多核Nd-Al双金属配合物对丁二烯的聚合Ⅳ.烷基铝种类的影响

利用多核Ｎｄ－Ａｌ双金属配合物可单独引发双烯聚合的特点，考察了烷基铝种类对丁二烯加聚过程的影响，并与一般混合稀土催化体系进行了比较，烷基铝对活性体催化活性的影响与其用量有关，低ｎ（Ａｌ）ｎ（Ｎｄ）值时，活性次序为：ＡｌＭｅ３，ＡｌＥｔ３，ＨＡｌＢ２〉Ａｌ（Ｃ８Ｈ１７）３〉ＡｌＢｕ３；高ｎ（Ａｌ）／ｎ（Ｎｄ）值时，欠序相反，ＡｌＭｅ３ＡｌｅＴ３，ＨＡｌＢｕ２〈Ａｌ（Ｃ８ｈ１７０３〈ＡｌＢｕ３，烷基铝     

多核Nd-Al双金属配合物对丁二烯的聚合 Ⅳ.烷基铝种类的影响

利用多核Ｎｄ－Ａｌ双金属配合物可单独引发双烯烃聚合的特点，考察了烷基铝种类对丁二烯加聚过程的影响，并与一般混合稀土催化体系进行了比较．烷基铝对活性体催化活性的影响与其用量有关，低ｎ（Ａｌ）／ｎ（Ｎｄ）值时，活性次序为：ＡｌＭｅ３，ＡｌＥｔ３，ＨＡｌＢｕｉ２＞Ａｌ（Ｃ８Ｈ１７）３＞ＡｌＢｕｉ３；高ｎ（Ａｌ）／ｎ（Ｎｄ）值时，活性次序相反：ＡｌＭｅ３，ＡｌＥｔ３，ＨＡｌＢｕｉ２＜Ａｌ（Ｃ８Ｈ１７）３＜ＡｌＢｕｉ３．烷基铝链转移作用强弱次序为：ＨＡｌＢｕｉ２≥ＡｌＥｔ３＞ＡｌＢｕｉ３＞ＡｌＭｅ３＞Ａｌ（Ｃ８Ｈ１７）３．根据聚丁二烯微观结构与其分子量的关系，可将烷基铝对聚丁二烯顺式含量的影响分为３类：（１）ＡｌＥｔ３和Ａｌ（Ｃ８Ｈ１７）３；（２）ＨＡｌ－Ｂｕｉ２和ＡｌＢｕｉ３；（３）ＡｌＭｅ３．所得结果有助于对稀土催化定向聚合过程的深入了解．     

Ω型分子筛脱铝的核磁共振研究

在不同投料比（ＳｉＯ２／Ａｌ２Ｏ３＝１３．８，１９及２１）条件下，合成了三种Ω型分子筛原粉．对投料比为１３．８的原粉样品进行了四种不同方式的脱铝处理，即水热、ＳｉＣｌ４、ＥＤＴＡ和（ＮＨ４）２ＳｉＦ６处理，而形成了系列脱铝Ω型分子筛样品．对原粉及其脱铝样品进行了２９Ｓｉ和２７ＡｌＭＡＳＮＭＲ测试，确定出样品骨架硅铝比和铝在两种晶体学不等价Ｔ位上的占据比率，以探索四种脱铝方法的效果．实验结果与分析表明：在所有样品中，铝原子的占据具有择优Ｂ位的倾向；且铝在ＴＡ与ＴＢ位上的占据比率与合成条件有关；四种处理方式对Ω型分子筛的脱铝效果不尽相同．     

示波库仑滴定法测定水中铝

１引言铝在自然界中分布极广，研究表明过量地摄入铝对人体会产生毒性作用。因此，对水中铝含量的监测已成为环境化学中的重要课题。作者采用示波技术与库仑滴定相结合的示波库仑滴定法测定水中Ａｌ３＋含量。方法以过量８－羟基喹啉沉淀Ａｌ３＋，以电生Ｂｒ２反滴定过量的８－羟基喹啉，用两铂电极示波电位法指示终点。水中少量的Ｃａ２＋、Ｍｇ２＋分别以ＣａＣＯ３、Ｍｇ（ＯＨ）２沉淀分离。操作方便、终点指示灵敏、准确。可检测水中含Ａｌ３＋量～１０６ｍｏｌ／Ｌ。２实验部分２．１仪器与试剂ＳＲ－０７ｌＢ型双踪示波器（江苏杨中…     

多核钕—铝双金属配合物催化丁二烯聚合Ⅴ.甲基铝氧烷的影响

以外添加的方式，考查了甲基铝氧烷ＭＡＯ对多核钕－铝双金属配合物催化丁二烯聚合的影响，并与烷基铝存在下的作用结果相比较。结果表明，ＭＡＯ用量较低时（ｎ（Ａｌ）／ｎ（Ｎｄ）在５－２０之间），即可较烷基铝更大程度提高稀土配合物的催化活性，获得顺式聚丁二烯；ＭＡＯ的链转移作用较烷基铝的低。     

用逸氢热导法测定超细陶瓷粉中游离硅和游离铝

利用游离硅和游离铝与碱溶液作用产生氢气，使它们与ＳｉＣ、Ｓｉ３Ｎ４、ＡｌＮ，ＳｉＯ２以及Ａｌ２Ｏ３等多种硅（铝）化合物分离。     

氯酞菁氯铝的多晶性

制得３种不同晶型的氯酞菁氯铝，并以Ｘ－光粉末衍射（ＸＲＤ）及ＦＴ－ＩＲ表征，比较了各种晶型ＡｌＣｌＰｃｃｌ室温硫化硅橡胶的吸收光谱。讨论了ＡｌＣｌＰｃＣｌ的纯化方法。     

流动注射光度法同时测定铜基合金中的铝和铁

提出了同时测定铜基合金中铝和铁的流动注射分析法。以０．０４ｍｏｌ／ＬＨＣｌ作载液，铬天青Ｓ为显色剂，通过测定６２８ｎｍ处铝、铁两配合物的吸光度之和及铝配合物的吸光度，实现了两组分的同时测定。在优化的实验条件下，检测限：Ａｌ和Ｆｅ分别为１．６９×１０－３和１．７３×１０－３ｍｇ／Ｌ，Ａｌ浓度在０～０．８ｍｇ／Ｌ；Ｆｅ浓度在０～１．０ｍｇ／Ｌ时服从比耳定律。进样频率为６０样／ｈ，所拟方法用于实际样品分析，获得满意结果。     

铝柱联合成皂石上三甲苯转化的研究

以１，３，５－ＴＭＢ和１，２，４－ＴＭＢ转化为模型反应，探讨了铝柱联合成皂石（简称Ａｌ－ＰＳＳ）上表面酸性质的特点。结合不同脱附温度下吡啶吸附量及ＮＨ＿３－ＴＰＤ研究，实验证明，Ａｌ－ＰＳＳ表面具有数目较多，强度较大的酸性中心　和较弱的碱性中心　，与铝柱联天然膨润土（简称Ａｌ－ＣＬＢ）比较，有较高的脱烷基选择性。两种三甲苯在Ａｌ－ＰＳＳ上的转化，不论是单一反应物还是二者混合反应物，其产物分布基本相同，四甲苯在其异构体中含量均高达８０％，说明在本研究反应条件下，两种探针分子以Ａｌ－ＰＳＳ为催化剂进行转化，其产物结构由催化剂结构和性质决定。     

铝—酸性铬蓝K荧光光度法测定微量铝的研究

研究了酸性铬蓝Ｋ（ＡＣＢＫ）荧光光度法测定微量铝的反应。Ａｌ＾３＋与ＡＣＢＫ形成络合物的荧光强度与铝的含量在１×１０＾－８～８×１０＾－６ｍｏｌ／Ｌ范围内呈现良好的线性关系，检测限为４．８×１０＾－９ｍｏｌ／Ｌ，对４×１０＾－８ｍｏｌ／Ｌ铝重复１１次检测其相对标准偏差为４．８％，成功地用于人发及钢样中铝含量的测定。     

沸石结构中骨架铝、非骨架铝固体~(27)Al NMR研究

应用乙酰丙酮络合沸石结构中非骨架铝的性质。建立了固体静态~(27)Al NMR定量测定沸石结构中骨架铝、非骨架铝比率的方法。论证了小角度脉冲和自旋晶格弛豫时间是准确定量的重要条件。同时还考察了水和乙酰丙酮对沸石骨架铝、非骨架铝结构的影响,认为干燥沸石中骨架铝存在于不对称结构中,水分子可以改变其周围电荷分布,提高其结构对称性。非骨架铝存在于极端不对称结构中,其与乙酰丙酮的络合物溶于乙醇溶液中,并具有液体核磁共振行为,因而在计算骨架铝信号强度时须乘上35/9换算因子。     

Hydrothermal Synthesis of Porous Al2O3/Al Metal Ceramics: IV. Synthesis of Composite Porous Ceramics in the Presence of Microporous and Mesoporous Adsorbents

The formation of the structure and properties of mesoporous composite ceramics based on an ASD-1 aluminum powder and commercial adsorbent powders (zeolites and active alumina) was studied. It was found that the mechanism of the formation of contacts between the particles of commercial adsorbents and aluminum is analogous to the mechanism of synthesis of an Al(OH)₃/Al composite. The dissolution of aluminum and the precipitation of the hydroxo complexes of aluminum from solution to the region of interparticle contacts are responsible for this mechanism. The resulting composite ceramics exhibited a polydisperse pore structure and high values of mechanical strength, gas permeability, and thermal conductivity; it can be used as a block adsorbent and catalyst support.     

Photoelectron spectroscopy and Ab initio study of the structure and bonding of Al7N- and Al7N

The electronic and geometrical structures of Al7N- are investigated using photoelectron spectroscopy and ab initio calculations. Photoelectron spectra of Al7N- have been obtained at three photon energies with six resolved spectral features at 193 nm. The spectral features of Al7N- are relatively broad, in particular for the ground state transition, indicating a large geometrical change from the ground state of Al7N- to that of Al7N. The ground state vertical detachment energy is measured to be 2.71 eV, whereas only an upper limit of approximately 1.9 eV can be estimated for the ground state adiabatic detachment energy due to the broad detachment band. Global minimum searches for A7N- and Al7N are performed using several theoretical methods. Vertical electron detachment energies are calculated using three different methods for the lowest energy structure and compared with the experimental data. Calculated results are in excellent agreement with the experimental data. The global minimum structure of Al7N- is found to possess C3v symmetry, which can be viewed as an Al atom capping a face of a N-centered Al6N octahedron. In the ground state of Al7N, however, the capping Al atom is pushed inward with the three adjacent Al-Al distances being stretched outward. Thus, even though Al7N still possesses C3v symmetry, it is better viewed as a N-coordinated by seven Al atoms in a cage-like structure. The chemical bonding in Al7N- is discussed on the basis of molecular orbital and natural bond analysis.     

含镓、锡的铝合金在碱性溶液中的阳极行为

铝的电极电位负,为一1．66V（VS．SHE）,电化当量高（298Ah／g）是一种理想的阳板材料．但是由于铝在空气和水中表面形成一层致密的氧化膜,使其在中性溶液中处于钝化状态．而在酸性或碱性溶液中铝表面氧化膜就会被溶解破坏,与水直接反应,腐蚀中途难以中止．这一直是影响铝作为阳板材料应用和深入研究的障碍,特别是对铝阳极活化溶解机理的研究进展缓慢．虽然目前人们在铝中添加Ga、In、11、Zn、Sn、Mg、Hg等元素,研制出各种铝合金阳极,提高了铝阳极活化性能,但是这些研究本质上仍属于经验性的．到1983年Despic等人提出了“场…     

Chemical selectivity in the remote abstractive chemisorption of ICl on Al(111)

The interaction of ICl and Al(111) involves remote dissociation in its chemisorption process. In remote dissociation, an electron harpoons from an Al(111) surface to an ICl gas molecule to initiate the chemisorption process. We have determined that ICl can chemisorb onto Al(111) by non-activated direct chemisorption, and the sticking probability of this direct channel is 0.65 +/- 0.03. Furthermore, low energy ICl molecules that do not undergo remote dissociation can chemisorb onto Al(111) by precursor-mediated chemisorption. Not only is the interaction of ICl and Al(111) reactive, it is chemically selective. Studies with Auger spectroscopy reveal that the ratio of chlorine atoms to iodine atoms on the Al(111) is 0.32 +/- 0.10 at low (0.042 +/- 0.002) surface coverage. Time-of-flight mass spectrometry studies also show that chlorine atoms are the only species scattered from the surface after ICl interacts with Al(111). These results indicate that iodine-selective abstraction, in which the iodine atom of ICl chemisorbs to the aluminium surface while the chlorine atom is ejected into the gas phase, is the dominant mechanism in this reaction. Iodine-end first collisions are more reactive than chlorine-end first collisions because the lowest unoccupied molecular orbital (LUMO) of ICl is primarily composed of iodine atomic orbitals, and it is the LUMO that interacts with the harpooning electron from the aluminium.     

铝原子团簇Al5、Al5-和Al5+稳定结构的密度泛函理论研究

采用密度泛函理论的四种方法:杂化密度泛函B3LYP与B3PW91、Perdew-Wang91交换与相关泛函WP91PW91、局域自旋密度近似SVWN,研究了A15、Al5-和Al5+团簇的多种可能结构,找到了它们稳定的结构与自旋态,与已有的理论结果作了比较,并计算了Al5-的绝热与垂直电子离解能、Al5的绝热与垂直电离势,同有关的实验数据比较,符合较好.同时对四种密度泛函方法的计算结果作了一些比较与讨论.     

置换法制备核壳结构Cu/Al复合粉末

在以明胶为保护剂、氟离子为络合剂的水溶液中, 采用Al粉直接置换还原铜盐的方法, 实现了纳米Cu在Al粉表面的快速化学沉积, 制备出核壳结构的Cu/Al复合粉末. 提出了置换反应的机理和历程, 探讨了反应的影响因素. 利用SEM, XRD, EDS, BET等测试手段对复合粉末进行了微观测试和表征. 结果表明: Al粉表面连续、均匀包覆了由晶粒大小约20 nm的Cu纳米颗粒组成的壳层.     

Probing the structure and bonding in Al6N- and Al6N by photoelectron spectroscopy and ab initio calculations

The electronic and geometrical structure of a nitrogen-doped Al6- cluster (Al6N-) is investigated using photoelectron spectroscopy and ab initio calculations. Photoelectron spectra of Al6N- have been obtained at three photon energies with seven resolved spectral features. The electron affinity of Al6N has been determined to be 2.58 +/- 0.04 eV. Global minimum structure searches for A6N- and its corresponding neutral form are performed using several theoretical methods. Vertical electron detachment energies, calculated using three different methods for the lowest energy structure and a low-lying isomer, are compared with the experimental data. The ground-state structure of Al6N- is established from the joint experimental and theoretical study to consist of an Al2 dimer bonded to the top of a quasi-planar tetracoordinated N unit, Al4N-, or it can be viewed as a distorted trigonal prism structure with the N atom bonded in one of the prism faces. For neutral Al6N, three low-lying isomers are found to compete for the global minimum, two of which are built from the tetracoordinated Al4N unit. The chemical bonding in Al6N- is discussed on the basis of molecular orbital and natural bond analyses.     

A novel and sensitive method for recognition and indirect determination of Al(III) in biological fluid based on the quenching of resonance Rayleigh scattering intensities of "Al(III)-EV-DNA" complexing system

A novel method for recognition and indirect determination of Al(III) by using biological molecules has been established based on the quenching of RRS intensity. In the weak acidic medium, the reaction of ethyl violet (EV) and DNA would result in great enhancement of RRS intensity. However, the presence of Al(III) would lead to the decrease of the RRS intensity owing to the competition coordination of Al with DNA. The decreased intensity of RRS is directly proportional to the concentration of Al(III) in the range of (0.1-2.5)x10(-6) and (0.30-4.5)x10(-5)M, respectively. The method has high sensitivity and its detection limit (3sigma) is 3.6x10(-8)M. The characteristics of RRS spectra of the system, the optimum conditions of the reaction, and the reaction mechanism have been investigated. The method can recognize Al(III) selectively owing to its strong binding to the phosphate backbone of DNA, and has been applied to the determination of Al(III) concentration in synthetic biological samples with satisfactory results. Therefore, the proposed method is promising as an effective means for selective recognition and sensitive determination in situ of Al(III). Furthermore, this study would contribute to further understanding of the biological significance of Al neurotoxicity.     

Relative importance of hydrolyzed Al(III) species (Al(a), Al(b), and Al(c)) during coagulation with polyaluminum chloride: a case study with the typical micro-polluted source waters

The relative importance of three different Al species, Al(a) (monomeric species, instantaneous reacted species), Al(b) (medium polymer species, reacted less than 120 min), and Al(c) (colloidal or solid species, no reaction), defined by timed complexation reaction rate measured by using ferron reagent in polyaluminum chloride (PACl) was investigated in terms of DOC (dissolved organic carbon), UV(254), and turbidity removal efficiencies. Micro-polluted, typical North China, source waters were used to conduct the experiments. The results show that DOC removal is correlated well to the content of Al(b). Removal of UV(254) is determined by the content of Al(b) and Al(c), particularly Al(c). Turbidity removal is primarily related to the content of Al(c); however, Al(b) could destabilize particles efficiently, and the flocs formed by Al(b) are not as large as those formed by Al(c), which affected the settling efficiency. Unlike the preformed Al(b), the in situ formed Al(b) could remove turbidity more efficiently since Al(c) is the dominant final species formed during coagulation. Al(a) shows a strong ability to react with some unsatisfied coordinate bonds of organic matter to facilitate particle and DOC removal. The distinct coagulation feature of Al(a), Al(b), and Al(c) can be applied to develop tailor-made PACl (with the correct distribution of Al species) to match the characteristics of raw water for optimized coagulation.