Owing to outstanding hydrophilicity and ionic interaction,layered double hydroxides(LDHs)have emerged as a promising carrier for high performance catalysts.However,the synthesis of new specialized catalytic LDHs for d...Owing to outstanding hydrophilicity and ionic interaction,layered double hydroxides(LDHs)have emerged as a promising carrier for high performance catalysts.However,the synthesis of new specialized catalytic LDHs for degradation of antibiotics still faces some challenges.In this study,a CoFe_(2)O_(4)/MgAl-LDH composite catalyst was synthesized using a hydrothermal coprecipitation method.Comprehensive characterization reveals that the surface of MgAl-LDH is covered with nanometer CoFe_(2)O_(4) particles.The specific surface area of CoFe_(2)O_(4)/MgAl-LDH is 82.84 m^(2)·g^(-)1,which is 2.34 times that of CoFe_(2)O_(4).CoFe_(2)O_(4)/MgAl-LDH has a saturation magnetic strength of 22.24 A·m^(2)·kg^(-1) facilitating efficient solid-liquid separation.The composite catalyst was employed to activate peroxymonosulfate(PMS)for the efficient degradation of tetracycline hydrochloride(TCH).It is found that the catalytic performance of CoFe_(2)O_(4)/MgAl-LDH significantly exceeds that of CoFe_(2)O_(4).The maximum TCH removal reaches 98.2%under the optimal conditions([TCH]=25 mg/L,[PMS]=1.5 mmol/L,CoFe_(2)O_(4)/MgAl-LDH=0.20 g/L,pH 7,and T=25℃).Coexisting ions in the solution,such as SO_(4)^(2-),Cl-,H_(2)PO_(4)^(-),and CO_(3)^(2-),have a negligible effect on catalytic performance.Cyclic tests demonstrate that the catalytic performance of CoFe_(2)O_(4)/MgAl-LDH remains 67.2%after five cycles.Mechanism investigations suggest that O_(2)^(•-)and ^(1)O_(2) produced by CoFe_(2)O_(4)/MgAl-LDH play a critical role in the catalytic degradation.展开更多
Cu-Cr-O nanocomposites that can be used as additives for the catalytic combustion of AP(ammonium perchlorate)-based solid-state propellants were synthesized via a citric acid(CA) complexing approach. Techniques of TG-...Cu-Cr-O nanocomposites that can be used as additives for the catalytic combustion of AP(ammonium perchlorate)-based solid-state propellants were synthesized via a citric acid(CA) complexing approach. Techniques of TG-DTA, XRD as well as TEM were employed to characterize the thermal decomposition procedure, crystal phase, micro-structural morphologies and grain size of the as-synthesized materials respectively. The results show that well-crystallized Cu-Cr-O nanocomposites can be produced after the CA-Cu-Cr precursors are calcined at 500 ℃ for 3 h. Phase composition of the as-obtained Cu-Cr-O nanocomposites depends on the molar ratio of Cu to Cr in the starting reactants. Addition of the as-synthesized Cu-Cr-O nanocomposites as catalysts enhances the burning rate as well as lowers the pressure exponent of the AP-based solid-state propellants considerably. Noticeably, catalyst with a CuCr molar ratio of 0.7 exhibits promising catalytic activity with high burning rate and low pressure exponent at all pressures, due to the effective phase interaction between the spinel CuCr2O4 and delafossite CuCrO2 contained in the as-synthesized Cu-Cr-O nanocomposites.展开更多
Copper-based catalysts have garnered wide attention in the field of electrocatalytic nitrate reduction for ammonia production due to their low hydrogen precipitation activity and high ammonia selectivity.However,they ...Copper-based catalysts have garnered wide attention in the field of electrocatalytic nitrate reduction for ammonia production due to their low hydrogen precipitation activity and high ammonia selectivity.However,they still face challenges pertaining of poor stability and low activity,which hinder their further application.Herein,we present a Cu_(2)O/Cu heterojunction catalyst supported on nitrogen-doped porous carbon for nitrate reduction.High resolution transmission electron microscopy(HRTEM)and X-ray Diffraction(XRD)results confirm the presence of Cu_(2)O/Cu heterojunctions,which serve as an active phase in catalysis.The nitrogen-doped porous carbon as a carrier not only enhances the catalyst’s stability,but also facilitates the exposure and dispersion of active sites.At-1.29 V(vs.RHE),the maximum production rate of ammonia reaches 8.8 mg/(mg·h)with a Faradaic efficiency of 92.8%.This study also elucidates the effect of Cu_(2)O-to-Cu ratio in the heterojunction on catalytic performance,thereby providing valuable insights for designing efficient nitrate reduction catalysts for ammonia production.展开更多
随着全球工业化进程加快,大量二氧化碳被快速地排放到大气中,产生诸多环境问题。CO_(2)作为一种重要的碳资源,通过加氢制备高附加值化学品近年来逐渐受到研究人员广泛关注。芳烃作为一种基本化工原料,传统上主要靠石油裂解和石脑油重整...随着全球工业化进程加快,大量二氧化碳被快速地排放到大气中,产生诸多环境问题。CO_(2)作为一种重要的碳资源,通过加氢制备高附加值化学品近年来逐渐受到研究人员广泛关注。芳烃作为一种基本化工原料,传统上主要靠石油裂解和石脑油重整来生产,通过CO_(2)加氢制备芳烃可以有效减缓对化石能源的过度依赖。但是CO_(2)的惰性强、活化能垒高、C–C偶联精准调控难,使低温CO_(2)加氢制备芳烃的高效催化剂开发存在巨大挑战。目前,采用氧化物–分子筛复合催化剂体系可以将CO_(2)加氢合成甲醇与甲醇制芳烃反应进行耦合,实现CO_(2)加氢直接合成芳烃。本文通过共沉淀法制备了ZnZrO_(x)复合氧化物,并采用等体积浸渍法引入不同过渡金属(Fe、Cu、Co、Ni),随后将其与商用ZSM-5分子筛物理混合制备了M-ZnZrO_(x)/ZSM-5复合催化剂。在275℃、H_(2)/CO_(2)=3、空速为600 m L/(g·h)的反应条件下,采用质量分数为4%的Fe改性的Fe-ZnZrO_(x)与ZSM-5组成的复合催化剂,芳烃选择性高达80.4%,CO_(2)转化率为5.6%,CO选择性为42.2%。进一步探究了ZnZrO_(x)氧化物上Fe含量对复合催化剂性能的影响,发现Fe含量增加有助于提升反应活性与芳烃选择性;当Fe负载量为8%时,芳烃选择性提升至85.0%。这一研究为在温和条件下通过CO_(2)加氢制备芳烃工业催化剂的开发提供了新思路。展开更多
基金University Synergy Innovation Program of Anhui Province(GXXT-2022-083)Science and Technology Plan Project of Wuhu City,China(2023kx12)Anhui Provincial Department of Education New Era Education Project(2023xscx070)。
文摘Owing to outstanding hydrophilicity and ionic interaction,layered double hydroxides(LDHs)have emerged as a promising carrier for high performance catalysts.However,the synthesis of new specialized catalytic LDHs for degradation of antibiotics still faces some challenges.In this study,a CoFe_(2)O_(4)/MgAl-LDH composite catalyst was synthesized using a hydrothermal coprecipitation method.Comprehensive characterization reveals that the surface of MgAl-LDH is covered with nanometer CoFe_(2)O_(4) particles.The specific surface area of CoFe_(2)O_(4)/MgAl-LDH is 82.84 m^(2)·g^(-)1,which is 2.34 times that of CoFe_(2)O_(4).CoFe_(2)O_(4)/MgAl-LDH has a saturation magnetic strength of 22.24 A·m^(2)·kg^(-1) facilitating efficient solid-liquid separation.The composite catalyst was employed to activate peroxymonosulfate(PMS)for the efficient degradation of tetracycline hydrochloride(TCH).It is found that the catalytic performance of CoFe_(2)O_(4)/MgAl-LDH significantly exceeds that of CoFe_(2)O_(4).The maximum TCH removal reaches 98.2%under the optimal conditions([TCH]=25 mg/L,[PMS]=1.5 mmol/L,CoFe_(2)O_(4)/MgAl-LDH=0.20 g/L,pH 7,and T=25℃).Coexisting ions in the solution,such as SO_(4)^(2-),Cl-,H_(2)PO_(4)^(-),and CO_(3)^(2-),have a negligible effect on catalytic performance.Cyclic tests demonstrate that the catalytic performance of CoFe_(2)O_(4)/MgAl-LDH remains 67.2%after five cycles.Mechanism investigations suggest that O_(2)^(•-)and ^(1)O_(2) produced by CoFe_(2)O_(4)/MgAl-LDH play a critical role in the catalytic degradation.
基金Project (2003AA305820) supported by the National High-Tech Research and Development Program of ChinaProject(2006) supported by the Postdoctoral Foundation of Central South University, China
文摘Cu-Cr-O nanocomposites that can be used as additives for the catalytic combustion of AP(ammonium perchlorate)-based solid-state propellants were synthesized via a citric acid(CA) complexing approach. Techniques of TG-DTA, XRD as well as TEM were employed to characterize the thermal decomposition procedure, crystal phase, micro-structural morphologies and grain size of the as-synthesized materials respectively. The results show that well-crystallized Cu-Cr-O nanocomposites can be produced after the CA-Cu-Cr precursors are calcined at 500 ℃ for 3 h. Phase composition of the as-obtained Cu-Cr-O nanocomposites depends on the molar ratio of Cu to Cr in the starting reactants. Addition of the as-synthesized Cu-Cr-O nanocomposites as catalysts enhances the burning rate as well as lowers the pressure exponent of the AP-based solid-state propellants considerably. Noticeably, catalyst with a CuCr molar ratio of 0.7 exhibits promising catalytic activity with high burning rate and low pressure exponent at all pressures, due to the effective phase interaction between the spinel CuCr2O4 and delafossite CuCrO2 contained in the as-synthesized Cu-Cr-O nanocomposites.
基金supported by the Fundamental Research Funds for the Central Universities(DUT22LAB601)the Technology Development Contract of Sinopec(123038).
文摘Copper-based catalysts have garnered wide attention in the field of electrocatalytic nitrate reduction for ammonia production due to their low hydrogen precipitation activity and high ammonia selectivity.However,they still face challenges pertaining of poor stability and low activity,which hinder their further application.Herein,we present a Cu_(2)O/Cu heterojunction catalyst supported on nitrogen-doped porous carbon for nitrate reduction.High resolution transmission electron microscopy(HRTEM)and X-ray Diffraction(XRD)results confirm the presence of Cu_(2)O/Cu heterojunctions,which serve as an active phase in catalysis.The nitrogen-doped porous carbon as a carrier not only enhances the catalyst’s stability,but also facilitates the exposure and dispersion of active sites.At-1.29 V(vs.RHE),the maximum production rate of ammonia reaches 8.8 mg/(mg·h)with a Faradaic efficiency of 92.8%.This study also elucidates the effect of Cu_(2)O-to-Cu ratio in the heterojunction on catalytic performance,thereby providing valuable insights for designing efficient nitrate reduction catalysts for ammonia production.
文摘随着全球工业化进程加快,大量二氧化碳被快速地排放到大气中,产生诸多环境问题。CO_(2)作为一种重要的碳资源,通过加氢制备高附加值化学品近年来逐渐受到研究人员广泛关注。芳烃作为一种基本化工原料,传统上主要靠石油裂解和石脑油重整来生产,通过CO_(2)加氢制备芳烃可以有效减缓对化石能源的过度依赖。但是CO_(2)的惰性强、活化能垒高、C–C偶联精准调控难,使低温CO_(2)加氢制备芳烃的高效催化剂开发存在巨大挑战。目前,采用氧化物–分子筛复合催化剂体系可以将CO_(2)加氢合成甲醇与甲醇制芳烃反应进行耦合,实现CO_(2)加氢直接合成芳烃。本文通过共沉淀法制备了ZnZrO_(x)复合氧化物,并采用等体积浸渍法引入不同过渡金属(Fe、Cu、Co、Ni),随后将其与商用ZSM-5分子筛物理混合制备了M-ZnZrO_(x)/ZSM-5复合催化剂。在275℃、H_(2)/CO_(2)=3、空速为600 m L/(g·h)的反应条件下,采用质量分数为4%的Fe改性的Fe-ZnZrO_(x)与ZSM-5组成的复合催化剂,芳烃选择性高达80.4%,CO_(2)转化率为5.6%,CO选择性为42.2%。进一步探究了ZnZrO_(x)氧化物上Fe含量对复合催化剂性能的影响,发现Fe含量增加有助于提升反应活性与芳烃选择性;当Fe负载量为8%时,芳烃选择性提升至85.0%。这一研究为在温和条件下通过CO_(2)加氢制备芳烃工业催化剂的开发提供了新思路。
