MgH_(2) is considered one of the most promising hydrogen storage materials because of its safety,high efficiency,high hydrogen storage quantity and low cost characteristics.But some shortcomings are still existed:high...MgH_(2) is considered one of the most promising hydrogen storage materials because of its safety,high efficiency,high hydrogen storage quantity and low cost characteristics.But some shortcomings are still existed:high operating temperature and poor hydrogen absorption dynamics,which limit its application.Porous Ni_(3)ZnC_(0.7)/Ni loaded carbon nanotubes microspheres(NZC/Ni@CNT)is prepared by facile filtration and calcination method.Then the different amount of NZC/Ni@CNT(2.5,5.0 and 7.5 wt%)is added to the MgH_(2) by ball milling.Among the three samples with different amount of NZC/Ni@CNT(2.5,5.0 and 7.5 wt%),the MgH_(2)-5 wt%NZC/Ni@CNT composite exhibits the best hydrogen storage performances.After testing,the MgH_(2)-5 wt%NZC/Ni@CNT begins to release hydrogen at around 110℃ and hydrogen absorption capacity reaches 2.34 wt%H_(2) at 80℃ within 60 min.Moreover,the composite can release about 5.36 wt%H_(2) at 300℃.In addition,hydrogen absorption and desorption activation energies of the MgH_(2)-5 wt%NZC/Ni@CNT composite are reduced to 37.28 and 84.22 KJ/mol H_(2),respectively.The in situ generated Mg_(2)NiH_(4)/Mg_(2)Ni can serve as a"hydrogen pump"that plays the main role in providing more activation sites and hydrogen diffusion channels which promotes H_(2) dissociation during hydrogen absorption process.In addition,the evenly dispersed Zn and MgZn2 in Mg and MgH_(2) could provide sites for Mg/MgH_(2) nucleation and hydrogen diffusion channel.This attempt clearly proved that the bimetallic carbide Ni_(3)ZnC_(0.7) is a effective additive for the hydrogen storage performances modification of MgH_(2),and the facile synthesis of the Ni_(3)ZnC_(0.7)/Ni@CNT can provide directions of better designing high performance carbide catalysts for improving MgH_(2).展开更多
The nature and distribution of Cu species in Cu-SSZ-13 play a vital role in selective catalytic reduction of NO by NH3(NH3-SCR),but existing methods for adjusting the Cu distribution are complex and difficult to contr...The nature and distribution of Cu species in Cu-SSZ-13 play a vital role in selective catalytic reduction of NO by NH3(NH3-SCR),but existing methods for adjusting the Cu distribution are complex and difficult to control.Herein,we report a simple and effective ion-exchange approach to regulate the Cu distribution in the one-pot synthesized Cu-SSZ-13 that possesses sufficient initial Cu species and thus provides a“natural environment”for adjusting Cu distribution precisely.By using this proposed strategy,a series of Cu-SSZ-13x zeolites with different Cu contents and distributions were obtained.It is shown that the dealumination of the as-synthesized Cu-SSZ-13 during the ion-exchange generates abundant vacant sites in the double six-membered-rings of the SSZ-13 zeolite for relocating Cu2+species and thus allows the redistribution of the Cu species.The catalytic results showed that the ion-exchanged Cu-SSZ-13 zeolites exhibit quite different catalytic performance in NH3-SCR reaction but superior to the parent counterpart.The structure–activity relationship analysis indicates that the redistribution of Cu species rather than other factors(e.g.,crystallinity,chemical composition,and porous structure)is responsible for the improved NH3-SCR performance and SO_(2) and H_(2)O resistance.Our work offers an effective method to precisely adjust the Cu distribution in preparing the industrial SCR catalysts.展开更多
The promotion effect of CO in methane dehydroaromatization was investigated using ^13CO probe molecules. By alternative injection of ^13CO to the methane feed, the distribution of ^13CxC6-xH6（x= 0-3） products change...The promotion effect of CO in methane dehydroaromatization was investigated using ^13CO probe molecules. By alternative injection of ^13CO to the methane feed, the distribution of ^13CxC6-xH6（x= 0-3） products changed significantly, confirming the participation of ^13CO in the reaction network. The addition of ^13CO did not change the conversion of CH4 but improved slightly the durability of the methane dehydroaromatization （MDA） reaction, which might be caused by the interaction of the dissociated oxygen species and the deposited carbon species. The ratio of ^13CxC6-xH6 （x = 0-3） varied with the time on stream, which was determined by the competitive reactions of methane decomposition and ^13CO dissociation.展开更多
NizP supported catalysts exhibit high catalytic activities in hydrogenation reaction,of which the particle sizes of Ni_(2)P active phases are the key influential factor.This research focus on the effect of chelators o...NizP supported catalysts exhibit high catalytic activities in hydrogenation reaction,of which the particle sizes of Ni_(2)P active phases are the key influential factor.This research focus on the effect of chelators on the size of Ni_(2)P particles over wrinkle silica nanoparticles(WSNs)by introducing chelating agents EDTA and NTA during impregnation process.The characterization results show that chelators modified cata-lysts possess smaller size of Ni_(2)P particles than the unmodified Ni_(2)P catalysts.Among all the synthesized catalysts,the EDTA modified Ni_(2)PE(1.5)/WSNs catalyst possesses smallest average particle size of Ni_(2)P,only 2.6 nm.Moreover,the Ni_(2)P catalysts with the assistance of EDTA exhibits better catalytic activity than that of NTA under high reaction temperature,which can be ascribed to the strong bonding between EDTA and Ni.And the EDTA modified Ni_(2)PE(1.5)/WSNs catalyst shows highest hydrogenation ability,almost reaching 100%decalin selectivity.展开更多
Herein,a simple synthetic approach is employed for the atomic dispersion of Rh atoms(Rh SAs)over the surface of interconnected Mo_(2)C nanosheets intimately embedded in a three-dimensional Ni_(x)MoO_(y)nanorod arrays(...Herein,a simple synthetic approach is employed for the atomic dispersion of Rh atoms(Rh SAs)over the surface of interconnected Mo_(2)C nanosheets intimately embedded in a three-dimensional Ni_(x)MoO_(y)nanorod arrays(Ni_(x)MoO_(y)NRs)framework;we found that the introduction of both isolated Rh SAs and Ni_(x)MoO_(y)NRs adjusts the electrocatalytic function of the host Mo_(2)C toward the direction of being an advanced and highly stable electrocatalyst for efficient hydrogen evolution at pH-universal conditions.As a result,the proposed catalyst outperforms most recently reported transition metal-based catalysts,and its performance even rivals that of commercial Pt/C,as demonstrated by its ultralow overpotentials of 31.7,109.7,and 95.4 mV at a current density of 10 mA cm^(-2),along with its small Tafel slopes of 42.4,51.2,and 46.8 mV dec^(-1)in acidic,neutral,and alkaline conditions,respectively.In addition,the catalyst shows remarkable long-term stability over all pH values with good maintenance of its catalytic activity and structural characteristics after continuous operation.展开更多
基金supported by research programs of National Natural Science Foundation of China(52101274,51731002)Natural Science Foundation of Shandong Province(No.ZR2020QE011)Youth Top Talent Foundation of Yantai University(2219008).
文摘MgH_(2) is considered one of the most promising hydrogen storage materials because of its safety,high efficiency,high hydrogen storage quantity and low cost characteristics.But some shortcomings are still existed:high operating temperature and poor hydrogen absorption dynamics,which limit its application.Porous Ni_(3)ZnC_(0.7)/Ni loaded carbon nanotubes microspheres(NZC/Ni@CNT)is prepared by facile filtration and calcination method.Then the different amount of NZC/Ni@CNT(2.5,5.0 and 7.5 wt%)is added to the MgH_(2) by ball milling.Among the three samples with different amount of NZC/Ni@CNT(2.5,5.0 and 7.5 wt%),the MgH_(2)-5 wt%NZC/Ni@CNT composite exhibits the best hydrogen storage performances.After testing,the MgH_(2)-5 wt%NZC/Ni@CNT begins to release hydrogen at around 110℃ and hydrogen absorption capacity reaches 2.34 wt%H_(2) at 80℃ within 60 min.Moreover,the composite can release about 5.36 wt%H_(2) at 300℃.In addition,hydrogen absorption and desorption activation energies of the MgH_(2)-5 wt%NZC/Ni@CNT composite are reduced to 37.28 and 84.22 KJ/mol H_(2),respectively.The in situ generated Mg_(2)NiH_(4)/Mg_(2)Ni can serve as a"hydrogen pump"that plays the main role in providing more activation sites and hydrogen diffusion channels which promotes H_(2) dissociation during hydrogen absorption process.In addition,the evenly dispersed Zn and MgZn2 in Mg and MgH_(2) could provide sites for Mg/MgH_(2) nucleation and hydrogen diffusion channel.This attempt clearly proved that the bimetallic carbide Ni_(3)ZnC_(0.7) is a effective additive for the hydrogen storage performances modification of MgH_(2),and the facile synthesis of the Ni_(3)ZnC_(0.7)/Ni@CNT can provide directions of better designing high performance carbide catalysts for improving MgH_(2).
基金supported by the National Natural Science Foundation of China(51871158)the Fundamental Research Program of Shanxi Province(201901D111273)+2 种基金the Innovation and Entrepreneurship Training Program for College Students of Shanxi Province(20210491)Scientific and technological innovation project of colleges and universities in Shanxi Province(2020L0353)the PhD Startup Fund of Taiyuan University of Science and Technology(20182003).
基金supports from National Natural Science Foundation of China(Nos.22178059 and 91934301)Natural Science Foundation of Fujian Province,China(2020J01513)+1 种基金Sinochem Quanzhou Energy Technology Co.,Ltd.(ZHQZKJ-19-F-ZS-0076)Qingyuan Innovation Laboratory(No.00121002),and Fujian Hundred Talent Program.
文摘The nature and distribution of Cu species in Cu-SSZ-13 play a vital role in selective catalytic reduction of NO by NH3(NH3-SCR),but existing methods for adjusting the Cu distribution are complex and difficult to control.Herein,we report a simple and effective ion-exchange approach to regulate the Cu distribution in the one-pot synthesized Cu-SSZ-13 that possesses sufficient initial Cu species and thus provides a“natural environment”for adjusting Cu distribution precisely.By using this proposed strategy,a series of Cu-SSZ-13x zeolites with different Cu contents and distributions were obtained.It is shown that the dealumination of the as-synthesized Cu-SSZ-13 during the ion-exchange generates abundant vacant sites in the double six-membered-rings of the SSZ-13 zeolite for relocating Cu2+species and thus allows the redistribution of the Cu species.The catalytic results showed that the ion-exchanged Cu-SSZ-13 zeolites exhibit quite different catalytic performance in NH3-SCR reaction but superior to the parent counterpart.The structure–activity relationship analysis indicates that the redistribution of Cu species rather than other factors(e.g.,crystallinity,chemical composition,and porous structure)is responsible for the improved NH3-SCR performance and SO_(2) and H_(2)O resistance.Our work offers an effective method to precisely adjust the Cu distribution in preparing the industrial SCR catalysts.
基金supported by the National Basic Research Program of China (2005CB221400)x
文摘The promotion effect of CO in methane dehydroaromatization was investigated using ^13CO probe molecules. By alternative injection of ^13CO to the methane feed, the distribution of ^13CxC6-xH6（x= 0-3） products changed significantly, confirming the participation of ^13CO in the reaction network. The addition of ^13CO did not change the conversion of CH4 but improved slightly the durability of the methane dehydroaromatization （MDA） reaction, which might be caused by the interaction of the dissociated oxygen species and the deposited carbon species. The ratio of ^13CxC6-xH6 （x = 0-3） varied with the time on stream, which was determined by the competitive reactions of methane decomposition and ^13CO dissociation.
基金supported by the National Natural Science Foundation of China(No.21878330)Key Research and Development Program of Ministry of Science and Technology of China(No.2019YFC1907602)Scientific Research and Technology Development Program of China National Petroleum Corporation(2020B-2116).
文摘NizP supported catalysts exhibit high catalytic activities in hydrogenation reaction,of which the particle sizes of Ni_(2)P active phases are the key influential factor.This research focus on the effect of chelators on the size of Ni_(2)P particles over wrinkle silica nanoparticles(WSNs)by introducing chelating agents EDTA and NTA during impregnation process.The characterization results show that chelators modified cata-lysts possess smaller size of Ni_(2)P particles than the unmodified Ni_(2)P catalysts.Among all the synthesized catalysts,the EDTA modified Ni_(2)PE(1.5)/WSNs catalyst possesses smallest average particle size of Ni_(2)P,only 2.6 nm.Moreover,the Ni_(2)P catalysts with the assistance of EDTA exhibits better catalytic activity than that of NTA under high reaction temperature,which can be ascribed to the strong bonding between EDTA and Ni.And the EDTA modified Ni_(2)PE(1.5)/WSNs catalyst shows highest hydrogenation ability,almost reaching 100%decalin selectivity.
基金Supported from the Regional Leading Research Center Program(2019R1A5A8080326)through the National Research Foundation funded by the Ministry of Science and ICT of Republic of Korea.
文摘Herein,a simple synthetic approach is employed for the atomic dispersion of Rh atoms(Rh SAs)over the surface of interconnected Mo_(2)C nanosheets intimately embedded in a three-dimensional Ni_(x)MoO_(y)nanorod arrays(Ni_(x)MoO_(y)NRs)framework;we found that the introduction of both isolated Rh SAs and Ni_(x)MoO_(y)NRs adjusts the electrocatalytic function of the host Mo_(2)C toward the direction of being an advanced and highly stable electrocatalyst for efficient hydrogen evolution at pH-universal conditions.As a result,the proposed catalyst outperforms most recently reported transition metal-based catalysts,and its performance even rivals that of commercial Pt/C,as demonstrated by its ultralow overpotentials of 31.7,109.7,and 95.4 mV at a current density of 10 mA cm^(-2),along with its small Tafel slopes of 42.4,51.2,and 46.8 mV dec^(-1)in acidic,neutral,and alkaline conditions,respectively.In addition,the catalyst shows remarkable long-term stability over all pH values with good maintenance of its catalytic activity and structural characteristics after continuous operation.
