杂原子HMS介孔分子筛的催化脱氢和加氢脱硫性能

ＭＣＭ４１［１］和ＨＭＳ［２］等介孔分子筛对大分子的扩散阻力较小且具有良好的热稳定性,特别是在合成中可以直接将各种杂原子引入骨架,从而调变其催化性能,因此目前介孔分子筛在催化中的应用引起了各国研究者的广泛兴趣．Ｔｉ,Ｚｒ,Ｖ,Ｃｒ,Ｍｎ,Ｃｕ和Ｆｅ...     

ADSORPTION OF 2,4-D ON MODIFIED HYPERCROSSLINKED POLYSTYRENE （NDA-99） AND XAD-4 RESIN

The adsorption behavior of pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous solution has been investigated using a hypercrosslinked polystyrene adsorbent (NDA-99) modified by dimethylamine group as well as a nonionic macroporous adsorbent (XAD-4). The Langmuir and Freundlich isotherm models were employed to fit the experimental data to describe adsorption mechanism. It shows that NDA-99 resin exhibits an adsorption affinity for 2,4-D higher than XAD-4 resin owing to its exceptional micropore structure and the amine group of the hypercrosslinked matrix.Further studies indicate that the hydrogen bonding interaction and the stronger π-π conjugation play a significant role in the course of the adsorption of 2,4-D on NDA-99 resin, which is in agreement with the IR spectroscopic results and the △E values of HOMO (the highest occupied molecular orbit) of adsorbent and LUMO (the lowest unoccupied molecular orbit) of adsorbate calculated from the MINDO/3 model.     

meso-苯基四苯并卟啉锌与芳腈在低温下的电子转移反应

研究了以meso-苯基四苯并卟啉锌作为电子给体,二腈基苯为电子受体分散在聚甲基丙烯酸甲酯中的光子选通光谱烧孔体系的特性.在20K用大功率和长时间的光子选通烧孔实验获得了反应产物的吸收光谱数据,为该体系通过光诱导电子转移反应机理提供了直接证据.     

高比表面积介孔网状氧化镁的制备、表征及对废水中Pb(Ⅱ)的吸附性能和机理

以天然水菱镁矿为原料，通过"煅烧-水化-煅烧"的简单方法制备了高比表面积介孔网状MgO，且实验过程中无须加入任何试剂。系统性研究了氧化镁用量、吸附时间、吸附温度及pH对氧化镁吸附模拟废水中铅离子吸附性能的影响，揭示了吸附机理，并考察了氧化镁对多种离子的吸附效果。结果表明：该氧化镁吸附剂具有188 m²·g^-1的高比表面积和0.85 cm³·g^-1的高孔体积，平均孔径为12.33 nm，其吸附动力学和等温线数据与伪二级模型和Langmuir模型高度吻合，表明重金属离子在氧化镁上为单层化学吸附。MgO介孔网状结构表现出对Pb（Ⅱ）的高吸附性能，最大吸附量为7 431.5 mg·g^-1，该数值远高于其他报道的基于MgO吸附剂的数值，铅去除率高达99.8%以上。介孔网状MgO的吸附机理主要是羟基官能团以及Mg（Ⅱ）与MgO表面重金属离子之间的离子交换所致。另外，该氧化镁可同时吸附多种离子，对Cd、Cr、Ni、As、Co、P、Se、Be、Bi、Cu、Fe、Mn、V、Zn、Al离子均具有优异的吸附性能。     

本征值有限元近似的一个抽象误差估计式

设T：LZ（fi）MLZ（fi）是自共轭全连续算子，SgCLZ（fi）是分片。次有限元空间，几：LZ、St是有限秩自共轭算子，IITh-Tllo、0（h、0）．考虑本征值问题：及其近似用（·，·）和DD·D【。·分别表示h（m中内积和范数·ID·卜F表示w认｝（m中范数，简记D卜队。为D卜卜·因为T自共轭全连续，所以它有可数无穷个本征值h，人，...人，...．其相应的本征函数（2丹构成完全标准直交系，所以VZELZ（m设几的本征值为A。l，汕。，...，汕n，相应的本征函数为如山，卜则。二1·不失一般性，可EitL。设tik一大干二＞，E是到Ah对应的本…     

Synthesis and Characterization of Titanium-doped Ordered Mesoporous Alumina

Titanium-doped ordered mesoporous alumina with specific structural properties has been prepared by the evaporation induced self-assembly sol-gel method. The results show that the doped titanium helps to stabilize the ordered mesoporous alumina material without influencing the ordered mesoporosity. The textural properties of the obtained sample are related to the amount of doped titanium. When the molar ratio of aluminum to titanium(n(Al)/n(Ti)) is controlled as 10.2, the titanium-doped ordered mesoporous alumina exhibits high surface area(up to 218 m2 g-1), large pore volume(0.42 cm3 g-1) and narrow pore diameter(6.1 nm) after treating at 900 ℃, showing high thermal stability. Moreover, the obtained sample calcined at 900 ℃ still maintains ordered mesoporous structure and exhibits high thermal stability.     

巧变形,妙解题

"希望杯"全国数学邀请赛试题越来越深受高中学生的亲眯,其原因就在于"希望杯"赛题的考查内容广而新,题型灵活多变、充满生机与活力,解题方法丰富多彩、别具一格.本文介绍一道2012年"希望杯"高二赛题的解法,供参考.     

富羧酸基团的共轭微孔聚合物:结构单元对孔隙和气体吸附性能的影响

Polar groups in the skeletons of conjugated microporous polymers (CMPs) play an important role in determining their porosity and gas sorption performance. Understanding the effect of the polar group on the properties of CMPs is essential for further advances in this field. To address this fundamental issue, we used benzene, the simplest aromatic system, as a monomer for the construction of two novel CMPs with multi-carboxylic acid groups in their skeletons (CMP-COOH@1 and CMP-COOH@2). We then explored the profound effect the amount of free carboxylic acid in each polymer had on their porosity, isosteric heat, gas adsorption, and gas selectivity. CMP-COOH@1 and CMP-COOH@2 showed Brunauer-Emmett-Teller (BET) surface areas of 835 and 765 m²·g^-1, respectively, displaying high potential for carbon dioxide storage applications. CMP-COOH@1 and CMP-COOH@2 exhibited CO₂ capture capabilities of 2.17 and 2.63 mmol·g^-1 (at 273 K and 1.05 × 10⁵ Pa), respectively, which were higher than those of their counterpart polymers, CMP-1 and CMP-2, which showed CO₂ capture capabilities of 1.66 and 2.28 mmol·g^-1, respectively. Our results revealed that increasing the number of carboxylic acid groups in polymers could improve their adsorption capacity and selectivity.