Silica-Based and Transition Metal-Based Inorganic-Organic Hybrid Materials—A Comparison

Organically substituted metal alkoxides can be prepared by reaction of the parent alkoxides with complexing organic compounds. The chemical and structural consequences of such substitutions are discussed in this article. Examples are given showing how functional organic moieties, such as polymerizable groups, can be incorporated into sol-gel materials via the complexing ligands. Major structural differences between silica-based and metal-based hybrid materials originate from the different charge/coordination number ratios of silicon and most metals. This results in a high tendency for the molecular building blocks to aggregate. In many cases, metal oxide clusters are formed which are capped by the organic ligands. Such surface-modified clusters are themselves very valuable condensed matter units for materials syntheses.     

催化燃烧去除VOCs污染物的最新进展

催化燃烧是目前最有效的处理挥发性有机物(VOCs)技术之一. 本文从催化剂活性组分、催化剂载体、有效组分颗粒大小、水蒸汽的影响及催化燃烧反应中的积碳等几个方面, 对近年来催化燃烧处理VOCs的研究进行了总结. 分析表明: 贵金属催化剂的研究主要着重于选择有效的载体和双组分贵金属催化剂; 非贵金属催化剂的研究主要集中在高活性的过渡金属复合氧化物、钙钛矿和尖晶石型等催化剂的研制, 还有这些活性组分粒径大小及载体对催化燃烧VOCs反应活性的影响;此外, 在实际应用中,水蒸汽和催化剂积碳失活等问题对催化燃烧VOCs的反应也有很大影响. 本文的评述将为选择合适的催化燃烧技术处理VOCs污染物提供一定参考.     

Capillary Electrophoresis for the Simultaneous Determination of Metals by Using Ethylenediamine Tetraacetic Acid as Complexing Agent and Vancomycin as Complex Selector

A new separation system of capillary electrophoresis for the simultaneous determination of metals by using ethylenediamine tetraacetic acid （EDTA） as complexing agent and employing vancomycin as complex selector was described. The Z-shape cell capillary electrophoresis was used to enhance the sensitivity for the determination of the complexes of Cu（Ⅱ）, Ni（Ⅱ）, Co（Ⅱ） and Fe（Ⅲ） with EDTA. The partial filling method （co-current mode） was used in order to increase the selectivity of the electrophoretic method, meanwhile vancomycin was not present at the detector path during the detection of metal-EDTA complexes. The vancomycin concentration, phosphate concentration and pH of the buffer strongly influenced mobility, resolution and selectivity of the studied analytes. Under the optimal condition, the relative standard deviations （n=5） of the migration time and the peak area were less than 3.14% and 7.35%, respectively. Application of the Z-shape cell capillary electrophoresis method with UV detection and vancomycin loading led to the reliable determination of these metal ions in tap water and the recoveries were 97%-101%. The detection limits based on a signal to noise ratio of 3 ： 1 were found in the range of 2-10 μg·L^-1.     

笼形聚偕胺肟树脂的研究HX／ACAO树脂吸附贵金属

氢卤酸、硝酸、硫酸、磷酸和硼酸处理的笼形聚偕胺肟树脂（ＨＸ／Ａ－ＣＡＯ）对Ａｇ＋和等贵金属离子的吸附能力按如下顺序：ＰｄＣｌ４２－：Ｈ３ＢＯ３／ＡＣＡＯ＞ＢＣＡＯ＞Ｈ３ＰＯ４／ＡＣＡＯ＞ＨＩ／ＡＣＡＯ＞Ｈ２ＳＯ４／ＡＣＡＯ＞ＨＣｌ／ＡＣＡＯ＞ＨＮＯ３／ＡＣＡＯ＞ＨＦ／ＡＣＡＯ．ＩｒＣｌ６２－：ＢＣＡＯ＞Ｈ３ＰＯ４／ＡＣＡＯ＞Ｈ３ＢＯ３／ＡＣＡＯ＞ＨＣｌ／ＡＣＡＯ＞ＨＦ／ＡＣＡＯ＞ＨＩ／ＡＣＡＯ＞Ｈ２ＳＯ４／ＡＣＡＯ≥ＨＮＯ３／ＡＣＡＯ．ＰｔＣｌ６２：ＢＣＡＯ＞Ｈ３ＢＯ３／ＡＣＡＯ＞Ｈ２ＳＯ４／ＡＣＡＯ＞ＨＮＯ３／ＡＣＡＯ＞ＨＣｌ／ＡＣＡＯ＞ＨＦ／ＡＣＡＯ＞Ｈ３ＰＯ４／ＡＣＡＯ＞ＨＩ／ＡＣＡＯ．Ａｇ＋：ＢＣＡＯ＞Ｈ３ＢＯ３／ＡＣＡＯ＞ＨＩ／ＡＣＡＯ＞Ｈ２ＳＯ４／ＡＣＡＯ＞ＨＦ／ＡＣＡＯ＞ＨＣｌ／ＡＣＡＯ＞Ｈ３ＰＯ４／ＡＣＡＯ＞ＨＮＯ３／ＡＣＡＯ．ＡｕＣｌ４－：ＢＣＡＯ＞Ｈ３ＢＯ３＞Ｈ３ＰＯ４／ＡＣＡＯ＞ＨＦ／ＡＣＡＯ＞ＨＣｌ／Ａ－ＣＡＯ＞Ｈ２ＳＯ４／ＡＣＡＯ＞ＨＩ／ＡＣＡＯ＞ＨＮＯ３／Ａ－ＣＡＯ．研究了Ｈ３ＢＯ３／ＡＣＡＯ树脂对Ａｇ＋和离子的吸附动力学，讨论了吸附机理．     

羰基过渡金属异核原子簇(PPh3)2CuFe2Co(CO)8(μ3-S)和(PPh3)3AuFe2Co(CO)7(μ3-S)的合成与表征

本文利用高压法制备HFe₂Co(CO)₉(μ₃-S),作为原料,经脱质子化作用,再分别与(PPh₃)₂Cu(NO₃)和PPh₃AuCl反应,将Ph₃Cu-或Ph₃Au-联接到原始簇合物的中心骨架上,使簇核扩大,得到了组成为(PPh₃)₂CuFe₂Co(CO)₈(μ₃-S)和(PPh₃)₃AuFe₂Co(CO)₇(μ₃-S)的化合物.文中对此两个新化合物进行了IR,UV,¹H和³¹P NMR.元素分析、熔点测定等性质表征,并对(PPh₃)₂CuFe₂Co(CO)₇(μ₃-S)进行了单晶X-射线衍射分析.两个化合物具有类似的中心骨架,在Fe₂和Co原子三角形的上面和下面分别键联着Cu和S,或Au和S原子,构成了三角双锥结构.其中一个簇合物由二个三苯基膦和八个羰基配位,另一个则由三个三苯基膦和七个羰基配位.     

Thermodynamic study of complex formation of benzo-18-crown-6 with K+, Tl+, and Pb2+ in water

H ⁰ and S ⁰ values of the complex formation in water of benzo-18-crown-6 (B18C6) with K⁺, Tl⁺, and Pb²⁺ were determined and compared with those of 18-crown-6. The H⁰ values of B18C6 are negative. The stability in water of the B18C6-metal ion complex at 25°C is governed largely by the magnitude of the H ⁰ value. The B18C6-metal ion complex is less stable in water than the corresponding 18C6-metal ion complex. This is due largely to a less favorable enthalpic contribution of the B18C6-metal ion complex compared with the corresponding 18C6-metal ion complex. The two aromatic ether oxygen atoms of B18C6 are responsible for the larger H ⁰ value of the B18C6-metal ion complex compared with the corresponding 18C6-metal ion complex.     

Metal carbonyl catalysis of carbon monoxide and formate reactions

The water gas shift reaction (CO + H₂O = CO₂+ H₂) is catalyzed by aqueous metal carbonyl systems derived from simple mononuclear carbonyls such as Fe(CO)₅ and M(CO)₆ (M = Cr, Mo, and W) and bases in the 140–200 °C temperature range. The water gas shift reaction in a basic methanol-water solution containing Fe(CO)₅ is first order in [Fe(CO)₅], zero order in [CO], and essentially independent of base concentration and appears to involve an associative mechanism with a metallocarboxylate intermediate [(CO)₄Fe-CO₂H]^–. The water gas shift reactions using M(CO)₆ as catalyst precursors are first order in [M(CO)₆], inverse first order in [CO], and first order in [HCO₂ ^–] and appear to involve a dissociative mechanism with formatometallate intermediates [(CO)₅M-OCHO]^–.The Reppe hydroformylation of ethylene to produce propionaldehyde and 1-propanol in basic solutions containing Fe(CO)₅ occurs at 110–140 °C. This reaction is second order in [Fe(CO)₅], first order in [C₂H₄] up to a saturation pressure >1.5 MPa, and inhibited by [CO]. These experimental results suggest a mechanism where the rate-determining step involves a binuclear iron carbonyl intermediate. The substitution of Et₃N for NaOH as the base facilitates the reduction of propionaldehyde to 1-propanol but results in a slower rate for the overall reaction.The homogeneous photocatalytic decomposition of the formate ion to H₂ and CO₂ in the presence of Cr(CO)₆ appears to be closely related to the water gas shift reaction. The rate of H₂ production from the formate ion exhibits saturation kinetics in the formate ion and is inhibited by added pyridine. The infrared spectra of the catalyst solutions indicate an LCr(CO)₅ intermediate. Photolysis of the Cr(CO)₆/formate system in aqueous methanol in the presence of an aldehyde RCHO (R =n-heptyl,p-tolyl, andp-anisyl) results in catalytic hydrogenation of the aldehyde to the corresponding alcohol RCH₂OH by the formate ion. Detailed kinetic studies onp-tolualdehyde hydrogenation by this method indicates saturation kinetics in formate ion, autoinhibition by thep-tolualdehyde, and a threshold effect for Cr(CO)₆ at concentrations >0.004 mol L^–1. The presence of an aldehyde can interrupt the water gas shift catalytic cycle by interception of an HCr(CO)₅ ^– intermediate by the aldehyde.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1533–1539, September, 1994.     

改性生物凝胶对重金属离子的吸附性能研究

以桔子汁加工残渣为原料,制备钙型和氢型生物凝胶作为吸附剂,用于去除水溶液中的重金属离子.结果表明,上述凝胶在水溶液中稳定性较好,对重金属离子的吸附性能优良.钙型凝胶的吸附选择性顺序为:Fe3 ＞Pb2 ＞Cd2 ＞Zn2 ,饱和吸附容量分别为:Pb2 、Cd2 、Zn2 均为约1.1mmol/g、Fe3 为1.5mmol/g;氢型凝胶的吸附选择性顺序为:Pb2 ＞Zn2 ＞Cd2 .钙型凝胶对Fe3 的吸附行为明显不同于氢型凝胶,钙型凝胶以离子交换机理以及Fe3 与Ca2 之间的共沉淀作用为主;而氢型凝胶对Fe3 的吸附则以离子交换机理为主.     

溶剂化金属原子浸渍法制备的Ni-Ag/γ-Al2O3催化剂的结构表征

应用溶剂化金属原子浸渍法和普通浸渍法制备了三种不同摩尔比的γ－Ａｌ２Ｏ３负载Ｎｉ－Ａｇ双金属催化剂。ＸＲＤ和磁测定结果表明ＳＭＡＩ催化剂中Ｎｉ和Ａｇ的粒度均小于金属相同的ＣＩ催化剂。ＳＭＡＩ催化剂中Ｎｉ和Ａｇ未形成合金，而ＣＩ催化剂中Ｎｉ和Ａｇ形成了合金。     

过渡金属络合物成键本质分析的常用方法

过渡金属络合物中过渡金属与配体间所形成的化学键的成键本质,可以在理论化学基础上,采用定量的方法进行分析。本文重点以铁羰基络合物为例,对常用的分析方法,如自然键轨道方法(NBO)、电荷分解分析(CDA)、分子中的原子(AIM)拓扑分析方法以及ETS和EDA能量分解方法等,在应用中的优缺点进行了分析和评述。借助于这些方法提供的电荷、能量和电子密度等配分项可以深刻认识和理解过渡金属-配体间形成的化学键的成键本质。