LiCl对Fe_2O_3/SiO_2甲烷氧化偶联反应的助催化作用

使用穆斯堡尔谱，ESR和XRD等技术表征了未添加助剂和添加LiCl的Fe2O3／SiO2催化剂．XRD结果指出，添加LiCl的Fe2O／SiO2催化剂出现铁酸盐和α-方石英的衍射峰，这种结果的出现与该催化剂有较高的C2烃选择性密切相关。穆斯堡尔谱结果表明：添加LiCl的Fe2O3／SiO2催化剂有更高的结构对称性．这种结构对分子氧的活化起着重要的作用．氯的存在大大降低了氧的离解吸附的速率，减少了原子氧的吸附位的数目，并可除去吸附的原子氧，该氧种对COx的生成有利．     

高性能纳米碳材料改性Cu/ZnO/Al2O3甲醇水蒸汽重整制氢催化剂

由铜基催化剂催化甲醇水蒸汽重整制氢是有效解决车载燃料电池等制氢需求的潜在途径．但传统铜基催化剂对该反应的低温催化活性及制氢选择性均不理想．近年来碳纳米管及活性碳纤维等因具有独特的纳米孔结构、高比表面积和优异的吸附性能作为潜在的新型催化材料而备受关注．     

PHOTOCATALYTIC HYDROGEN EVOLUTION FROM WATER SPLITTING UNDER VISIBLE LIGHT IRRADIATION ON NOVEL PHOTOCATALYST FULLENES-PVP-ZN0.999NI0.001S

Fullerenes (C60/C70) linked up to Ni-doped ZnS through the medium of an amphalic polymer polyvinyl pyrrolidone (PVP) to form a new kind of photocatalyst for hydrogen evolution from aqueous Na2S/Na2SO3 solution under visible light irradiation, the photocatalytic activities of this novel photocatalyst C60/C70-PVP-Zn0.999Ni0.001S are 3-5 fold higher compared with that of precurse catalyst Zn0.999Ni0.001S. This result could be attributed to Schottky barrier layer built between C60/C70 and Zn0.999Ni0.001S due to the electro-negativity of C60 and characteristic of being used as a multiple electron acceptor. C60 or C60/C70, its moiety, with its low energy first excited singlet state, is a good energy acceptor and in addition readily accepts multiple electrons, making it a potential electron accumulate as we know, which could protect the separation between electrons and holes against combination. This is an important reason for the marked increase of amount of H2 evolution during the photocatalytic process for the composite system C60/C70-PVP-Zn0.999Ni0.001S.     

还原对Ag/SiO2催化剂高效合成吲哚的影响

以Ag／SiO2作为苯胺和乙二醇一步合成吲哚的催化剂，首次研究了还原对催化剂活性和选择性的影响．结果表明，催化剂前体在150℃以下用氢气含量不超过50%(mol)的氢-氮混合气原位还原其活性和选择性较高．     

制备方法对MoO_3／ZrO_2结构的影响及MoO_3／ZrO_2固体超强酸的结构特征 Ⅰ．ZrO_2的形态与样品比表面的研究

ＸＲＤ，ＤＴＡ，比表面测定等结果表明，制备方法对ＭｏＯ３／ＺｒＯ２结构有决定性影响．仲钼酸铵浸渍仅经干燥的Ｚｒ（ＯＨ）４再经高温焙烧所得团体超强酸ＭｏＯ３／ＺｒＯ２（Ⅰ）与浸渍晶态ＺｒＯ２所得部分氧化催化剂ＭｏＯ３／ＺｒＯ２（Ⅱ）的载体形态有明显不同．（１）ＭｏＯ３／ＺｒＯ２（Ⅰ）的比表面数倍于ＭｏＯ３／ＺｒＯ２（Ⅱ）；（２）ＭｏＯ３含量增加时，ＭｏＯ３／ＺｒＯ２（Ⅰ）的比表面逐步增大至一极大值再缓缓下降，而ＭｏＯ３／ＺｒＯ２（Ⅱ）的比表面随ＭｏＯ３含量增加而单调下降；（３）在ＭｏＯ３／ＺｒＯ２（Ⅰ）中，ＺｒＯ２以介稳四方相存在，而在ＭｏＯ３／ＺｒＯ２（Ⅱ）中则是稳定的单斜相．在此基础上研究了事先引入的活性组分在载体织构形成过程中的作用，包括延迟ＺｒＯ２晶化，阻碍晶粒长大及与之相关的相变等，并讨论了ＭｏＯ３／ＺｒＯ２（Ⅰ）中ＭｏＯ３最佳含量的科学含义．     

CoMo／Al_2O_3和CoMo／TiO_2－Al_2O_3加氢脱硫催化剂的研

研究了ＣｏＭｏ／Ａｌ２Ｏ３和ＣｏＭｏ／ＴｉＯ２－Ａｌ２Ｏ３催化剂的加氢脱硫性能，并用ＬＲＳ，ＸＲＤ和ＴＰＳ等方法表征其表面相结构和硫化行为．结果表明，以ＴｉＯ２－Ａｌ２Ｏ３为担体的Ｍｏ和ＣｏＭｏ催化剂的活性均比相应的Ａｌ２Ｏ３为担体的高；少量Ｃｏ，Ｎｉ助剂的引入可显著提高ＭｏＯ３在担体上的分散度和改进催化剂的活性；Ｃｏ助剂还有降低Ｍｏ物种硫化温度的作用．     

Synthesis of poly(styrene-co-3-trimethoxysilyl propyl methacrylate) microspheres coated with polysiloxane layer

A procedure has been developed to coat micron-sized poly(styrene-co-3-trimethoxysilyl propyl methacrylate) microspheres with a smooth layer of polysiloxane by the hydrolysis and condensation of methyl trimethoxylsilane (MTMS). Firstly, polystyrene microspheres containing silanol groups were prepared by conventional dispersion polymerization using 3-(trimethoxysilyl) propyl methacrylate (MPS) as a functional comonomer in an ethanol/water medium. Secondly, the synthesis of the polysiloxane shell was carried out using a sol–gel process of MTMS. The thickness of the shells can be easily varied with different copolymer seeds and MTMS feed ratio. When we used copolymer particles with 2.00 μm diameter as seeds, the thickness of the polysiloxane shells can be varied from 0.10 to 0.18 μm. The core/shell structure of the composite microspheres was characterized by transmission electron microscope (TEM).     

Towards accreditation of clinical biochemistry in the public sector on the island of Mauritius

Medical laboratories of the public sector as well as of the private sector on the island of Mauritius are preparing for accreditation. The clinical laboratory of the Central Health laboratory of the Ministry of Health and Quality of Life has undergone a pre-assessment by experts of the International Atomic Energy Agency (IAEA) through the aegis of a project targeted to members of the Africa Region. Several shortcomings were identified and respective corrective actions were recommended for implementation within a given time frame. In addition to ensuring the competence of the laboratory, accreditation has various positive aspects such as an increased awareness of the staff to quality and better training opportunities. The pre-assessment exercise has provided a gap analysis, which is an important aspect in the preparation towards accreditation.     

Benzylation of Aromatic Compounds with Benzyl Chloride Catalyzed by Nafion/SiO_2 Nanocomposite Catalyst

Diphenylmethane and substituted diphenylmethane are important compounds forsynthesis chemistry as well as industrial chemistry. These compounds are easilysynthesized by the benzylation of aromatic compounds with benzyl chloride or benzylalcohol catalyzed by homogeneous acid catalysts, such as AlCl3, FeCl3, H2SO4, HF andBF3. However, these catalytic systems are highly corrosive, and usually proceed withlow selectivity. In addition, they are less satisfactory from the environmen…     

过渡金属对分子筛担载Pd催化剂上CO氧化性能影响

分别采用共浸和连续浸渍法制备了一系列添加过渡金属的Pd-M-Ox-NaZSM-5(M=Cr，Mn，Fe，Co，Ni，Cu，Zn，Mo，Zr等)负载型催化剂．以CO氧化为探针反应，考察了不同制备方法对CO氧化性能影响，结果表明共浸法制备的各催化剂其活性明显优于连续浸渍法．详细考察了反应温度、Fe含量、氢气预还原、空速以及水蒸气等对共浸Pd-Fe-Ox-NaZSM-5催化剂上CO氧化行为影响，并应用XRD和XPS等手段对催化剂体相结构和表面状态进行了表征．结果表明：加入Fe2O3可明显提高Pd/NaZSM-5催化剂活性，且催化CO氧化的转化率随反应温度及Fe含量增加而增加；空速增加以及H2预还原作用导致Pd-Fe-Ox-NaZSM-5活性有所降低；催化剂对水蒸气较为敏感．XRD测试结果表明催化剂中Pd组分处于较高分散状态，以红铁矿形式存在的Fe2O3的引入，促进了Pd物种在NaZSM-5载体上的分散．表面XPS分析证实Fe2O3与Pd物种间存在较强的相互协同作用，且催化剂表面Pd物种处于较高氧化状态．Pd的高分散及其与Fe2O3的相互协同作用是共浸催化剂具有高活性的关键因素．