氯苄基官能化和氯苄基甲基双官能化介孔分子筛MCM-41的合成与表征

首先比较了氯苄三乙氧基硅烷和氯苄基三氯硅烷硅烷化介孔分子筛MCM-1的差异性,进而采用氯苄基三氯硅烷和甲基三氯硅烷混合试剂硅烷化介孔分子筛,一步得到氯苄基甲基双官能化介孔分子筛MCM-41,并用固体核磁予以证实.发现甲基三氯硅烷一方面可以作为一种“稀释剂”调节氯苄基的负载量,另一方面甲基的引入可增强介孔分子筛的水热稳定性.     

NMR provides checklist of generic properties for atomic-scale models of periodic mesoporous silicas

MCM-41 and SBA-15 silicas were studied by (29)Si solid-state NMR and (15)N NMR in the presence of (15)N-pyridine with the aim to formulate generic structural parameters that may be used as a checklist for atomic-scale structural models of this class of ordered mesoporous materials. High-quality MCM-41 silica constitutes quasi-ideal arrays of uniform-size pores with thin pore walls, while SBA-15 silica has thicker pore walls with framework and surface defects. The numbers of silanol (Q(3)) and silicate (Q(4)) groups were found to be in the ratio of about 1:3 for MCM-41 and about 1:4 for our SBA-15 materials. Combined with the earlier finding that the density of surface silanol groups is about three per nm(2) in MCM-41 (Shenderovich, et al. J. Phys. Chem. B 2003, 107, 11924) this allows us to discriminate between different atomic-scale models of these materials. Neither tridymite nor edingtonite meet both of these requirements. On the basis of the hexagonal pore shape model, the experimental Q(3):Q(4) ratio yields a wall thickness of about 0.95 nm for MCM-41 silica, corresponding to the width of ca. four silica tetrahedra. The arrangement of Q(3) groups at the silica surfaces was analyzed using postsynthesis surface functionalization. It was found that the number of covalent bonds to the surface formed by the functional reagents is affected by the surface morphology. It is concluded that for high-quality MCM-41 silicas the distance between neighboring surface silanol groups is greater than 0.5 nm. As a result, di- and tripodical reagents like (CH(3))(2)Si(OH)(2) and CH(3)Si(OH)(3) can form only one covalent bond to the surface. The residual hydroxyl groups of surface-bonded functional reagents either remain free or interact with other reagent molecules. Accordingly, the number of surface silanol groups at a given MCM-41 or SBA-15 silica may not decrease but increase after treatment with CH(3)Si(OH)(3) reagent. On the other hand, nearly all surface silanol groups could be functionalized when HN(Si(CH(3))(3))(2) was used.     

Immobilization of Keggin and Preyssler tungsten heteropolyacids on various functionalized silica

The Keggin and Preyssler tungsten heteropolyacids, H3PW12O40 and H15P5W30O110, have been immobilized on the inner surface of mesoporous MCM-41, fume silica and silica-gel by means of chemical bonding to aminosilane groups. The materials were characterized by FT-IR spectroscopy, low-angle XRD and BET surface area analysis. The tendencies of heteropolyacids adsorption in solution on functionalized silicas have been investigated by UV-vis. Among the functionalized silica materials, MCM-41 showed the largest amine to silica and the least heteropolyacid to silica ratios. The BET surface area revealed that in all three cases the surface area decreased after grafting amine group and anchoring of the HPAs clusters. Low-angle XRD analysis showed that by introducing HPA into functionalized MCM-41 the intensity of the main reflection decreased significantly.     

Intrinsic catalytic role of mesoporous silica in preferential oxidation of carbon monoxide in excess hydrogen

We have studied the intrinsic catalytic role of MCM-41 mesoporous silica in preferential oxidation of CO in excess H(2) (PROX). Two types of MCM-41 supports (MCM-41A and MCM-41B) were obtained from the same pristine as-synthesized materials by using different procedures for surfactant removal: one-step calcination or two-step extraction-calcination. Although two kinds of Pt catalysts prepared from the MCM-41 supports exhibit high similarity in apparent physicochemical parameters such as Pt morphology, particle-size distribution, electronic states, support architecture, and pore-size distribution, they show a dramatic difference in catalytic activity (ca. 100?% versus 10?% CO conversions at 298?K). This feature motivated us to investigate the catalytic role of MCM-41 in the PROX reaction. By means of infrared experiments with the isotope tracer technique, it was revealed that the reactive microenvironment at the interface between Pt and the MCM-41A support is the origin of the high activity. On the highly active Pt/MCM-41A catalyst, interfacial silanols play a decisive role in the ignition of CO oxidation, and gaseous O(2) and H(2) are dissociated on CO-free Pt sites created by the interfacial reaction. The dissociated oxygen and hydrogen are proposed to sustain the catalytic cycle in the form of regenerated silanols on the support, which is catalyzed by the Pt surface in the presence of H(2).     

A Novel Method for the Synthesis of Mesoporous Molecular Sieve MCM-41

Using glycerol, glycol and water as solvent, cetyltrimethylammonium bromide (CTAB) as template, tetraethyl orthosilicate (TEOS) as silica source, ethylenediamine (EDA) as base source, mesoporous molecular sieve MCM-41 has been synthesized at room temperature, characterized by X-ray power diffraction and N2 adsorption. Compared with the samples synthesized by glycol and water, the samples synthesized by glycerol have larger pore diameter and high surface areas. Thus glycerol is an efficient solvent for preparing larger pore mesoporous MCM-41.     

中孔沸石新材料MCM－41──Ⅰ．合成、酸性及稳定性

中孔沸石新材料ＭＣＭ－４１──Ⅰ．合成、酸性及稳定性赵修松，王清遐，徐龙伢，谢紊娟（中国科学院大连化学物理研究所，大连１１６０２３）李新生（中国科学院大连化学物理研究所催化基础国家重点实验室，大连１１６０２３）关键词ＭＣＭ－４１沸石，合成，酸性，稳定...     

中孔硅酸盐材料MCM-41的合成与表征研究(英文)

以十六烷基三甲基溴化铵为模板剂,硅酸钠为硅源,铝酸钠为铝源,在水热条件下成功地合成出了ＭＣＭ－４１中孔硅酸盐材料。采用ＸＲＤ、低温Ｎ２吸附脱附等测试手段对合成的ＭＣＭ－４１样品进行了表征。通过优化合成条件,合成出孔径３.２ ｎｍ、比表面９０４ｍ２／ｇ和孔壁厚约１.４６ ｎｍ的ＭＣＭ－４１分子筛。催化活性测定采用微反应活性实验来评价其活性和选择性。     

PtSn/Al2O3/MCM-41催化剂的丙烷脱氢催化性能

用微型催化反应装置评价, 并结合X射线粉末衍射(XRD)、表面积和孔结构测试、程序升温还原(TPR)、氢化学吸附和热重分析等方法研究了负载型PtSn/γ-Al2O3, PtSn/MCM-41和PtSn/Al2O3/MCM-41催化剂的丙烷脱氢反应催化性能. 发现PtSn/Al2O3/MCM-41催化剂具有较PtSn/MCM-41催化剂高的丙烷脱氢反应活性和较PtSn/γ-Al2O3催化剂高的反应稳定性. 实验结果表明, 纯硅MCM-41载体表面的锡物种因与载体相互作用较弱故易被还原, 导致铂金属分散度和催化剂的丙烷脱氢活性较低. 用Al2O3修饰MCM-41可以增强Sn物种与Al2O3/MCM-41载体之间的相互作用, 提高PtSn/Al2O3/MCM-41催化剂铂金属分散度和丙烷脱氢催化活性. 并且, 积炭后的PtSn/Al2O3/MCM-41催化剂具有较高的铂金属表面裸露度, 故具有较高的丙烷脱氢反应稳定性. PtSn/Al2O3/MCM-41催化剂优良的丙烷脱氢催化性能可能不仅与Sn-载体Al2O3/MCM-41较强的相互作用有关, 而且与Al2O3/MCM-41载体的介孔结构有关.     

MCM-41介孔分子筛共价键联钴酞菁的制备，表征及性质

采用两种方法将钴酞菁配合物共价联接到介孔分子筛MCM-41的表面：(1) 在MCM-41表面联接含伯胺的有机侧链；(2) 是在MCM-41表面联接含仲胺的有机侧链。含氯磺酸基的钴酞菁与胺反应形成磺酰胺。对得到的主客体化合物用多种物化手段和催化反应进行了表征。结果表明，钴酞菁以单体形式固定在介孔分子筛MCM-41的孔道壁上，在反应条件下固载后的钴酞菁具有高催化活性，同时表现出良好的稳定性，多次重复使用活性没有明显的改变。     

Organometallic chemistry on periodic mesoporous organosilicas: generation of surface-confined zinc and yttrium centres

Periodic mesoporous ethylenesilicas with hexagonal P6mm and cubic Fm3m/Pm3n symmetry were prepared by using divalent surfactant C(16-3-1) and binary surfactant mixtures C(18-3-1) and C18TABr as structure-directing agents, respectively, under basic conditions. A tetramethyldisilazane-based surface silylation was carried out under mild conditions affording hybrid materials SiHMe2@PMO[MCM-41], SiHMe2@PMO[KIT-5] and SiHMe2@PMO[SBA-1], corresponding to silanol group populations of ca. 1.46, 0.67 and 1.63 mmol g(-1), respectively. New molecular zinc precursor compounds Zn[N(SiHMe2)2]2 and EtZn(OSiHtBu2) were synthesized via salt metathesis and alkane elimination procedures from ZnCl2 and LiN[SiH(CH3)2]2, HOSiHtBu2 and ZnEt2, respectively. Organozinc and organoyttrium complexes were reacted with the surface silanol groups according to a heterogeneously performed silylamide route, aswell as an alkane elimination reaction, yielding Zn[N(SiHMe2)2]@PMO[MCM-41], Zn[N(SiHMe2)2]@PMO[KIT-5], Zn[N(SiHMe2)2]@PMO[SBA-1], Zn[N(SiMe3)2]@PMO[MCM-41], Zn[N(SiMe3)2]@PMO[KIT-5], Zn[N(SiMe3)2]@PMO[SBA-1], Y[N(SiHMe2)2]x(THF)y@PMO[MCM-41], Y[N(SiHMe2)2]x(THF)y@PMO[KIT-5], Y[N(SiHMe2)2]x(THF)y@PMO[SBA-1] and Zn(OSiHtBu2)@PMO[MCM-41]. The metal loading mainly depended on the surface silanol group population, size and shape of metal-coordinated ligand, and reaction time as shown for Zn contents in the range of 4.2 to 10.6 wt%. In addition, a preferred N(SiHMe2)2/OC6H2tBu2-2,6-Me-4 ligand exchangeability was found for the large yttrium surface centres. The parent and functionalized materials were characterized by powder X-ray diffraction, elemental analysis, N2 physisorption, FTIR, 13C CP and 1H MAS NMR spectroscopy.     

Amine decorated 2d hexagonal and 3d cubic mesoporous silica nanoparticles: A comprehensive dissolution kinetic study in simulated and biorelevant media

Highly ordered Bexarotene (BXR) encapsulated mesoporous silica nanoparticles in particular bare and amine functionalized MCM-41 and MCM-48 were designed employing a novel impregnation solvent evaporation strategy. The outcomes unveiled successful synthesis of mesoporous assembly having 2?D hexagonal and 3?D cubic framework for MCM-41 and MCM-48 respectively withholding large surface area, optimum pore size, pore volume along with uniform particle size distribution. Additionally, SXRD and TEM findings divulged retention of characteristic mesoporous features regardless of surface modification and drug incorporation. Eventually the release profile and release kinetics results in different dissolution media demonstrated complete drug release in simulated intestinal fluid (SIF) within 75?min and 45?min from BXR-41 and BXR-48 along with 3.33 and 5 fold increment in dissolution profile. Furthermore, lack of any interaction between gelatin of hard capsule shell and amine group in presence of enzyme were justified from the indistinguishable release pattern in enzyme free and enzyme enriched SIF media. The divergent release pattern in fed and fasted state condition having a higher release in former media strongly directs towards taking medicine after meal. Finally the release kinetics study exhibited Weibull and Higuchi model as a best fit models for bare and amine coated BXR nanoparticles respectively.     

手性修饰的介孔树脂材料负载铂催化剂上丙酮酸乙酯的不对称氢化反应

采用氯铂酸和二氯四氨合铂为前体通过浸渍法分别制备了介孔树脂材料FDU-14负载的质量分数为5%的铂催化剂Pt/FDU-14, 并利用XRD, TEM, N₂气吸附和CO化学吸附等手段对催化剂进行了表征. 考察了经过手性分子辛可尼定修饰后的Pt/FDU-14催化剂在丙酮酸乙酯不对称氢化反应中的催化性能. 以氯铂酸为前体制备的Pt/FDU-14催化剂因其具有较小的铂粒子和较高的分散度而表现出较高的活性, 乙酸溶剂中的初始活性(TOF)可以达到21902 mol/(mol?h); 而以二氯四氨合铂为前体制备的Pt/FDU-14催化剂则具有较强的手性诱导能力, 乙酸溶剂中(R)-(+)-乳酸乙酯的光学选择性可以达到81.4% e.e.. 更重要的是, 由于FDU-14具有较强的疏水性, Pt/FDU-14催化剂在水溶剂中也表现出较高的催化性能, 并且还可以重复使用10次以上.     

Influence of the pore structure of MCM-41 and SBA-15 silica fibers on atomic layer chemical vapor deposition of cobalt carbonyl

Mesoporous high surface area MCM-41 and SBA-15 type silica materials with fibrous morphology were synthesized and used as support materials for the ALCVD (atomic layer chemical vapor deposition) preparation of Co/MCM-41 and Co/SBA-15 catalysts. Co/MCM-41 and Co/SBA-15 catalysts were prepared by deposition of Co2(CO)8 from the gas phase onto the surfaces of preheated support materials in a fluidized bed reactor. For both silica materials, two different kinds of preparation methods, direct deposition and a pulse deposition method, were used. Pure silica supports as well as supported cobalt catalysts were characterized by various spectroscopic (IR) and analytical (X-ray diffraction, Brunauer-Emmett-Teller, elemental analysis) methods. MCM-41 and SBA-15 fibers showed considerable ability to adsorb Co2(CO)8 from the gas phase. For MCM-41 and SBA-15 silicas, cobalt loadings of 13.7 and 12.1 wt % were obtained using the direct deposition method. The cobalt loadings increased to 23.0 and 20.7 wt % for MCM-41 and SBA-15 silicas, respectively, when the pulse deposition method was used. The reduction behavior of silica-supported cobalt catalysts was found to depend on the catalyst preparation method and on the mesoporous structure of the support material. Almost identical reduction properties of SBA-15-supported catalysts prepared by different deposition methods are explained by the structural properties of the mesoporous support and, in particular, by the chemical structure of the inner surfaces and walls of the mesopores. Pulse O2/H2 chemisorption experiments showed catalytically promising redox properties and surface stability of the prepared MCM-41- and SBA-15-supported cobalt catalysts.     

Irreversible and reversible formation of a [2]rotaxane containing platinum(II) complex with an N-alkyl bipyridinium ligand as the axis component

An N-Alkyl bipyridinium having a polymethylene chain and a bulky aryl group at the end, [4,4'-bpy-N-(CH2)10OC6H(3)-3,5-tBu2]Cl (Cl), reacts with K[PtCl3(dmso)] to produce the Pt complex with the N-alkyl bipyridinium ligand [Cl2(dmso)Pt{4,4'-bpy-N-(CH2)10OC6H(3)-3,5-tBu2}][PtCl3(dmso)] as a 6:1 mixture of trans and cis isomers ([trans-][PtCl3(dmso)] and [cis-][PtCl3(dmso)]). Addition of alpha-cyclodextrin (alpha-CD) to a solution of Cl in dmso-d6/D2O (3:1) forms [2]pseudorotaxane [{4,4'-bpy-N-(CH2)10OC6H(3)-3,5-tBu2}.(alpha-CD)]Cl (Cl) which is equilibrated with Cl and alpha-CD in solution. The reaction of K[PtCl3(dmso)] with Cl affords the [2]rotaxane [trans-Cl2(dmso)Pt{4,4'-bpy-N-(CH2)10OC6H(3)-3,5-tBu2}.(alpha-CD)][PtCl3(dmso)] ([trans-][PtCl3(dmso)]) which contains alpha-CD and [trans-][PtCl3(dmso)] as the cyclic and axis components, respectively. Dissolution of a mixture of [trans-][PtCl3(dmso)], [cis-][PtCl3(dmso)] and alpha-CD in dmso-d6/D2O (3:1) forms a mixture of the rotaxanes containing [trans--d6][PtCl3(dmso)] and [cis--d6][PtCl3(dmso)]. The reaction involves partial dissociation of the bipyridinium from Pt of [trans-][PtCl3(dmso)] or [cis-][PtCl3(dmso)] to yield [PtCl3(dmso)] and formation of pseudorotaxane with alpha-CD, followed by recoordination of the bipyridinium to the Pt. The reversible formation of the Pt-N coordination bond is studied in a dmso solution of the N-butyl compounds [trans-Cl2(dmso)Pt{4,4'-bpy-N-nBu}][PtCl3(dmso)] ([trans-][PtCl3(dmso)]).     

Tuning selectivity in the gas phase hydrogenation of phenylacetylene over the platinum—mesoporous carbon nitride composites using organic modifiers

Russian Chemical Bulletin - The platinum nanocomposites with mesoporous carbon nitride (Pt/mpg-C3N4) were synthesized by in situ reduction of H2PtCl6·6H2O with aqueous methanol and studied as...     

Coordination chemistry of the water-soluble ligand TPPTP and formation of a [Mo(CO)5(m-TPPTP)] monolayer on an alumina surface

Phosphonate and phosphonic acid functionalized phosphine complexes of platinum(II) were prepared via direct reaction of the ligands with K2PtCl4 in water. Either cis or trans geometries were found depending on the nature of the ligand. The crystal structure of P(3-C6H4PO3H2)3.2H2O (6b) (triclinic, P1, a = 8.3501(6) A, b = 10.1907(6) A, c = 14.6529(14) A, alpha = 94.177(6) degrees, beta = 105.885(6) degrees, gamma = 108.784(5) degrees, Z = 2) shows a layered arrangement of the phosphonic acid. The phosphonodiamide complex cis-[PtCl2(P[4-C6H4PO[N(CH3]2]]3)2].3H2O (10) was synthesized in 89% yield and hydrolyzed to the phosphonic acid complex using dilute HCl. Aqueous phase and silica gel supported catalytic phosphonylation of phenyl triflate using palladium phosphine complexes was achieved. A molybdenum complex, Mo(CO)5[P3-C6H4PO3H2)3] (11), was synthesized in situ and grafted to an alumina surface. XPS, RBS, and AFM studies confirm the formation of a monolayer of 11 on the alumina surface.     

Stereospecific synthesis of polysubstituted E-olefins by reaction of acyclic nitrones with free and platinum(II) coordinated organonitriles

Free nitriles NCCH2R (1a R = CO2Me, 1b R = SO2Ph, and 1c R = COPh) with an acidic alpha-methylene react with acyclic nitrones -O+N(Me)=C(H)R' (2a R' = 4-MeC6H4 and 2b R' = 2,4,6-Me3C6H2), in refluxing CH2Cl2, to afford stereoselectively the E-olefins (NC)(R)C=C(H)R' (3a-3c and 3a'-3c'), whereas, when coordinated at the platinum(II) trans-[PtCl2(NCCH2R)2] complexes (4a R = CO2Me and 4b R = Cl), they undergo cycloaddition to give the (oxadiazoline)-PtII complexes trans-[PtCl2{N=C(CH2R)ON(Me)C(H)R'}2] (R = CO2Me, Cl and R' = 4-MeC6H4, 2,4,6-Me3C6H2) (5a-5d). Upon heating in CH2Cl2, 5a affords the corresponding alkene 3a. The reactions are greatly accelerated when carried out under focused microwave irradiation, particularly in the solid phase (SiO2), without solvent, a substantial increase of the yields being also observed. The compounds were characterized by IR and 1H, 13C, and 195Pt NMR spectroscopies, FAB+-MS, elemental analyses and, in the cases of the alkene (NC)(CO2Me)C=C(H)(4-MeC6H4) 3a and of the oxadiazoline complex trans-[PtCl2{N=C(CH2Cl)ON(Me)C(H)(4-C6H4Me)}2] 5c, also by X-ray diffraction analyses.     

Kinetic and mechanistic study of the Pt(II) versus Pt(IV) effect in the platinum-mediated nitrile-hydroxylamine coupling

The metal-mediated coupling between coordinated EtCN in the platinum(II) and platinum(IV) complexes cis- and trans-[PtCl(2)(EtCN)(2)], trans-[PtCl(4)(EtCN)(2)], a mixture of cis/trans-[PtCl(4)(EtCN)(2)] or [Ph(3)PCH(2)Ph][PtCl(n)(EtCN)] (n = 3, 5), and dialkyl- and dibenzylhydroxylamines R(2)NOH (R = Me, Et, CH(2)Ph, CH(2)C(6)H(4)Cl-p) proceeds smoothly in CH(2)Cl(2) at 20-25 degrees C and the subsequent workup allowed the isolation of new imino species [PtCl(n){NH=C(Et)ONR(2)}(2)] (n = 2, R = Me, cis-1 and trans-1; Et, cis-2 and trans-2; CH(2)Ph, cis-3 and trans-3; CH(2)C(6)H(4)Cl-p, cis-4 and trans-4; n = 4, R = Me, trans-9; Et, trans-10; CH(2)Ph, trans-11; CH(2)C(6)H(4)Cl-p, trans-12) or [Ph(3)PCH(2)Ph][PtCl(n){NH=C(Et)ONR(2)}] (n = 3, R = Me, 5; Et, 6; CH(2)Ph, 7; CH(2)C(6)H(4)Cl-p, 8; n = 5, R = Me, 13; Et, 14; CH(2)Ph, 15; CH(2)C(6)H(4)Cl-p, 16) in excellent to good (95-80%) isolated yields. The reduction of the Pt(IV) complexes 9-16 with the ylide Ph(3)P=CHCO(2)Me allows the synthesis of Pt(II) species 1-8. The compounds 1-16 were characterized by elemental analyses (C, H, N), FAB-MS, IR, (1)H, (13)C{(1)H}, and (31)P{(1)H} NMR (the latter for the anionic type complexes 5-8 and 13-16) and by X-ray crystallography for the Pt(II) (cis-1, cis-2, and trans-4) and Pt(IV) (15) species. Kinetic studies of addition of R(2)NOH (R = CH(2)C(6)H(4)Cl-p) to complexes [Ph(3)PCH(2)Ph][Pt(II)Cl(3)(EtCN)] and [Ph(3)PCH(2)Ph][Pt(IV)Cl(5)(EtCN)] by the (1)H NMR technique revealed that both reactions are first order in (p-ClC(6)H(4)CH(2))(2)NOH and Pt(II) or Pt(IV) complex, the second-order rate constant k(2) being three orders of magnitude larger for the Pt(IV) complex. The reactions are intermolecular in nature as proved by the independence of k(2) on the concentrations of added EtC triple bond N and Cl(-). These data and the calculated values of Delta H++ and Delta S++ are consistent with the mechanism involving the rate-limiting nucleophilic attack of the oxygen of (p-ClC(6)H(4)CH(2))(2)NOH at the sp-carbon of the C triple bond N bond followed by a fast proton migration.     

Simple preparations of Pd6Cl12, Pt6Cl12, and Qn[Pt2Cl8+n], n=1, 2 (Q=TBA+, PPN+) and structural characterization of [TBA][Pt2Cl9] and [PPN]2[Pt2Cl10].C7H8

The hexanuclear Pd6Cl12, i.e., the crystal phase classified as beta-PdCl2, was obtained by reacting [TBA]2[Pd2Cl6] with AlCl3 (or FeCl3) in CH2Cl2. The action of AlCl3 on PtCl42-, followed by digestion of the resulting solid in 1,2-C2H4Cl2 (DCE), CHCl3, or benzene, produced Pt6Cl12.DCE, Pt6Cl12.CHCl3, or Pt6Cl12.C6H6, respectively. Treating [TBA]2[PtCl6] with a slight excess of AlCl3 afforded [TBA][Pt2Cl9], whose anion was established crystallographically to be constituted by two "PtCl6" octahedra sharing a face. Dehydration of H2PtCl6.nH2O with SOCl2 gave an amorphous compound closely analyzing as PtCl4, reactive with [Q]Cl in SOCl2 to yield [Q][Pt2Cl9] or [Q]2[Pt2Cl10], depending on the [Q]Cl/Pt molar ratio (Q=TBA+, PPN+). A single-crystal X-ray diffraction study has shown [PPN]2[Pt2Cl10].C7H8 to contain dinuclear anions formed by two edge-sharing PtCl6 octahedra.     

电化学方法制备高分散Pt/CMK-3及其对甲醇电化学催化性能

采用直接电化学还原法在介孔碳(CMK-3)载体上直接电沉积高分散的铂纳米颗粒,制备CMK-3复合铂纳米颗粒电极(Pt/CMK-3)。 通过透射电子显微镜分析发现,铂纳米颗粒非常均匀的分布在CMK-3上,平均粒径约5 nm。 通过循环伏安测试,分析了催化剂不同负载铂含量时氯铂酸的利用率,在理论铂质量分数为20%时,这种方法制备的Pt/CMK-3所使用的氯铂酸的利用率最高,在1 mol/L CH3OH+0.5 mol/L H2SO4溶液中循环伏安测试电流密度达到382 A/g。 在相同实验条件下,Pt/CMK-3电极对甲醇电催化活性远高于Pt/XC-72(炭黑)电极和用常规电沉积方法制备的Pt/CMK-3电极。