Pd／Sulfated Alumina： a Novel Catalyst for Selective Catalytic Reduction of NO with Methane

Recently ,muchattentionhasbeendirectedtotheselectivecatalyticreduction (SCR)ofNOwithmethaneasreductant[1,2 ] .Pd basedcatalystshavebeenfoundtobeactiveforthereaction[3～ 6 ] .Howev er,theperformanceofthePd basedcatalystsforthisreactiondependsstronglyonthenatureofthesup ports[3,4 ] .Sofar ,onlyacidiczeolites[3,4 ] andacidiczirconia[4～ 6 ] havebeenshowntobetheeffectivesup portsforthePd basedcatalysts .Incontrast,Pd/γ Al2 O3,whichisoneofthemostwidelyusedthree waycatalystsatpresent[7] ,exhibi…     

Reactions of [60]Fullerene with Di(azidomethyl) benzenes

Alargenumberofadditionsto[6O]fullerenehavebeeninvestigated.However,mostoftheworkhaveconcentratedontheformationofthemono-additionproductS0f[60]fullerene'-Thedevelopment0fselechveroutestomultipleadductShascurrentlybecomethefrontierinthechendstryof[60]fuIlerene'~'.FollowingtheaPplicahonoftether-directedremotefunctionalizati0ntotheregi0specificformati0nofthedi-andtriadductSof[60]fullerene,F.Diederichetal6alsodescribed'awayforthedirectdifunctionalizationof[60]fullerenebasedonacyclizationreachono…     

Chiral Schiff Base Ligands Containing Ferrocene and Pyridine Units for Ruthenium-Catalyzed Asymmetric Transfer Hydrogenation

ChiralSchiffbasecomplexesareveryefficientforawiderangeofreactions ,includingexpoxida tion[1] ,epoxideringopening[2 ] ,Diels Alderreac tion[3 ] ,aldolreaction[4 ] ,etc .However ,thereareonlyfewexamplesofP NchelateSchiffbasesbeingusedasthechiralligandsintheasymmetrictransferhydrogenationofketones .Recently ,Gaoetal[5] re portedaseriesofP ,N ,N ,PSchiffbaseligandsthathaverelativelylowenantioselectivityintheasymmet rictransferhydrogenationofketones .Here ,were portthesynthesisofaseriesofnewP …     

Low-Temperature CO Oxidation on CuO/CeO_2 Catalyst Prepared by Sol-Gel Method

Ceriaiswidelyusedasapromoterin“three waycatalysts” (TWC) .Thepromotioneffectofceriawasoriginallysupposedtobeinthestructuralaspectsandchemicalones[1] .Preciousmetalsarewidelyusedforexhaustgasemissioncontrol[2 ,3] .However,becausethehighcostofpreciousmetalsandtheirsensitivitytosulfurpoisoning ,attentionhasbeengiventonon preciousmetalcatalystssuchascopperoxide[4～ 9] .Luoetal[4 ] reportedthatCuO/CeO2 catalystshowedmarkedlyenhancedcatalyticactivityforCOoxidationduetothecombinedeffectofCuOan…     

Theoretical Studies on Electronic Structures and Spectra for C80^n （D5d,C2v） Singlet

1INTRODUCTIONC80iscalledthemissingfullereneduetoitsinstabilityinkineticsandlowerLUMO-HOMOenergygap[1],aswellasthelowerabundanceintheexperimentandthedifficultyinsynthesis[1~5].However,thestableexistenceofcomplexLa2@-C80[2]stimulatestheresearchinterestinionsofC80.Zhang[3]performedtheoreticalstudiesonthestabi-lityandNMRspectraforC80isomers.Nakao[4]cal-culatedtheLUMO-HOMOenergygapofC80byusingabinitiomolecularorbital.Hennrich[5]syn-thesizedC80(D5)fromfullerenesootextractionbydHPLC.…     

Effect of Citric Acid Solution Treatment on Textural Properties and Alkylation Activity of Zeolite Beta Catalyst

Zeolitebetaisalarge porecrystallinealuminosil icate,whichwasfirstsynthesizedbyWadlingeretal[1] in 196 7.Duetoitspeculiarframeworktopologyandsuitableacidity ,zeolitebetahasreceivedincreas ingindustrialinterestforsomeimportantreactionssuchasalkylationofbenzenewithlightolefins[2 ] andalkylationofisobutanewithbutene[3] .Manylitera turepapershavereportedmethodstomodifytheacid ityofzeolitebeta ,whichincludeion exchange ,hy drothermaltreatment ,andacidtreatment .Forexam ple ,Xieetal[4 ] investigated…     

DFT Study on the Bilayer Pentaprismane C15H10

1INTRODUCTIONInrecentyears,agreatnumberofachievementshavebeenacquiredforthemoleculeswithcage-likestructures,suchasfullerenesandpolyhedralhydro-carbon.Pentaprismane,firstlysynthesizedbyEaton,OrandBranca[1]in1981,isatypicalpolyhedralhy-drocarbon.Owingtoitssymmetricalandstrainedstructure,manystudiesincludingMM2andMM3molecularmechanicscalculations[2,,semi-empiri-3]calMNDOandAM1molecularorbitalcalcula-tions[4],abinitioHFcalculations[5～7]andDFTcal-culation[8]havebeencarriedoutonit.Recen…     

Determination of Trace Thiocyanate by a Chitosan-Modified Glassy Carbon Electrode

IntroductionMany methods for the determination ofthiocyanate,such as spectrophotometry[1— 6] ,ion-selective electrodes[7— 10 ] ,chromatography[11,12 ] ,flow- injection analysis[13 ] ,voltammetry[14 ] ,fluorimetry[15] ,amperometry[16] ,potentiometricprecipitation titration[17] have been reported. Sincethe methods have been used for the determinationof thiocyanate in waste water,biological samples,food and chemical reagents,the determination ofthiocyanate is of great significance. But theexist…     

Synthesis and Crystal Structure of 1-Phenyl-3-methyl-4-（4-bromophenyl）-6-（2-chlorophenyl）-pyrazolo[3,4-b] Pyridine under Microwave Irradiation

1INTRODUCTIONThepyrazolo[3,4-b]pyridineclassofcompoundspossessmanybiologicalandpharmacologicalactivi-ties[1],suchasactiveanti-concretionmedicaments[2]aswellasactiveanti-gramnegativeandpositivebacteriaagents[3].Thereforethesynthesesofsuchcompoundshavearousedgreatattentionofalargenumberofchemists.Themostimportantsyntheticrouteisthecondensationreaction[4～11]ofamino-pyrazoleandα,β-unsaturatedcompounds.Theorganicreactionundermicrowaveirradia-tionhastheadvantagesoffastreactionspeed,shorttime…     

超疏水多孔阵列碳纳米管薄膜

碳纳米管由于具有特异的力学[1] 、光学[2 ] 、电学[3,4 ] 和磁学性质[5] ,使其在锂离子电池[6 ] 和平板展示器[7] 等方面呈现出广泛的应用前景 .Ebbesen等[8] 对无序碳纳米管材料的浸润性进行了详细研究 ,发现其很容易被水润湿 .然而 ,阵列碳纳米管膜的浸润性研究尚未见报道 .固体表面的浸润性主要由表面化学组分和几何结构两方面控制 .通常 ,加大表面粗糙度可以增强其浸润性 [9～ 16 ] .近来 ,超疏水表面 (即与水的接触角大于 1 5 0°的表面 )的研究显示了广泛的应用背景[13～ 16 ] .这种表面通常可由增加表面粗糙度和降低表面能来制备[1…     

Ru/CNFs 催化剂催化氨分解制氢

 研究了鱼骨式碳纤维 (CNFs) 和管式碳纤维 (CNTs) 负载 Ru 催化剂的氨分解反应活性. 结果表明, Ru/CNFs 催化剂上氨分解活性高于 Ru/CNTs 催化剂. 通过改变 Ru 负载量或载体表面的含氧基团来调节 Ru 的粒径. Ru 的活性位随着 Ru 颗粒尺寸的增大而增加. CNFs 上的含氧基团对 Ru 颗粒的氨分解活性影响很大. 在相同粒径的 Ru 颗粒上, CNFs 表面的含氧基团增加了 Ru 的活性.     

Zirconia prepared from UIO-66 as a support of Ru catalyst for ammonia synthesis

The development of effective Ru catalyst for ammonia synthesis is of important practical value and scientific significance because of the wide application of ammonia as a fertilizer and its promising applications in the renewable energy. Generally, ZrO₂ was regarded as an inferior support for Ru catalyst used in ammonia synthesis. Here we prepare ZrO₂ with monoclinic phase and carbon species from ZrCl₄ following the preparation route of UiO-66 as well as ammonia treatment. Owing to the presence of a larger amount of hydrogen adsorption as well as the easier desorption of hydrogen species, the ill effect of hydrogen species on the nitrogen adsorption-desorption and ammonia synthesis can be effectively alleviated. The resulting ZrO₂-supported Ru catalyst showed 4 times higher ammonia synthesis activity than the conventional Ru/ZrO₂ obtained from zirconium nitrate.     

氧化铈负载钌催化剂中钌表面密度对氨合成活性和氢中毒的影响

氨是关系国计民生的大宗化学品,也是氢能源的重要载体.目前,世界合成氨工业每年消耗约2％的世界总能源,并排放超过1％的CO2,节能降耗需求十分迫切,其中的关键在于高性能氨合成催化剂的开发.传统观点认为,B5活性位是钌催化剂上氮解离和氨合成的活性位,当钌粒子尺寸在1.8～2.5 nm时催化剂的B5活性位数量最多,而钌尺寸较小(0.7～0.8 nm)的催化剂几乎没有氨合成活性.本文通过改变钌负载量调变了氧化铈负载钌催化剂的钌表面浓度,证实钌粒子尺寸低于2.0nm时,氧化铈负载钌催化剂也具有较高的氨合成活性.XPS等表征结果证实:钌表面密度低于0.68 Ru nm-2时,钌主要以层状形式存在于氧化铈表面,层状钌与氧化铈紧密接触,电子从氧化铈的缺陷位传递给钌物种,在这种情况下,Ru 3d5/2的结合能有所下降,氮解离能力增强,这有利于提高催化剂的氨合成活性;当钌表面密度约为0.68 Ru nm-2时,钌金属传递电子给氧化铈,此时Ru 3d5/2结合能有所增加;当钌表面密度高于1.4 Ru nm-2后,钌物种优先在层状钌表面聚集成大尺寸钌纳米粒子,此时催化剂中同时存在钌团簇和钌纳米粒子,氧化铈载体对钌粒子电子性质的影响减弱,因此大尺寸钌金属颗粒Ru 3d5/2结合能又有所下降.另一方面,氢分子会在氧化铈表面形成均裂产物(两个OH基团)或异裂产物(Ce-H和OH).同时氢分子还会在0价钌金属表面解离形成氢原子,并进一步溢流到氧化铈表面与氧原子作用形成羟基.钌活性位上的氢物种比氧化铈中的氢更容易脱附,因此氧化铈中钌的存在不仅可以增强其氢吸附量,还降低了氢物种的吸附强度.当钌表面密度低时,氧化铈与钌的相互作用较强,催化剂中的氢物种容易溢流到氧化铈中形成羟基基团,此时催化剂的氢吸附能力增强,氢中毒问题较显著.当钌表面密度较高时,氢原子在大尺寸钌颗粒上移动、反应和脱附,因此催化剂的氢中毒问题也得到显著缓解.总之,对于氧化铈负载钌催化剂,氧化铈与钌金属之间的电子相互作用以及其吸附性质都会影响催化剂的氨合成活性,因此钌表面密度低于0.31 Ru nm-2以及约为2.1 Ru nm-2时,催化剂都展现出了较高的氨合成活性.本文将为设计制备高性能钌基氨合成催化剂提供理论指导.     

Preparation and characterization of ultrathin [Ru(CO)3Cl2]2 and [BMIM][Tf2N] films on Al2O3/NiAl(110) under UHV conditions

Towards a better understanding of the interface chemistry of ionic liquid (IL) thin film catalytic systems we have applied a rigorous surface science model approach. For the first time, a model homogeneous catalyst has been prepared under ultrahigh vacuum conditions. The catalyst, di-μ-chlorobis(chlorotricarbonylruthenium) [Ru(CO)(3)Cl(2)](2), and the solvent, the IL 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [BMIM][Tf(2)N], have been deposited by physical vapor deposition onto an alumina model support [Al(2)O(3)/NiAl(110)]. First, the interaction between thin films of [Ru(CO)(3)Cl(2)](2) and the support is investigated. Then, the ruthenium complex is co-deposited with the IL and the influence of the solvent on the catalyst is discussed. D(2)O, which is a model reactant, is further added. Growth, surface interactions, and mutual interactions in the thin films are studied with IRAS in combination with density functional (DFT) calculations. At 105 K, molecular adsorption of [Ru(CO)(3)Cl(2)](2) is observed on Al(2)O(3)/NiAl(110). The IRAS spectra of the binary [Ru(CO)(3)Cl(2)](2) + [BMIM][Tf(2)N] and ternary [Ru(CO)(3)Cl(2)](2) + [BMIM][Tf(2)N] + D(2)O show every characteristic band of the individual components. Above 223 K, partial decomposition of the ruthenium complex leads to species of molecular nature attributed to Ru(CO) and Ru(CO)(2) surface species. Formation of metallic ruthenium clusters occurs above 300 K and the model catalyst decomposes further at higher temperatures. Neither the presence of the IL nor of D(2)O prevents this partial decomposition of [Ru(CO)(3)Cl(2)](2) on alumina.     

Ruthenium(II) polypyridyl complexes: potential precursors, metalloligands, and topo II inhibitors

Neutral and cationic mononuclear complexes containing both group 15 and polypyridyl ligands [Ru(kappa3-tptz)(PPh3)Cl2] [1; tptz=2,4,6-tris(2-pyridyl)-1,3,5-triazine], [Ru(kappa3-tptz)(kappa2-dppm)Cl]BF4 [2; dppm=bis(diphenylphosphino)methane], [Ru(kappa3-tptz)(PPh3)(pa)]Cl (3; pa=phenylalanine), [Ru(kappa3-tptz)(PPh3)(dtc)]Cl (4; dtc=diethyldithiocarbamate), [Ru(kappa3-tptz)(PPh3)(SCN)2] (5) and [Ru(kappa3-tptz)(PPh3)(N3)2] (6) have been synthesized. Complex 1 has been used as a metalloligand in the synthesis of homo- and heterodinuclear complexes [Cl2(PPh3)Ru(micro-tptz)Ru(eta6-C6H6)Cl]BF4 (7), [Cl2(PPh3)Ru(mu-tptz)Ru(eta6-C10H14)Cl]PF6 (8), and [Cl2(PPh3)Ru(micro-tptz)Rh(eta5-C5Me5)Cl]BF4 (9). Complexes 7-9 present examples of homo- and heterodinuclear complexes in which a typical organometallic moiety [(eta6-C6H6)RuCl]+, [(eta6-C10H14)RuCl]+, or [(eta5-C5Me5)RhCl]+ is bonded to a ruthenium(II) polypyridine moiety. The complexes have been fully characterized by elemental analyses, fast-atom-bombardment mass spectroscopy, NMR (1H and 31P), and electronic spectral studies. Molecular structures of 1-3, 8, and 9 have been determined by single-crystal X-ray diffraction analyses. Complex 1 functions as a good precursor in the synthesis of other ruthenium(II) complexes and as a metalloligand. All of the complexes under study exhibit inhibitory effects on the Topoisomerase II-DNA activity of filarial parasite Setaria cervi and beta-hematin/hemozoin formation in the presence of Plasmodium yoelii lysate.     

XPS Spectra of K-Ru/MWNTs Catalysts for Ammonia Synthesis

Alkali metal and alkali oxide-promoted ruthenium has been found to be one of the most active catalysts for ammonia synthesis under atmospheric pressure^[1]. Recently, We found^[2] that the K-Ru/MWNTs catalyst showed very high activity for ammonia synthesis. It is suggested that the high activity is due to the special electronic and structural properties of the carbon nanotubes. Alkali and alkali oxide doped MWNTs have been reported to be more favorable for electronic transfer and hydrogen storage^[3]. In the ammonia synthesis,these properties may play important roles. In this study, K-Ru/MWNTs and Ru/MWNTs were prepared and characterized by XPS. We found that alkali oxide can improve the Ru dispersion similar to the classic catalysts for ammonia synthesis.     

Probing the Electronic Effect of Carbon Nanotubes in Catalysis: NH3 Synthesis with Ru Nanoparticles

Carbon nanotubes (CNTs) have been shown to modify some properties of nanomaterials and to modify chemical reactions confined inside their channels, which are formed by curved graphene layers. Here we studied ammonia synthesis over Ru as a probe reaction to understand the effect of the electron structure of CNTs on the confined metal particles and their catalytic activity. The catalyst with Ru nanoparticles dispersed almost exclusively on the exterior nanotube surface exhibits a higher activity than the CNT‐confined Ru, although both have a similar metal particle size. Characterization with TEM, N₂ physisorption, H₂ chemisorption, temperature‐programmed reduction, CO adsorption microcalorimetry, and first‐principles calculations suggests that the outside Ru exhibits a higher electron density than the inside Ru. As a result, the dissociative adsorption of N₂, which is an electrophilic process and the rate‐determining step of ammonia synthesis, is more facile over the outside Ru than that over the inside one.     

Study of nitrosation of hexaammineruthenium(II): Crystal structure of <Emphasis Type="Italic">trans</Emphasis>-[RuNO(NH<Subscript>3</Subscript>)<Subscript>4</Subscript>Cl]Cl<Subscript>2</Subscript>

The nitrosation of [Ru(NH₃)₆]²⁺ in hydrochloric acid and alkaline ammonia media has been studied; the patterns of interconversion of ruthenium complexes in reaction solutions have been proposed. In both cases, nitrogen(II) oxide acts as the nitrosation agent. The procedure for the synthesis of [Ru(NO)(NH₃)₅]Cl₃ · H₂O (yield 75–80%), the main nitrosation product of [Ru(NH₃)₆]²⁺, has been optimized. Thermolysis of [Ru(NO)(NH₃)₅]Cl₃ · H₂O in a helium atmosphere has been studied; the intermediates have been identified. One of these products is polyamidodichloronitrosoruthenium(II) whose subsequent decomposition gives an equimolar mixture of ruthenium metal and dioxide. The structure of trans-[RuNO(NH₃)₄Cl]Cl₂, formed in the second stage of thermolysis and as a by-product in the nitrosation of [Ru(NH₃)₆]Cl₂, has been determined by X-ray diffraction.     

The subtle effects of iron-containing metal surfaces on the reductive carbonylation of RuCl3

The use of iron-containing metal surfaces, Fe, Fe-Cr-alloy and stainless steel, for the synthesis of mixed metal Ru-Fe compounds has been studied. The studied process was reductive carbonylation of RuCl3 in the presence of a metal surface. Reactions were carried out in ethanol solutions under 10-50 bar carbon monoxide pressure at 125 degrees C using an autoclave. During the reaction the metal surface was oxidized, releasing iron into the solution and acting as a sacrificial source of iron. Under these conditions the corrosion of the metal surface was facile and produced a series of iron-containing species. In addition to the formation of most obvious iron(II) products, such as [Fe(H2O)6]2+ or [FeCl2(H2O)4] the use of the metal surface also provided a route to novel labile trinuclear [Ru2Cl2(mu-Cl)4(CO)6FeL2] (L = H2O, EtOH) complexes. The stability and reactivity of the [Ru2Cl2(mu-Cl)4(CO)6FeL2] complexes were further studied using computational DFT methods. Based on the computational results a reaction route has been suggested for the formation and decomposition of [Ru2Cl2(mu-Cl)4(CO)6FeL2].     

Adsorption of [D2]methanol on Ru(001)--O surfaces: the influence of preadsorbed oxygen on the methoxide geometry.

The influence of oxygen precoverage on the bonding geometry of methoxide on Ru(001) was studied using the isotopically labeled molecule CHD2OH by reflection-absorption infrared spectroscopy (RAIRS). This molecule is an excellent model because the vibrational spectra of CHD2O- may be unambiguously correlated with the adsorption configuration. For Ru(001)--O layers with an effective oxygen coverage (theta0) between 0.25 and 0.6 ML (ML=monolayer), the influence of the oxygen precoverage was shown to vary with the initial methanol exposure. For an extremely low dose of [D2]methanol (0.01 L; L=Langmuir, 1 L=10(-6) torr s), at 90 K, no oxygen-coverage effects were detected on the geometry of [D2]methoxide: it adsorbs in an upright orientation (pseudo-C(3v) local symmetry), just as on clean Ru(001). An increase in the methanol exposure to 0.1 L, at the same temperature, results in the formation of a disordered layer of tilted methoxide: for theta(O)=0.25 ML, C(s)/C1 and intrinsic C1 configurations are present on the surface, whereas for theta(O)> or =0.5 ML, only the former species were identified. The thermal activation of these tilted layers to 105 K results in a lower coverage of upright methoxide for any oxygen precoverage, coadsorbed with decomposition products, as confirmed by the detection of adsorbed formaldehyde and, on the denser oxygen layer (theta(O)=0.6 ML), formate. The influence of the oxygen precoverage becomes determinant when annealing a [D2]methanol multilayer to 105 K: for theta(O)=0.25 ML, the RAIR spectrum correlates with a disordered layer of tilted methoxide and formaldehyde, whereas for theta(O)=0.6 ML upright methoxide, formate, and carbon monoxide were identified. On clean Ru(001), for methanol exposures > or =0.1 L, the C(3v) methoxide configuration was never attained upon thermal activation.