Metal-based atomically dispersed catalysts have attracted more attention because of their excellent catalytic performance and nearly 100%atom utilization.Therefore,it is very important to comprehensively and systemati...Metal-based atomically dispersed catalysts have attracted more attention because of their excellent catalytic performance and nearly 100%atom utilization.Therefore,it is very important to comprehensively and systematically understand the relationship between catalytic active sites and catalytic performance at atomic scale.Here,we discuss and summarize in detail the key and fundamental factors affecting the active site,and relate them to the catalytic performance.First,we describe the effectiveness of active site design by coordination effects.Then,the role of chemical bonds in the active sites in changing the reaction performance is discussed.In addition,for intermetallic compounds,we explore how the spacing of active atoms affects the catalytic behavior.Moreover,the importance of synergistic effect in catalyst design is further discussed.Finally,the key parameters affecting the catalytic performance at atomic scale are summarized,and the main challenges and development prospects of atomic catalysts in the future are put forward.展开更多
在查明凹凸棒石矿石矿物组成的基础上,系统采集明光市官山采矿场剖面样品,选择典型矿石样品,利用X射线衍射（XRD）、29Si魔角旋转核磁共振（29 Si MAS-NMR）对不同温度煅烧前后凹凸棒石结构研究,结合热重分析以及程序升温凹凸棒石脱水曲...在查明凹凸棒石矿石矿物组成的基础上,系统采集明光市官山采矿场剖面样品,选择典型矿石样品,利用X射线衍射（XRD）、29Si魔角旋转核磁共振（29 Si MAS-NMR）对不同温度煅烧前后凹凸棒石结构研究,结合热重分析以及程序升温凹凸棒石脱水曲线,认识热处理凹凸棒石结构演化规律,为凹凸棒石黏土加工和应用提供理论依据。结果表明：在240℃左右脱除结构中一半的结晶水,晶体结构发生调整,晶体内部孔道出现折叠;在430℃左右脱除另外二分之一结晶水,同时脱出晶体内部结构水和外表面结构水,晶体结构周期性基本破坏;凹凸棒石在500～700℃温度区间热处理后处于非晶化状态,但是c轴方向的部分有序性仍然存在,硅氧四面链尚没有解体;凹凸棒石脱出结构中一半的结晶水后,经过水化后可以恢复到原来的结构状态,超过350℃热处理凹凸棒石脱出更多的结构水后不能通过水化作用恢复到原来的结构状态。展开更多
A metal-organic coordination polymer [Cd（tdc）（bimb）（μ2-H2O）]n （H2tdc = thiophe-ne-2,5-dicarboxylic acid, bimb = 1,4-bis（imidazol-l-yl）-butane） 1 has been hydrothermally synthe- sized and characterized by el...A metal-organic coordination polymer [Cd（tdc）（bimb）（μ2-H2O）]n （H2tdc = thiophe-ne-2,5-dicarboxylic acid, bimb = 1,4-bis（imidazol-l-yl）-butane） 1 has been hydrothermally synthe- sized and characterized by elemental analysis, IR, TG, luminescence spectrum and single-crystal X-ray diffraction. Colorless crystals crystallize in the triclinic system, space group P^-1 with a = 5.8945（3）, b = 10.3129（5）, c = 11.2226（5） A, a = 95.1430（10）,β = 97.9020（10）, γ = 90.5910（10）°, V = 672.84（6） A^3, C11H11CdN2O5S, Mr= 395.68, De = 1.953 g/cm^3, μ（MoKa） = 1.797 mm^-1, F（000） = 390, Z = 2, the final R = 0.0209 and wR = 0.0508 for 2514 observed reflections （I 〉 2σ（I））. The structure of 1 exhibits a two-dimensional layer-like structure.展开更多
基金the National Natural Science Foundation of China(Nos.22171157,21871159,and 21890383)Science and Technology Key Project of Guangdong Province of China(No.2020B010188002)the National Key R&D Program of China(No.2018YFA0702003).
文摘Metal-based atomically dispersed catalysts have attracted more attention because of their excellent catalytic performance and nearly 100%atom utilization.Therefore,it is very important to comprehensively and systematically understand the relationship between catalytic active sites and catalytic performance at atomic scale.Here,we discuss and summarize in detail the key and fundamental factors affecting the active site,and relate them to the catalytic performance.First,we describe the effectiveness of active site design by coordination effects.Then,the role of chemical bonds in the active sites in changing the reaction performance is discussed.In addition,for intermetallic compounds,we explore how the spacing of active atoms affects the catalytic behavior.Moreover,the importance of synergistic effect in catalyst design is further discussed.Finally,the key parameters affecting the catalytic performance at atomic scale are summarized,and the main challenges and development prospects of atomic catalysts in the future are put forward.
文摘在查明凹凸棒石矿石矿物组成的基础上,系统采集明光市官山采矿场剖面样品,选择典型矿石样品,利用X射线衍射（XRD）、29Si魔角旋转核磁共振（29 Si MAS-NMR）对不同温度煅烧前后凹凸棒石结构研究,结合热重分析以及程序升温凹凸棒石脱水曲线,认识热处理凹凸棒石结构演化规律,为凹凸棒石黏土加工和应用提供理论依据。结果表明：在240℃左右脱除结构中一半的结晶水,晶体结构发生调整,晶体内部孔道出现折叠;在430℃左右脱除另外二分之一结晶水,同时脱出晶体内部结构水和外表面结构水,晶体结构周期性基本破坏;凹凸棒石在500～700℃温度区间热处理后处于非晶化状态,但是c轴方向的部分有序性仍然存在,硅氧四面链尚没有解体;凹凸棒石脱出结构中一半的结晶水后,经过水化后可以恢复到原来的结构状态,超过350℃热处理凹凸棒石脱出更多的结构水后不能通过水化作用恢复到原来的结构状态。
基金supported by the Science and Technology Research Projects of the Education Department of Jilin Province (No. 2012.479)
文摘A metal-organic coordination polymer [Cd（tdc）（bimb）（μ2-H2O）]n （H2tdc = thiophe-ne-2,5-dicarboxylic acid, bimb = 1,4-bis（imidazol-l-yl）-butane） 1 has been hydrothermally synthe- sized and characterized by elemental analysis, IR, TG, luminescence spectrum and single-crystal X-ray diffraction. Colorless crystals crystallize in the triclinic system, space group P^-1 with a = 5.8945（3）, b = 10.3129（5）, c = 11.2226（5） A, a = 95.1430（10）,β = 97.9020（10）, γ = 90.5910（10）°, V = 672.84（6） A^3, C11H11CdN2O5S, Mr= 395.68, De = 1.953 g/cm^3, μ（MoKa） = 1.797 mm^-1, F（000） = 390, Z = 2, the final R = 0.0209 and wR = 0.0508 for 2514 observed reflections （I 〉 2σ（I））. The structure of 1 exhibits a two-dimensional layer-like structure.
