微波催化制备碘化亚铜球形微纳米晶体

在微波催化下,用碘单质和硝酸铜在乙醇溶液中反应,制备碘化亚铜微纳米晶体,研究功率、反应时间以及硝酸铜-乙醇溶液的浓度对碘化亚铜的形貌与粒径的影响;提出了可能存在的反应机理;用SEM、XRD对碘化亚铜微纳米晶体的形貌和晶型进行表征和分析,并且对碘化亚铜晶体的生长过程进行了分析。     

微波离子交换法制备Cu-ZSM-11及微波辐照MeOx/Cu-ZSM-11催化分解NO

用微波辐照离子交换法制备了Cu-ZSM-11,制备的Cu-ZSM-11和金属氧化物（MeO_x）机械混合制备了微波催化剂MeO_x/Cu-ZSM-11。考察了MeO_x在微波辐照下的升温行为,筛选出吸波性能好的MeO_x（MnO₂ >CuO >Ni₂O₃）为吸波组分。分别考察了微波辐照下金属氧化物、Cu-ZSM-11和MeO_x/Cu-ZSM-11直接分解NO性能,并与常规加热条件下比较。结果表明：微波辐照显著提高了NO的转化率,微波催化剂Ni₂O₃/Cu-ZSM-11在350℃时,NO转化率达到99.27%,N₂选择性达到99.9%;相同条件下,微波辐照MeO_x/Cu-ZSM-11直接分解NO转化率高于对应金属氧化物或Cu-ZSM-11分解NO的转化率,表明微波具有催化作用。微波辐照下氧气浓度对Ni₂O₃/Cu-ZSM-11直接分解NO性能几乎无影响,微波辐照消除了氧气阻抑作用,表现出微波选择效应。水汽存在对转化率有较小影响。反应进口气体不需要预热,进出口气体温度基本不变。     

微波制备CuCl_2/SiO_2-TiO_2催化剂的结构及其催化性能

采用浸渍法将CuCl_2分散到SiO_2-TiO_2载体表面,微波炉处理一定时间得到催化剂样品,考察了样品在甲醇氧化羰基化反应中的催化活性。结果表明,样品中负载CuCl_2物质的量分数为15%时,活性最佳,甲醇转化率和碳酸二甲酯选择性分别为8.25%和85.01%。微波辐射导致CuCl_2高度分散于SiO_2-TiO_2上,并与载体表面发生键合作用,降低了催化剂中对设备具有腐蚀作用的Cl含量,同时形成结构稳定的活性铜物种。     

Catalytic ozonation of dimethyl phthalate with RuO2/Al2O3 catalysts prepared by microwave irradiation

Ruthenium catalysts supported on alumina were synthesized by microwave irradiation and used to catalyze ozonation of dimethyl phthalate in water. The catalysts enhanced greatly the TOC (total organic carbon) removal. The contribution of catalysis and adsorption to the overall TOC removal were 33% and 50%, respectively. 300 W was the optimal irradiation power for catalyst preparation. Moisture content had little effect on the catalytic activity. Compared to conventional irradiation, microwave irradiation benefited the catalytic activity because it provided a homogeneous dispersion of metal on the support. It is a promising thermal treatment method for developing the catalysts used in catalytic ozonation.     

Highly active Fischer–Tropsch synthesis Co/SiO2 catalysts prepared from microwave irradiation

Studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) as well as energy-diffusive X-ray spectroscopy (EDX), a highly active Co/SiO₂ catalyst which was prepared through microwave irradiation showed more uniform and better dispersion of the Co particles within the catalyst pellets, compared to that prepared by the conventional heating method. The Fischer–Tropsch (FT) synthesis activity of the microwave-irradiated catalyst was greater than that of the conventional heating one. Not only did the catalytic activity depend on the particle distribution, but also the irradiative time. The longer irradiative time increased the catalytic activity. It was shown that the irradiative time of 14 min was an optimum. It was found that cobalt distributed uniformly inside the whole catalyst pellet prepared by the microwave irradiation. On the contrary, cobalt concentration at the outer surface, with agglomerated form, was greater than that at the center or inner part of the catalyst pellet made by the conventional heating method. Higher dispersion state of the supported cobalt, as also proved by XRD, realized at the microwave irradiated catalyst determined its improved FT activity.     

Properties of the NI/kieselguhr catalysts prepared by precipitation method

The pore structure of the 40 wt% Ni/kieselguhr catalyst prepared by precipitation of nickel component from a 0.17 M nickel nitrate solution at 90°C changes when the precipitant, 1 M Na₂CO₃ solution, is added to the nickel nitrate solution over different periods. After precipitation for 22 hours, the catalyst experiences narrowing of the pore mouth which leads to appearance of new small pores. However, when the catalyst is prepared by precipitation for 2 hours, the small pores present in the kieselguhr support are blocked by the precipitate particles and only the large pores are remained in the catalyst. The catalyst containing relatively small pores exhibits low reaction rates and changes in the product selectivity in soybean-oil hydrogenation, due to the diffusional resistance of the reactants in the catalyst pores. The effect of the diffusional resistance is not observed with CO hydrogenation, benzene hydrogenation and n-hexane hydrogenolysis, where molecular sizes of the reactants are significantly smaller than the catalyst pores.     

微波法制备的Pt/C催化剂对甲醇和CO的电催化氧化

用微波间断升温法制备了3种Pt/C催化剂,运用循环伏安和线行扫描方法测试甲醇和吸附态CO在不同方法制备的Pt/C催化剂上的电催化氧化情况。发现在酸性溶液中,对于相同Pt载量的Pt(2)和Pt(3)催化剂,Pt(3)具有较小的Pt平均粒径及较高的电催化活性;对于具有较高Pt载量的Pt(1)催化剂,具有最小的平均粒径和最高的电催化活性。     

Ni/bentonite catalysts prepared by solution combustion method for CO2 methanation

A 20 wt% Ni/bentonite catalyst was prepared by a solution combustion synthesis (SCS), which exhibited higher activity for the CO₂ methanation than that of an impregnation method (IPM), and the catalyst prepared by SCS showed a CO₂ conversion of 85% and a CH₄ selectivity of 100% at 300℃, atmospheric pressure, and 3600 ml·(g cat)^-1·h^-1, and the catalyst exhibited stable within a 110-h reaction. The results showed higher metallic Ni dispersion, smaller Ni particle size, larger specific surface area and lower reduction temperature in the Ni/bentonite prepared by SCS than that of IPM. And the Ni/bentonite prepared by the SCS moderated the interaction between NiO and bentonite.     

微波法制备HMS包络合铁配合物催化剂催化苯酚羟基化反应

以表面含氨基的HMS为载体，利用微波法在载体孔内合成8-羟基喹啉铁（FeⅡ-Oxine）、邻苯二酚铁（FeⅡ-Cat）和邻菲洛啉铁（FeⅡ-Phen）负载型催化剂（FeⅡ-L/HMS，L=Oxine，Cat或Phen），再在载体孔口接枝聚酰胺-酯型二代树状分子(A)，制得FeⅡ-L/HMS-A包络合型催化剂。XRD、FT-IR、Fe含量分析和苯酚羟基化反应结果表明，铁配合物能够被有效包络合到HMS孔内，显示出较好的苯酚羟基化活性，具有良好的重复使用性能，是一种介孔分子筛固载金属配合物简便、有效和环境友好的方法。     

微波辐射法研制复合半导体光催化材料TiO2/ZnO

采用微波辐射法制备了复合型半导体光催化材料TiO2/ZnO,利用X射线衍射(XRD)测试技术对TiO2/ZnO复合型半导体光催化材料进行了表征。用甲基红模拟有机废水,在高压汞灯模拟日光光照的条件下,研究了复合型半导体光催化材料TiO2/ZnO光催化降解有机废水的过程,并在相同的条件下,与机械研磨法制备的复合型半导体光催化材料TiO2/ZnO的光催化性能进行了对比实验。研究结果表明,微波辐射法制备的复合型半导体光催化材料TiO2/ZnO具有很好的光催化性能,TiO2/ZnO投加量为0.5g.L-1时,其具有良好的光催化脱色性能,经1h光照,对甲基红的光降解效率可以达到100%。随着溶液初始浓度增加,甲基红的降解率增大。     

CO2 hydrogenation reactivity and structure of Rh/SiO2 catalysts prepared from acetate,chloride and nitrate precursors

Silica-supported Rh catalysts (Rh/SiO₂) were prepared from acetate, chloride and nitrate precursors by an impregnation method and were applied to CO₂ hydrogenation reaction. CO₂ conversion over the catalyst prepared from chloride precursor was lower than that over acetate or nitrate one, because of fewer active sites on catalysts, as estimated by H₂ chemisorption. The main product was CO over the catalysts prepared from acetate and nitrate, but it was CH₄ over the catalyst prepared from chloride precursor. Characterization of catalysts by TEM, FT-IR and XPS was carried out in order to elucidate the effect of metal precursor on the CO₂ hydrogenation reactivity. The results of XPS showed that the O atomic ratio to Rh on surface hydroxyl groups increased in the order: chloride<nitrate<acetate precursor. The ratio of hydroxyl groups to Rh particles on SiO₂ surface was expected to have a significant influence on the reactivity.     

不同方法制备的碳载Pt-TiO_2催化剂对甲醇的电催化氧化

采用TiO2溶胶法,在不同条件下制备了碳载Pt-TiO2催化剂。运用循环伏安法、线性扫描法和计时电流法来检测甲醇在不同方法制备的碳载Pt-TiO2催化剂上的电催化氧化情况。结果发现,在酸性溶液中方法a制备的碳载Pt-TiO2催化剂对甲醇的电氧化有良好的催化活性和稳定性。     

Photocatalytic reduction of CO2 on copper-doped Titania catalysts prepared by improved-impregnation method

Photocatalytic reduction of CO₂ by copper-doped titania catalysts has been investigated. The photocatalysts with various copper species (Cu⁰, Cu^I, Cu^II) were prepared by an improved-impregnation method, where copper nitrate is doped into TiO₂ Degussa-P25. It is likely that copper present on the catalyst surface and the grain size of copper–titania catalysts is uniform, with crystallite size approximately 23 nm. The dispersion capacity of CuO in the vacant sites of TiO₂ is about 4.16 Cu²⁺ nm⁻² (≈2.2 wt% of Cu), as indicated by XRD analysis. The activation energy (E_a) for Degussa-P25 and 3%CuO/TiO₂ is ca. +26 and +12 kJ/mol, respectively. These E_a values suggest that the desorption event is a rate limiting step, and the lower E_a of 3%CuO/TiO₂ may suggest a catalytic role of copper species that enhance the methanol production.     

静电纺丝法制备高活性多孔Ni/SiO2甲烷化催化剂

以三嵌段共聚物P123为模板剂,采用静电纺丝法制备了多孔Ni/SiO₂催化剂,考察其在CO甲烷化中的催化性能。采用N₂物理吸脱附测试、扫描电子显微镜（SEM）、X射线衍射（XRD）、H₂-程序升温还原（H₂-TPR）、透射电子显微镜（TEM）、热重分析（TGA）对催化剂的结构性质进行表征。结果表明,静电纺丝法制备的多孔Ni/SiO₂催化剂活性组分Ni在SiO₂载体纤维上高度分散,比表面积大,Ni颗粒尺寸小,金属与载体相互作用强,在CO甲烷化反应中表现出优异的催化活性和稳定性。在温度450℃,压力0.1 MPa,质量空速15000 ml/（g·h）条件下,多孔Ni/SiO₂催化剂CO转化率最高可达96.4%,CH₄选择性可达86.4%。此方法为工业上制备高催化活性且无须二次成型的甲烷化催化剂提供了新思路。     

不同制备工艺的铜基合成甲醇催化剂的性能及结构

探讨不同制备工艺条件对Cu基合成甲醇催化剂性能的影响。分别采用反加共沉淀法、反加共沉淀法+助剂、并流法和并流法+助剂制备了4种催化剂样品,考察催化剂性能的变化,并对助剂在催化剂合成过程中所起的作用进行推测,采用X射线衍射、低温N₂吸附和扫描电子显微镜等对催化剂进行表征。结果表明,Cu基甲醇合成催化剂制备过程中加入助剂可以调整催化剂的孔径分布和表面组分分布,催化剂组成确定后,催化剂制备过程采用并流法+助剂制备的样品,孔径分布更合理,ZnO组分晶粒尺寸较小,Cu和Zn组分间相互接触的几率更大,催化剂性能更好。     

Structural and oxidative properties of Mn-MCM41 catalysts synthesised by MOCVD method

Molecular organic chemical vapour deposition (MOCVD) is employed to implant various gaseous manganese precursors onto mesoporous MCM-41 silica. After heat treatment in air these samples show significantly higher catalytic activity than Mn/MCM-41 samples prepared by a conventional impregnation method for trans-stilbene epoxidation to trans-stilbene oxide using tert-butylhydroperoxide (TBHP) as an oxidant. In contrast, the same MOCVD samples gave much poorer activity than the impregnation samples in diphenylmethane oxidation reaction using air as the oxidant. Catalyst characterisation (infrared, temperature programmed reduction, EXAFS, etc.) indicates that discrete entities of Mn species (Mn-oxo and/or bridging Mn-oxygen structures, etc.) are formed on the surface of the MCM-41 by the MOCVD technique. This is attributed to initial reactions of gaseous organo-manganese complexes with surface silanol groups, followed by their oxidation in air during the heat treatment. On the other hand, in the wet impregnation samples, bulk Mn oxide phases are deposited onto the MCM-41 structure. It is thus believed that the discrete supported manganese-oxygen species of high electrophilicity are the active sites for the oxygen transfer reaction in the trans-stilbene oxidation. However, the nucleophilic lattice oxygen of the bulk Mn oxide phases prepared by the wet impregnation is responsible for the effective hydrogen abstraction in the diphenylmethane oxidation. It is also evident that the catalytic activity of the MOCVD samples depends crucially on the type of precursors used. Thus, the result clearly suggests that active and ultraselective Mn-oxygen catalytic sites for a particular oxidation reaction may be tailored through the use of different chemical precursors using the MOCVD technique.     

1,2-环己二醇脱氢镍基催化剂制备方法

以硝酸镍为镍源,分别以NH3.H2O,NH4HCO3,NH3.H2O+NH4HCO3为沉淀剂采用沉淀法制备镍/硅藻土催化剂,用于1,2-环己二醇脱氢制备邻苯二酚,考察了不同沉淀剂、焙烧温度、沉淀温度制备的催化剂对1,2-环己二醇脱氢反应性能的影响,并通过XRD,BET,CO2-TPD(热设计功耗)等方法对催化剂进行了表征。结果表明:不同的沉淀剂对镍的分散度、孔结构及表面碱量都有影响,以NH3.H2O+NH4HCO3复合沉淀剂制备的镍/硅藻土催化剂上活性组分镍晶粒度小、分散度较高,催化剂平均孔径较大,催化剂表面碱中心数目多、碱量大,表现出良好的催化活性和邻苯二酚选择性。另外,催化剂适宜沉淀温度为90℃、焙烧温度为350℃。上述适宜条件制备的催化剂在320℃下用于1,2-环己二醇脱氢制备邻苯二酚,1,2-环己二醇转化率达到99.1%,邻苯二酚选择性达到86.8%。     

Hierarchical macro-mesoporous Mo/Al2O3 catalysts prepared by dual-template method for oxidative desulfurization

Journal of Porous Materials - A series of Al2O3 materials with hierarchical macro-mesoporous structure were synthesized by a dual-template method, using surfactant Pluronic P123 and polystyene (PS)...     

A single-step method for synthesis of CuInS2 nanostructures using cyclic microwave irradiation

Pure and well-crystalline CuInS₂ nanostructures were successfully synthesized via a cyclic microwave irradiation method at low microwave power using cupric chloride dihydrate (CuCl₂·2H₂O), indium chloride tetrahydrate (InCl₃·4H₂O) and thioacetamide as starting reagents. The effects of processing cycles (2–75 cycles) and microwave heating powers (180–600 W) on purity, crystallinity, particle size and morphology of the synthesized products were investigated. The synthesized products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and UV–vis spectroscopy. Increasing processing cycles and microwave heating power improved the purity and crystallinity of the synthesized products. Using the microwave powers of 450 and 600 W with 75 cycles, pure CuInS₂ nanocrystallites were obtained. The CuInS₂ crystallites displayed nanoparticles in clusters with decreasing in the diameter sizes from 1.6 to 0.9 µm when the microwave power was increased from 180 to 600 W. The reaction mechanism of the CuInS₂ formation was also provided. A CuInS₂ solar cell, made from FTO/TiO₂/CuInS₂/CdS/Pt-FTO layers, was fabricated to explore the potential use of the CuInS₂ nanoparticles in photovoltaic devices. The photovoltaic properties of the CuInS₂ solar cell including open-circuit voltage (V_oc), short-circuit current density (J_sc) and fill factor (FF) were 281.10 mV, 0.072 mA/cm² and 0.47, respectively, with cell conversion efficiency (η) of 0.01% under 1.5 AM illumination.