MoO_3和α－Sb_2O_4相间氧溢流行为的研究

通过脉冲还原技术和量子化学ＤＶ－Ｘα方法研究了ＭｏＯ３和α－Ｓｂ２Ｏ４相间氧溢流行为，揭示了有关氧溢流的动力、溢流氧的本质及可能的溢流途径的信息、结果表明，氧溢流是ａ－Ｓｂ２Ｏ４自发氧化ＭｏＯ３的结果，不依赖于气相氧的存在；溢流氧是亲核性的，但依赖于亲电性晶格氧的存在；溢流氧主要被ＭｏＯ３的（０１０）面所接收．对用ＤＶ－Ｘα法进行固体氧化物电子性质研究的可行性也进行了探讨．     

MoO3和α-Sb2O4相间氧溢流行为的研究

通过脉冲还原技术和量子化学ＤＶ－Ｘα方法研究了ＭｏＯ３和αＳｂ２Ｏ４相间氧溢流行为，揭示了有关氧溢流的动力，溢流氧的本质及可能在溢流途径的信息，结果表明，氧溢流是α－Ｓｂ２Ｏ４自发氧化ＭｏＯ３的结果，不依赖于气相氧的存在，溢流氧是亲核性的，但依赖于亲电性晶格氧的存在，溢流氧主要被ＭｏＯ３的（０１０）面所接收，对用ＤＶ－Ｘα法进行固体氧化物电子性质研究的可行性也进行了探讨。     

在Pt/η-Al2O3催化剂上氢和苯吸附性能与反应行为研究

本文对氢和苯在Pt/η-Al₂O₃催化剂上的吸附性能与反应行为进行了比较详细的研究,着重探讨了氢溢流效应在催化剂表面和反应中的作用。     

甲烷在Ni/TiO_2催化剂表面的活化

考察了Ｎｉ／ＴｉＯ２催化剂甲烷部分氧化和二氧化碳重整制合成气的反应活性,实验表明,以ＴｉＯ２为载体的镍系催化剂对于甲烷部分氧化制合成气反应具有较好的活性,尤其对Ｈ２的选择性较高,对二氧化碳重整制合成气反应具有较好的低温反应活性．采用脉冲－质谱在线分析等技术,在无气相氧条件下向Ｎｉ／ＴｉＯ２催化剂脉冲ＣＨ４,发现甲烷在催化剂表面的活化（转化）及其氧化产物的选择性与金属催化剂表面氧的浓度密切相关．ＣＨ４与Ｎｉ／ＴｉＯ２催化剂作用过程中存在明显的氢溢流和氧溢流现象,可能是这种溢流效应使得Ｎ／ＴｉＯ２催化剂具有良好的反应活性和抗积碳性能．     

甲烷在Ni/TiO2催化剂表面的活化

考察了Ni/TiO2催化剂甲烷部分氧化和二氧化碳重整制合成气的反应活性,实验表明,以TiO2为载体的镍系催化剂对于甲烷部分氧化制合成气反应具有较好的活性,尤其对H2的选择性较高,对二氧化碳重整制合成气反应具有较好的低温反应活性.采用脉冲-质谱在线分析等技术,在无气相氧条件下向Ni/TiO2催化剂脉冲CH4,发现甲烷在催化剂表面的活化（转化）及其氧化产物的选择性与金属催化剂表面氧的浓度密切相关.CH4与Ni/TiO2催化剂作用过程中存在明显的氢溢流和氧溢流现象,可能是这种溢流效应使得Ni/TiO2催化剂具有良好的反应活性和抗积碳性能.     

Ni2P和MoS2催化剂在二苯并噻吩加氢脱硫反应中的氢溢流效应

对分层装填的Ni₂P//MoS₂催化剂上的二苯并噻吩加氢脱硫反应进行了研究。结果表明,分层装填的Ni₂P/Al₂O₃和MoS₂/Al₂O₃催化剂在二苯并噻吩加氢脱硫反应中存在氢溢流效应,氢溢流有助于提高MoS₂催化剂的活性位密度和加氢脱硫反应速率。由于Ni₂P比NiS_x具有更强的氢分子解离能力,Ni₂P//MoS₂催化体系的氢溢流因子略高于NiS_x//MoS₂;相对于NiS_x,Ni₂P对MoS₂催化剂是更好的助剂。     

封装型Pt/SOD分子筛的合成及表征

基于封装型贵金属分子筛的合成,充分利用其择形性和氢溢流特性构建新型加氢催化剂,选定Pt作为活性组分,方钠石作为载体,通过水热合成法直接将金属前驱体Pt(NH_3)_4Cl_2引进SOD合成母液中进行晶化,合成了不同封装量的Pt/SOD分子筛。采用苯加氢反应测试样品的催化活性,并运用XRD、SEM、TEM和H_2-TPD对样品进行表征。结果表明,合成的不同封装量的Pt/SOD样品均具有良好的催化活性,与溢流氢受体HZSM-5间均具有良好的氢溢流效应。其中,当金属前驱体Pt(NH_3)_4Cl_2的用量为(Pt(NH_3)_4Cl_2)∶(Si-Algel)比为0.030 g/g时,所合成的Pt/SOD样品最佳,催化苯加氢反应的苯转化率可达54.38%。     

金属-半导体催化剂的研究Pt/SnO_2上氢的室温溢流

本工作研究了Pt/SnO_2与气体分子H_2、CO之间的相互作用.用溢流吸附反应确证室温下氢在Pt/SnO_2表面会发生一次溢流和二次溢流.溢流氢可改变Pt/SnO_2的电导甚至能改变担体阳离子的价态.     

金属-半导体催化剂的研究Pt/SnO2上氢的室温溢流

本工作研究了Pt/SnO_2与气体分子H_2、CO之间的相互作用. 用溢流吸附反应确证室温下氢在Pt/SnO_2表面会发生一次溢流和二次溢流. 溢流氢可改变Pt/SnO_2的电导甚至能改变担体阳离子的价态.     

金属氧化物异质结气体传感器气敏增强机理

金属氧化物异质结由于费米能级效应、不同组分之间的协同作用,常被用来提高电阻型金属氧化物半导体气体传感器的气敏特性。本文简述了近年来国内外金属氧化物异质结材料的类别,主要分为混合氧化物结构、层状结构、第二相粒子修饰结构、一维纳米结构和核-壳结构;重点综述了金属氧化物异质结的气敏增强机理,包括异质结效应、协同效应、催化溢流效应、响应反型、载流子分离及微结构调控六大机理;分析了当前异质结气体传感器面临的瓶颈。最后对纳米异质结气体传感器的发展进行了展望,今后金属氧化物异质结气体传感器可以从明确异质结界面机理展开,这将为自下而上地设计出符合实际需要的气体传感器提供一定参考。     

Hydrogenation Catalysis by Hydrogen Spillover on Platinum-Functionalized Heterogeneous Boronic Acid-Polyoxometalates

The activation of molecular hydrogen is a key process in catalysis. Here, we demonstrate how polyoxometalate (POM)-based heterogeneous compounds functionalized with Platinum particles activate H₂ by synergism between a hydrogen spillover mechanism and electron-proton transfer by the POM. This interplay facilitates the selective catalytic reduction of olefins and nitroarenes with high functional group tolerance. A family of polyoxotungstates covalently functionalized with boronic acids is reported. In the solid-state, the compounds are held together by non-covalent interactions (π–π stacking and hydrogen bonding). The resulting heterogeneous nanoscale particles form stable colloidal dispersions in acetonitrile and can be surface-functionalized with platinum nanoparticles by in situ photoreduction. The resulting materials show excellent catalytic activity in hydrogenation of olefins and nitrobenzene derivatives under mild conditions (1 bar H₂ and room temperature).     

Multi-Walled Carbon Nanotubes as a Novel Promoter of Catalysts for CO/CO2 Hydrogenation to Alcohols

Multi-walled carbon-nanotubes (MWCNTs) are drawing increasing attention in recent years. This material possesses a series of unique features, such as its nanometer-sized channel, highly conductive graphitized tube-wall, sp ²-C-constructed surface, and excellent performance for adsorption and spillover of hydrogen, which make the MWCNTs full of promise to be a novel catalyst support or promoter. This article will review the recent progress in applied research of MWCNTs as a novel promoter in heterogeneous catalysis for active components, including metals and their oxides, with the emphasis on the study and development of MWCNT-promoted catalysts related to CO/CO₂ hydrogenation to alcohols and dimethyl ether based on the recent works carried out in our laboratory.     

Tuning supported catalyst reactivity with dendrimer-templated Pt-Cu nanoparticles

The effects of particle composition on heterogeneous catalysis were studied using dendrimer-encapsulated nanoparticles (DENs) as precursors to supported Pt-Cu catalysts. Bimetallic Pt-Cu DENs with varying Pt/Cu ratios were prepared in an anaerobic aqueous solution and deposited onto a high-purity commercial alumina support. The dendrimer template was then thermally removed to yield supported nanoparticle catalysts, which were studied with toluene hydrogenation and CO oxidation catalysis as well as infrared spectroscopy of adsorbed CO. Incorporating Cu into Pt nanoparticles had opposite effects on the two test reactions. Cu acted as a mild promoter for CO oxidation catalysis, and the promoting effect was independent of the amount of Cu present. Conversely, Cu acted as a strong poison for toluene hydrogenation catalysis, and the normalized rate tracked inversely with Cu content. Infrared spectroscopy of the supported nanoparticles indicated that electronic effects (electron donation from Cu to Pt) were minimal for these materials. Consequently, the catalysis results are interpreted in terms of potential structural differences as a function of Cu incorporation and reaction conditions.     

穆斯堡尔谱在多相催化研究中的应用

近年来穆斯堡尔谱在多相催化中的应用研究已取得迅速的进展。本文围绕催化工作者关心的若干问题:催化剂的制备,金属与担体的相互作用,原子簇,催化活性物种的表征等,着重对近十年来的进展,作一综合性的介绍。     

Zeolite NaY-mediated oxidation of dyes with H_2O_2: unique heterogeneous non-transition metal center cleavage of H_2O_2 under visible light irradiation

This study investigated the visible-light catalysis mediated by zeolite NaY on the oxidation of dyes with H2O2. The results demonstrated that zeolite NaY acts as a sink for the electron from the photo-excited dye in the heterogeneous catalysis. Furthermore, the electron can effectively activate H2O2 to produce ?OH radical that is a powerful oxidant for the oxidation of dye at room temperature. The effects of the framework topology, Si/Al ratio, and exchangeable cation of the zeolite on the oxidation of various dyes were also shown.     

催化剂活性位本质和构效关系的模型催化研究

明确催化剂的活性位本质和构建多相催化的结构和反应性能之间的准确关系是催化基础研究的重点,表面科学研究基于丰富的表征测试手段能够较好地在分子原子水平测定表面结构以明确催化剂活性位本质,并通过高压原位反应池测定相关催化反应性能,获得较可靠的催化剂构效关系。本文简要总结了近年来本人参与的几个模型催化研究例子,包括贵金属表面上CO和烷烃催化氧化的活性表面、纳米Au膜的制备和CO氧化的催化活性位、VO_x/Pt(111)上丙烷氧化的协同作用、Au Pd合金上醋酸乙烯酯合成Au的助催化作用、模型氧化物上纳米Pt的庚烷脱氢环化制甲苯的粒径关系等,以及相关模型催化研究技术的进展。     

Liquid-phase adsorption on metal-organic frameworks

This work is focusing on the potential application of metal-organic frameworks as porous materials in heterogeneous catalysis where the substrate is in solution. The understanding of such a liquid-phase heterogeneous catalytic process requires adsorption equilibrium data in solution. For this purpose several metal-organic frameworks were synthesized as reference materials and tested as adsorbents for the adsorption of substrate molecules such as styrene or ethylcinnamate from the liquid phase. The adsorption capacity strongly depends on the polarity of the substrate with respect to the solvent. In several instances solvent and polarity effects are heavily superimposed on the pore size effects. Adsorption isotherms, rates and hydrogenation of the substrates are reported and discussed.     

Heterogeneous catalytic asymmetric hydrogenations with modifiers of axial chirality

Studies have been made in heterogeneous hydrogenations on the possible enantioselective effects of precursors of binol-phospates, which proved to be active and effective chiral ligands in homogeneous catalysis. It was to find out, whether a modifier with axial chirality could be used in heterogeneous hydrogenations if it meets certain structural requirements. Our results show that while the conversions reach 100%, the enantiodifferentiation was negligible.     

组合多相催化研究进展*

本文对组合多相催化研究进展进行了较全面的综述,介绍了组合多相催化过程、样品库制备、库表征-高通量筛选技术及相应的微型组合反应器,并讨论了组合多相催化技术的发展趋势.     

Supported colloidal nanoparticles in heterogeneous gas phase catalysis: on the way to tailored catalysts

Using colloidally synthesized nanoparticles for the preparation of supported catalysts offers several advantages (e.g. precise control of particle size and morphology) when compared to traditional preparation techniques. Although such nanoparticles have already been very successfully used for catalytic applications in the liquid phase, applications in heterogeneous gas phase catalysis are still scarce. One aspect, usually considered as a problem, is organic stabilizers typically employed during the nanoparticle synthesis since they or their decomposition products are supposed to block catalytically active sites on the nanoparticle surface. Thus, in many studies so far, the removal of the organic ligands prior to use in gas phase catalysis has been proposed. In this perspective article, however, we will discuss a number of benefits such ligand shells may have for heterogeneous gas phase catalysis, including the protection against chemical modification, prevention of sintering and tuning of SMSI effects.