rate,which is much higher than those of Ru/ZSM-5-Mac(with macroporous structure)and Ru/ZSM-5-Mes(with mesoporous structure)catalysts.A series of TPD experiments demonstrate that pore-size distributions play an important role in N2 adsorption and activation over Ru/ZSM-5.Moreover,the addition of La significantly promotes the NH3 synthesis performance over Ru/ZSM-5-Mic.Additionally,in situ DRIFTS studies indicate that the main intermediate species over Ru/ZSM-5-Mic are-NH2,and most of the surface hydrogen species desorb following the H2O-formation pathway.
基金support from the Na-tional Natural Science Foundation of China(22038002,21825801,21908028,22178058,21972019,22178061)the National Key RDProgram of China for Renewable Energy and HydrogenTechnology(2020YFB1505604)FujianScience and Technol-ogyMajor Project(202OHZO7009)。
文摘Ammonia is a key component in fertilizer and the carbon-free hydrogen carrier.Catalytic ammonia synthesis and utilization have played a central role in the development of chemical engineering.The industrial production of ammonia remains dependent on the energy-and carbon-intensive Haber-Bosch process.A major effort has been devoted to developing robust and efficient catalysts,as well as alternative benign processes.Herein,we detail our endeavors that develop the ammonia synthesis and decomposition catalysts,and utilize the ammonia energy.We firstly discuss the catalysts for ammonia synthesis via dissociative and associative process,and the regulation of catalysts'properties.Then,we review the burgeoning electrocata-lytic nitrogen reduction process,focusing on the enhanced catalytic performances by the regulation of the catalysts and the electrode.Additionally,we provide a novel high-value utilization of ammonia to achieve the"zero-carbon"circular economy.The promising catalysts,reactors,and ammonia energy systems have been discussed in detail.We end this Account that offers future research directions and prospects of ammonia.
