F-T合成Fe/Cu/K/Al2O3催化剂的结构性质、还原及碳化行为

采用连续共沉淀与喷雾干燥成型技术相结合的方法制备了微球状Fe/Cu/K/Al2O3催化剂, 结合TG、N2物理吸附、XRD、H2-TPR、CO-TPR、Mossbauer谱等表征手段, 研究焙烧温度对Fischer-Tropshc (F-T)合成铁基催化剂的结构性质、还原行为和碳化行为的影响. 结果表明, 较高的焙烧温度有利于碳酸盐的分解和结晶水的脱除, 促进了催化剂的还原. 随着焙烧温度的进一步升高, 催化剂的比表面积减小, 平均孔径增大, α-Fe2O3晶粒的粒径增大, 催化剂中金属与载体的相互作用增强, 从而削弱了CuO、K2O助剂的作用, 严重抑制了催化剂的还原和碳化.     

铈锆比对低贵金属Pt＋Rh/Ce0.3＋xZr0.6－xY0.1O1.95＋Al2O3三效催化剂性能的影响

用共沉淀法制得一系列铈锆比不同的Ce_0.3＋xZr_0.6－xY_0.1O_1.95储氧材料, 并用于制备了一系列低贵金属Pt＋Rh/Ce_0.3＋xZr_0.6－xY_0.1O_1.95＋Al₂O₃三效催化剂. 用比表面、程序升温还原以及X射线衍射对该系列催化剂进行表征, 结果发现, 催化剂的活性与催化剂中贵金属的还原性能密切相关, 低铈储氧材料比高铈储氧材料更有利于促进贵金属还原, 因而含低铈储氧材料催化剂的活性明显优于含高铈储氧材料催化剂的活性, Pt＋Rh/Ce_0.35Zr_0.55Y_0.1O_1.95＋Al₂O₃的活性最佳, 对HC, CO和NO的起燃温度最低分别为: 235, 175, 200 ℃. 样品经1000 ℃水热老化之后, 贵金属Pt被烧结而发生迁移, 使得催化剂的活性及还原性能变差, 含低铈材料的催化剂的抗老化性能优于含高铈材料的催化剂, 其中Pt＋Rh/Ce_0.35Zr_0.55Y_0.1O_1.95＋Al₂O₃的抗老化性能最好.     

CVD Reactions of TiCl4 with Ammonia： a Quantum Chemical Study

Based on density functional calculations, the mechanism and the energetic course of the chemical vapor deposition （CVD） reaction of TiCl4 with NH3 were studied at the level of B3LYP with 6-311g（d） basis set. Furthermore, the polymerization processes of dimerization, trimerization and tetramerization were investigated. The calculation results indicate that the formation of polymers is favored at the elimination reaction. On the basis of the calculated energetics, a possible mechanism of the reduction reaction has been proposed.     

富氧条件下乙炔选择催化还原NOx

Acetylene as a reducing agent of metal exchanged HY catalysts, for selective catalytic reduction of NO in the reaction system of 0.16% NO, 0 （C2H2-SCR） was investigated over a series 08% C2H2, and 9.95% O2 （volume percent） in He. 75% of NO conversion to N2 with hydrocarbon efficiency about 1.5 was achieved over a Ce-HY catalyst around 300 ℃. The NO removal level was comparable with that of selective catalytic reduction of NOx by C3H6 reported in literatures, although only one third of the reducing agent in carbon moles was used in the C2H2-SCR of NO. The protons in zeolite were crucial to the C2H2-SCR of NO, and the performance of HY in the reaction was significantly promoted by cerium incorporation into the zeolite. NO2 was proposed to be the intermediate of NO reduction to N2, and the oxidation of NO to NO2 was rate-determining step of the C2H2-SCR of NO over Ce-HY. The suggestion was well supported by the results of the NO oxidation with O2, and the C2H2 consumption under the conditions in the presence or absence of NO.     

添加Ag对Cu／γ—Al2O3催化剂性能的影响

运用ＢＥＴ、ＸＲＤ、ＴＰＲ及苯和丙酮氧化活性测定等方面研究了Ｃｕ／γ－Ａｌ２Ｏ３和Ｃｕ－Ａｇ／γ－Ａｌ２Ｏ３催化剂的还原性能和有机物的催化活性，结果表明，不同金属负载量的Ｃｕ／γ－Ａｌ２Ｏ３催化剂的还原性能有明显差异，反映出催化剂表面存在着不同种类的铜物种，Ａｇ的添加使催化剂的ＴＰＲ峰位发生明显位移，提高了催化剂对有机物的催人活性，同时发现，热处理温度牟催伦剂中铜物种的存在形式、催化还原特性及催化     

还原气化—无色散原子荧光光谱法连测土壤样中痕量砷、锑、汞

应用氢化法—无色散原子荧光技术分析痕量As、Sb、Bi、Se、Te、Sn已有报导。     

Redox Polymerization of Methyl Methacrylate in the Fluorous Triphasic System

Fluorous-phase chemistry is currently a topic of considerable interest1-6. Since fluoroustriphasic reactions were first described by the Curran and co-workers7, this triphasicsystem has been widely used for detagging7,8 and phase-vanishing reactions9-11. …     

硝基化合物的还原羰基化反应

硝基化合物与ＣＯ之间进行的还原羰基化反应是有机催化的新研究领域。通过硝合物的还原羰基化反应可以合成许多重要的含氮有机化合物吉异氰酸酯，氨基甲酸酯，脲，偶氮化合物和Ｎ－杂环化合物等。本文就还原羰基化反应，催化剂及催化作用机理的研究进展作一评述，其中也提及我们实验的研究工作。     

氧缺位铁酸盐的制备及结构与还原行为的研究

在３５８Ｋ下用２００ｍｌ／ｍｉｎ的空气氧化碱性悬浮液合成了ＭＦｅ_２Ｏ_（４＋δ）（δ≥０，Ｍ＝Ｆｅ、Ｃｏ、Ｎｉ、Ｍｎ），并在５７３Ｋ下用４０ｍｌ／ｍｉｎ的Ｈ_２还原ＭＦｅ_２Ｏ_（４＋δ）制备了氧缺位铁酸盐ＭＦｅ_２Ｏ_（４－δ）（δ＞０）。用ＸＲＤ、Ｍｓｓｂａｕｅｒ谱等测试方法对铁酸盐的结构进行了表征，考察了铁酸盐的组成及第二金属组分（Ｃｏ、Ｎｉ、Ｍｎ）对铁酸盐还原性能的影响。在Ｈ_２还原３ｈ内，铁酸盐氧缺位程度随还原时间增加而增大，晶格常数也相应增大；５ｈ以上，铁酸盐将被还原为ＭＯ－ＦｅＯ或α－Ｆｅ，晶格常数几乎不变。按Ｆｅ、Ｃｏ、Ｎｉ、Ｍｎ顺序，ＭＯ与ＦｅＯ的相互作用能力、ＭＯ－ＦｅＯ固溶体的稳定性及铁酸盐还原为ＭＯ－ＦｅＯ的能力均增强，ＭＯ－ＦｅＯ进一步还原为α－Ｆｅ的能力却减弱。     

碱性介质中二(碲酸根)合铜(Ⅲ)酸根氧化乙二醇一乙醚的反应动力学及机理

在碱性介质中用分光光度法研究了二过碲酸合铜(Ⅲ)配离子(DTC)氧化乙二醇一乙醚(EGE)的反应动力学及机理。反应速率表明:反应对DTC为准一级,对EGE为分数级;在保持准一级条件([EGE]》[DTC])下,表观速率常数随着OH^-浓度的增加而增大,随着TeO₄^2-浓度的增加而减小;有负的盐效应。据此提出了包括配离子和EGE形成络合物的前期平衡的反应机理,由假设反应机理推出的速率方程能很好的解释全部实验现象,进一步求得速控步的速率常数和活化