在NiSO4表面上激光促进CO＋H2合成乙烯反应机理

利用红外光谱、程序升温脱附、程序升温表面反应和激光表面反应技术研究了固体ＮｉＳＯ_４表面上ＣＯ、Ｈ_２和Ｃ_２Ｈ_４的化学吸附性能及激光促进ＣＯ加氢合成乙烯的反应机理。实验结果表明：在硫酸镍固体表面上卧式吸附于Ｓ－Ｏ－Ｎｉ键Ｓ位和Ｎｉ位的ＣＯ是激光合成乙烯的有效吸附态；解离吸附于硫氧双键氧位上的Ｈ参与ＣＯ加氢反应；激光选择激发表面Ｓ－Ｏ键，通过能量传递和驰豫使卧式吸附态Ｃ＝Ｏ键活化并与吸附态Ｈ反应生成ＣＨ_２物种和Ｈ_２Ｏ，继而邻近的ＣＨ_２结合形成产物Ｃ_２Ｈ_４。     

CO2部分氧化乙烷制乙烯Pd—Cu／MoO3—SiO2催化剂的研究

用化学吸附－红外光谱、化学吸附－程序升温脱附（ＴＰＤ）和微型反应技术研究了Ｐｄ－Ｃｕ／ＭｏＯ３－ＳｉＯ２（ＭｏＳＯ）催化剂对ＣＯ２和乙烷的吸附活化和部分氧化反应性能．结果表明，乙烷以Ｃ—Ｈ键中的Ｈ吸附于ＭｏＳＯ载体表面ＭｏＯ键的端基氧上；Ｐｄ－Ｃｕ／ＭｏＳＯ催化剂对ＣＯ２有良好的化学吸附活化性能，ＣＯ２的吸附除有线式吸附态和剪式吸附态外，还有一种新的卧式吸附态；Ｐｄ－Ｃｕ／ＭｏＳＯ催化剂的晶格氧参与了化学反应．探讨了在Ｐｄ－Ｃｕ／ＭｏＳＯ催化剂上ＣＯ２的部分氧化乙烷反应机理     

Ni－Cu和MgO－SiO_2间的相互作用及其对催化性能的影响

本文用ＴＰＲ，ＩＲ，ＴＰＤ和ＴＰＳＲ等技术研究了以表面改性法制备的ＭｇＯ－ＳｉＯ２（ＭＳＯ）表面复合物担载的Ｎｉ－ＣＵ合金间的相互作用及其对ＣＯ加氢反应催化性能的影响．结果表明，ＮｉＯ－ＣｕＯ与ＭＳＯ间的相互作用导致部分ＭＯ与ＭＳＯ形成表面物种从而使金属组分氧化物还原温度明显升高；还原后的Ｎｉ－Ｃｕ／ＭＳＯ表面上存在着两类活性中心，即合金相中的Ｎｉ与载体相中的Ｍｇ２＋（或Ｍｇ２＋－Ｏ）；在两类活性中心的协同作用下，ＣＯ吸附除有孪生、线式和桥式吸附态物种外，还有一种新的卧式吸附态（Ｎｉ．．．Ｃ＝Ｏ→Ｍｇ２＋）．这种吸附态的活化程度较高，易在表面上发生裂解形成Ｎｉ－Ｃ和Ｍｇ２＋－Ｏ，其中Ｎｉ－Ｃ是加氢反应的碳源；Ｈ２在催化剂表面上发生解离吸附形成Ｎｉ－Ｈ和Ｍｇ２＋－ＯＨ，前者比较活泼，是加氢反应的氢原．ＣＯ加氢生成烃类的反应在Ｎｉ中心上按＂表面碳＂机理进行，其生成ＣＺＨ４的选择性高于８０％；Ｈ２Ｏ的生成反应按２（Ｍｇ２＋－ＯＨ）－→Ｍｇ２＋＋（Ｍｇ２＋－Ｏ）＋Ｈ２Ｏ方式进行．     

Ni－Cu和TiO_2－SiO_2间的相互作用及其对催化性能的影响

用表面反应改性法制备了ＴｉＯ２－ＳｉＯ２（ＴＳＯ）表面复合物载体．采用ＴＰＲ，ＩＲ，ＴＰＤＭＳ和ＴＰＳＲ－ＭＳ等技术研究了ＮＩ－Ｃｕ／ＴＳＯ间的相互作用及其对ＣＯ加氢反应的催化性能．结果表明，ＮｉＯ－ＣｕＯ与ＴＳＯ间的相互作用导致ＣｕＯ的还原温度降低和ＮｉＯ的还原温度升高，并有少量表面物种生成；还原后的Ｎｉ－Ｃｕ／ＴＳＯ催化剂表面上存在着两类活性中心，即合金相中的Ｎｉ及载体相中的Ｔｉｎ＋（或Ｔｉｎ＋－Ｏ）；ＣＯ在催化剂表面存在孪生、线式、桥式和卧式等４种吸附态；Ｈ２在催化剂表面上发生解离吸附形成Ｎｉ－Ｈ和Ｔｉｎ＋－Ｈ，前者比较活泼，是加氢反应的主要Ｈ源；卧式吸附态极易在催化剂表面裂解形成Ｎｉ－Ｃ和Ｔｉｎ＋－Ｏ，前者是加氢反应的Ｃ源，使ＣＯ加氢生成烃类的反应在Ｎｉ中心上按＂表面碳＂机理进行，其生成乙烯的选择性大于６０％．Ｈ２Ｏ的生成反应在Ｔｉｎ＋中心上按Ｔｉｎ＋－Ｏ与Ｔｉｎ＋－Ｈ或Ｎｉ－Ｈ反应的途径进行．     

激光促进H3PW12O40表面甲烷部分氧化反应

以Ｈ３ＰＷ１２Ｏ４０（ＰＷ１２）作为固体表面材料,用ＩＲ,ＴＰＤ和激光促进表面反应（ＬＳＳＲ）技术等手段考察了ＰＷ１２的表面构造、化学吸附性能和激光促进ＣＨ４部分氧化合成ＣＨ３０Ｈ的反应规律,ＰＷ１２表面上存在着Ｌｅｗｉｓ碱位（Ｗ＝Ｏ和Ｗ－Ｏ－Ｗ键中的氧位）和Ｌｅｗｉｓ酸位（－Ｗ＾６＋－）,ＣＨ４在ＰＷ１２表面的Ｌｅｗｉｓ碱位上发生化学吸附,主要吸附位是Ｗ＝Ｏ键,采用９８０ｃｍ＾－１的激光激发ＰＷ１２表面的Ｗ＝Ｏ键,在１００℃以上和常压下,ＣＨ４的部分氧化反应顺利进行,ＣＨ３ＯＨ是ＣＨ４氧化的直接产物,ＨＣＨＯ,ＣＨ３ＯＣＨ３和烃类是ＣＨ３ＯＨ进一步反应的产物,Ｈ２Ｏ分子在反应中的作用可能为：通过激光参与下Ｈ２Ｏ分子与ＰＷ１２表面发生相互作用,能产生有利于ＣＨ４吸附和ＣＨ３ＯＨ生成的表面活性位Ｗ＾６＋－Ｏ,同时     

激光促进乙醇氧化偶联反应

用ＸＲＤ、ＩＲ和脉冲ＣＯ２激光，研究了在固体Ｃｕ２（ＰＯ４）（ＯＨ）ｔ Ｐｂ３（ＰＯ４）２表面上激光促进乙醇氧化偶联的反应性能。实验结果表明：乙醇的定位化学吸附态决定着反应产物的选择性，甲基吸附态（〉Ｐ＝０…Ｈ－ＣＨ２ＣＨ２ＯＨ）反应生成１，４－丁二醇，而羟基吸附态（〉Ｐｂ…ＯＨＣＨ２ＣＨ３）则生成乙烯；固体表面构造基元的振动结构是影响激光能量利用率的主要因素，Ｃｕ２（ＰＯ４）（ＯＨ）表面Ｐ＝Ｏ键     

V2O5—SiO2表面复合物金属催化剂载体的制备与表征

采用ＶＯＣｌ２的盐酸溶液等体积浸渍ＳｉＯ２载体的表面反应方法制备了键联型Ｖ２Ｏ５－ＳｉＯ２（ＶＳＯ）表面工外光谱法（ＩＲ）研究了其表面结构状态以及对Ｃ２Ｈ６的化学吸附性能；并利用程序升温还原技术（ＴＰＲ）考察了该表面复合物载体对负载金属Ｐｄ、Ｃｕ氧化物还原过程的影响。结果表明，ＶＳＯ具有类同于载体ＳｉＯ２的孔结构和机械强度；ＶＳＯ对Ｃ２Ｈ６有一定的化学吸附能力，Ｃ２Ｈ６分子Ｃ－Ｈ键中的Ｈ吸附在ＶＳ     

应用CS_2在Ag─S键中的插入反应生成新型Ag原子簇化合物的研究（Ⅲ）──三核银Ag_3（Pr_3~iC_6H_2S）3（PPh_3）_3·（CH_3）_2CHOH的形成与晶体结构

应用ＣＳ_２在Ａｇ─Ｓ键中的单核插入物（ＰＰｈ_３）_２Ａｇ（Ｓ_２ＣＳＰｒＣ６Ｈ２）与ＣＨ_２Ｃｌ_２－Ｐｒ~ｉＯＨ混合溶剂反应，生成了一个中性的三核银簇合物。并用Ｘ射线单晶衍射法测定了其晶体结构。     

清洁及氧修饰Cu（100）表面上CO2加氢制甲醇反应的能量学

分别以清洁及氧悠Ｃｕ（１００）表面作为金属态铜和部分氧化态铜的表面模拟，用键级守恒－Ｍｏｒｅｓ势法研究了两种表面上ＣＯ２加氢制甲醇反应的能量学，计算结果表明，在两种表面上，ＣＯ２加氢制甲醇反应的优势反应途径均为“ＣＯ２，ｓ→ＨＣＯＯｓ→Ｈ２ＣＯｓ→ＣＨ３Ｏｓ→ＣＨ３ＯＨｓ”与清洁铜表面上的相应基元步骤相比，在Ｃｕ（１００）－ｐ（２×２）Ｏ表面上甲醇合成反应各基元步骤具有更低的活化能；ＨＣＯＯｓ是含     

Pd_2X_2（dpm）_2（X＝NCO~－，CH_3CO_2~－，SCN~－，

采用ＮＭＲ方法考察了室温和低温（－７８～－６０℃）下Ｐｄ２Ｘ２（ｄｐｍ）２（Ｘ＝ＮＣＯ－，ＣＨ３ＣＯ，ＳＣＮ－和ＮＯ，ｄｐｍ＝Ｐｈ２ＰＣＨ２ＰＰｈ２）与Ｈ２Ｓ在ＣＤ２Ｃｌ２或ＣＤＣｌ３中的反应。结果表明，在Ｘ＝ＮＣＯ－和ＣＨ３ＣＯ的情况下，Ｈ２Ｓ优先与这些Ｐｄ配合物的阴离子作用生成相应的共轭酸ＨＸ和Ｐｄ２（ＳＨ）２（ｄｐｍ）２，后者在Ｈ２Ｓ存在下又进一步转化为Ｐｄ２（ＳＨ）２（ｄｐｍ）２（μ－Ｓ）；当Ｘ＝ＳＣＮ－和ＮＯ时，反应则生成结构可能为［Ｐｄ２（Ｈ）（ＳＨ）（μ－ＳＨ）（ｄｐｍ）２］＋的双核Ｐｄ配合物。     

Theoretical study on the reaction mechanism of the gas-phase H2/CO2/Ni(3D) system

The ground-state potential energy surface (PES) in the gas-phase H2/CO2/Ni(3D) system is investigated at the CCSD(T)//B3LYP/6-311+G(2d,2p) levels in order to explore the possible reaction mechanism of the reverse water gas shift reaction catalyzed by Ni(3D). The calculations predict that the C-O bond cleavage of CO2 assisted by co-interacted H2 is prior to the dissociation of the H2, and the most feasible reaction path for Ni(3D) + H2 + CO2 --> Ni(3D) + H2O + CO is endothermic by 12.5 kJ mol(-1) with an energy barrier of 103.9 kJ mol(-1). The rate-determining step for the overall reaction is predicted to be the hydrogen migration with water formation. The promotion effect of H2 on the cleavage of C-O bond in CO2 is also discussed and compared with the analogous reaction of Ni(3D) + CO2 --> NiO + CO, and the difference between triplet and singlet H2/CO2/Ni systems is also discussed.     

H2-induced CO adsorption and dissociation over Co/Al2O3 catalyst

The activation of adsorbed CO is an important step in CO hydrogenation. The results from TPSR of pre-adsorbed CO with H2 and syngas suggested that the presence of H2 increased the amount of CO adsorption and accelerated CO dissocia-tion. The H2 was adsorbed first, and activated to form H* over metal sites, then reacted with carbonaceous species. The oxygen species for CO2 formation in the presence of hydrogen was mostly OH*, which reacted with adsorbed CO subsequently via CO*+OH* → CO2*+H*; however, the direct CO dissociation was not excluded in CO hydrogenation. The dissociation of C-O bond in the presence of H2 proceeded by a concerted mechanism, which assisted the Boudourd reaction of adsorbed CO onthe surface via CO*+2H* → CH*+OH*. The formation of the surface species (CH) from adsorbed CO proceeded as indicated with the participation of surface hydrogen, was favored in the initial step of the Fischer-Tropsch synthesis.     

Density functional theory of water-gas shift reaction on molybdenum carbide

The density functional theory (DFT) of the water-gas shift (WGS) reaction over molybdenum carbide was studied with the aim of understanding the dissociation of H(2)O, the OH group, and CO to determine on what sections of molybdenum carbide CO(2) and H(2) formed and whether they played a role in the reaction. The energy diagram of each elementary step, the reaction of the hydrogen and oxygen atoms with CO, and the transition state for this elementary step were also studied. The IR spectra of the CO adsorption was experimentally analyzed for the identification of several candidates of the CO adsorption modes. The adsorptions of the threefold Mo site (a) with and (b) without the underlying C atom of the second layer have the second and highest adsorption energies of -281.59 and -321.00 kJ/mol, respectively. The IR data showed that the bands at 1626 cm(-1) from the IR experiments are (a) the nearest adsorption of the threefold Mo site with the underlying C atom at the calculated/corrected band of 1621 cm(-1). The calculated/corrected threefold adsorption (b) had the highest adsorption energy but exhibited an IR band at 1147 cm(-1) which was not observed in the experimental data. The C-O bond length increased to 1.49 from 1.36 after the H(2)O adsorption (b), suggesting the dissociation of C-O after the H(2)O coadsorption. The WGS reaction on the beta-Mo(2)C(001) slab carbide was calculated and took place as follows: H(2)O was dissociated into OH and H on the Mo(2)C surface and the OH subsequently dissociated into H and O atoms. CO approached the O atom to form CO(2).     

Rh2CO2/Al2O3上H2吸附及CO和H2共吸附

CO加氢反应机理一直是许多化学工作者感兴趣的课题．Rh催化剂因其优良的性能而被用于 CO加氢机理研     

Theoretical study of the CH2 + O photodissociation of formaldehyde adsorbed on the Ag(111) surface

Configuration interaction calculations of the ground and excited states of the H2CO molecule adsorbed on the Ag(111) surface have been carried out to study the photoinduced dissociation process leading to polymerization of formaldehyde. The metal-adsorbate system has been described by the embedded cluster and multireference configuration interaction methods. The pi electron-attachment H2CO- and n-pi* internally excited H2CO* states have been considered as possible intermediates. The calculations have shown that H2CO* is only very weakly bound on Ag(111), and thus that the dissociation of adsorbed formaldehyde due to internal excitation is unlikely. By contrast, the H2CO- anion is strongly bound to Ag(111) and gains additional vibrational energy along the C-O stretch coordinate via Franck-Condon excitation from the neutral molecule. Computed energy variations of adsorbed H2CO and H2CO- at different key geometries along the pathway for C-O bond cleavage make evident, however, that complete dissociation is very difficult to attain on the potential energy surface of either of these states. Instead, reneutralization of the vibrationally excited anion by electron transfer back to the substrate is the most promising means of breaking the C-O bond, with subsequent formation of the coadsorbed O and CH2 fragments. Furthermore, it has been demonstrated that the most stable state for both dissociation fragments on Ag(111) is a closed-shell singlet, with binding energies relative to the gas-phase products of approximately 3.2 and approximately 1.3 eV for O and CH2, respectively. Further details of the reaction mechanism for the photoinduced C-O bond cleavage of H2CO on the Ag(111) surface are also given.     

Ni2P/SiO2 和Ni/SiO2 催化剂甘油氢解反应性能比较:催化剂活性及产物选择性影响因素的探讨（英文）

采用浸渍法及程序升温还原法制备了Ni2P/SiO2和Ni/SiO2催化剂,利用N2吸附-脱附、X射线衍射、X射线荧光、CO化学吸附、氢气程序升温脱附及氨气程序升温脱附等手段对催化剂进行了表征并用于甘油氢解反应.结果表明,Ni2P/SiO2和Ni/SiO2具有相近的表面Ni密度,但前者表面酸中心和表面氢物种(包括吸附氢和溢流氢)密度明显更高,且在甘油氢解反应中的活性也更高,这与其酸性中心与金属中心之间的协同作用有关.Ni2P/SiO2催化剂上主要产物为1,2-丙二醇及1-丙醇,而Ni/SiO2催化剂上主要产物为1,2-丙二醇、乙二醇和乙醇.提高反应温度和H2压力不能促进Ni2P/SiO2上乙醇和乙二醇的生成,但促进了1,2-丙二醇进一步氢解转化为1-丙醇.由此可见,Ni2P/SiO2具有较强的C-O键断裂活性及较弱的C-C键断裂活性,这可能分别与其较多酸性中心和电子及几何结构性质密切相关.     

Hydrogenation and carbon-sulfur bond hydrogenolysis of benzothiophene promoted by Re2(CO)10 and H4Re4(CO)12

In the search for metal complexes that promote the cleavage of C-S bonds in thiophenes, we observe that the reaction of Re(2)(CO)(10) and benzothiophene (BT) under a hydrogen atmosphere gives the trinuclear cluster Re(3)(mu-H)(2)(mu(3)-S-2-EtC(6)H(4))(mu-2,3-DHBT)(CO)(9) (1), which contains a hydrogenated BT ligand and a thiolate ligand resulting from the hydrogenation and cleavage of a C-S bond in BT. A detailed study of the reaction shows that Re(2)(CO)(10) initially reacts with H(2) to give H(3)Re(3)(CO)(12), which subsequently converts to H(4)Re(4)(CO)(12), which finally reacts with BT to give 1.     

Hydrogen-atom tunneling in isomerization around the C-O bond of 2-chloro-6-fluorophenol in low-temperature argon matrixes

Infrared spectra of 2-chloro-6-fluorophenol in argon matrixes at 20 K revealed the presence of a "Cl-type" isomer, which has the OH···Cl hydrogen bond, but no "F-type" isomer with OH···F bonding, in striking contrast to the existence of both isomers in the gas and liquid phases at room temperature. This finding suggests that the F-type isomer changes to the more stable Cl-type one by hydrogen-atom tunneling in the matrixes. Similar experiments on the OD···X analog species were performed to confirm the tunneling isomerization, resulting in an O-D stretching band of the F-type isomer appearing as well as that of the Cl type, like the spectra reported in the gas and liquid phases. This implies that tunneling migration of the D atom is inhibited in the argon matrix. In addition, UV-induced photoreactions of 2-chloro-6-fluorophenol were studied by a joint use of matrix-isolation IR spectroscopy assisted by density functional theory calculations. It was found that 2-fluorocyclopentadienylidenemethanone and 4-chloro-2-fluorocyclohexadienone were produced from the Cl type; the former was by the Wolff rearrangement after dissociation of the H atom in the OH group and the Cl atom, and the latter was by intramolecular migration of the H and Cl atoms. As for the deuterated F-type isomer, however, 2-chlorocyclopentadienylidenemethanone was produced by the Wolff rearrangement after dissociation of the D atom in the OD group and the F atom, besides other photoproducts of the deuterated Cl-type isomer. It is thus concluded that the tunneling isomerization around the C-O bond occurs in the OH···X species but not in the OD···X species.     

溶胶-凝胶法制备的铑基CO加氢制C2含氧化合物催化剂

用XRD,FT-IR,吸附CO的程序升温脱附(TPD),吸附CO的程序升温表面加氢反应(TPSR)等技术,并结合高压下CO加氢反应研究了用溶胶-凝胶法制备的铑基催化剂.结果表明,用溶胶-凝胶方法制备的催化剂中,Rh以极高的分散状态(主要以单原子形式)存在.与文献报道的浸渍法催化剂不同,CeO2的加入使甲醇选择性显著提高,但降低了催化剂的活性.CeO2对Rh的促进作用可能主要是CeO2与Rh产生了电子效应,即CeO2向Rh转移了电子.     

Experimental and DFT studies of the conversion of ethanol and acetic acid on PtSn-based catalysts

Reaction kinetics studies were conducted for the conversions of ethanol and acetic acid over silica-supported Pt and Pt/Sn catalysts at temperatures from 500 to 600 K. Addition of Sn to Pt catalysts inhibits the decomposition of ethanol to CO, CH4, and C2H6, such that PtSn-based catalysts are active for dehydrogenation of ethanol to acetaldehyde. Furthermore, PtSn-based catalysts are selective for the conversion of acetic acid to ethanol, acetaldehyde, and ethyl acetate, whereas Pt catalysts lead mainly to decomposition products such as CH4 and CO. These results are interpreted using density functional theory (DFT) calculations for various adsorbed species and transition states on Pt(111) and Pt3Sn(111) surfaces. The Pt3Sn alloy slab was selected for DFT studies because results from in situ (119)Sn M?ssbauer spectroscopy and CO adsorption microcalorimetry of silica-supported Pt/Sn catalysts indicate that Pt-Sn alloy is the major phase present. Accordingly, results from DFT calculations show that transition-state energies for C-O and C-C bond cleavage in ethanol-derived species increase by 25-60 kJ/mol on Pt3Sn(111) compared to Pt(111), whereas energies of transition states for dehydrogenation reactions increase by only 5-10 kJ/mol. Results from DFT calculations show that transition-state energies for CH3CO-OH bond cleavage increase by only 12 kJ/mol on Pt3Sn(111) compared to Pt(111). The suppression of C-C bond cleavage in ethanol and acetic acid upon addition of Sn to Pt is also confirmed by microcalorimetric and infrared spectroscopic measurements at 300 K of the interactions of ethanol and acetic acid with Pt and PtSn on a silica support that had been silylated to remove silanol groups.