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1.
Polymerizations of propylene oxide (PO) have been carried out by using a series of multi-metal metal cyanide (MMC) catalysts prepared by reacting ZnCl 2 and K 3[Co(CN) 6] 2, K 4Fe(CN) 6, K 3Fe(CN) 6 and/or K 2Ni(CN) 4 in the presence of tert-butyl alcohol and polytetramethylene ether glycol as complexing agents. The resulting MMC catalysts are characterized by elemental analysis, X-ray photoelectron spectroscopy, infrared spectroscopy and X-ray powder diffraction. The structure of MMC catalysts with broadened X-ray diffraction peaks is different from that of highly crystalline Prussian blue analogues of microporous crystalline materials due to the coordination of complexing agents. The PO polymerization behavior was tunable by changing with various metal cyanide salts after fixing a main catalyst component as ZnCl 2. Even if the basic structure of the MMC complexes is different each other, i.e. orthorhombic for Zn 2[Fe(CN) 6] and monoclinic for Zn 3[Fe(CN) 6] 2 and Zn 3[Co(CN) 6] 2, the chemical formulations become more complicated by forming MMC complexes through cyano bridges and complexing agents’ coordination and the structure more distorted from the defined crystal structures. All catalysts prepared by using K 3[Co(CN) 6] 2 showed very high activity once they were activated. Simply changing catalyst formulation by choosing different metal cyanide salts, catalytic activity, induction period, polymer molecular weight and its distribution and polymer viscosity could be tuned. 相似文献
2.
The [HRh(CO)(TPPTS) 3] precursor, where TPPTS is the water-soluble P( m-C 6H 4SO 3Na) 3 ligand, has opened a large area for the Supported-Aqueous-Phase (SAP) catalysed functionalisation of heavy substrates. We investigated several ways to increase the efficiency of heavy alkenes hydroformylation by [Rh 2(μ-S tBu) 2(CO) 2(TPPTS) 2]. Addition of a cosolvent was shown to lead to a significant leaching of rhodium in the organic phase. Promising results were obtained. First, the Delmas–Chaudhari method of adding small amounts of PPh 3 to [HRh(CO)(TPPTS) 3] to maintain the complex at the interface, was examined for [Rh 2(μ-S tBu) 2(CO) 2(TPPTS) 2]. Here [Rh 2(μ-S tBu) 2(CO) 2(PPh 3) 2] was rapidly formed and is operating classically in the organic phase. Moreover, β-cyclodextrin was used as a phase-transfer agent allowing the inclusion of the substrate and its transport to the aqueous phase where the reaction is occurring. Finally, the use of silica with various hydration ratios in SAP catalysis led us to propose that the microreactors containing water, complex and extra TPPTS operate on the surface of the support. 相似文献
3.
The thermal dilatation in (NH 3 ·CH 3) SnCl 6, (NH 3 · C 2H 5) SnCl 6 and [N(CH 3)] SnCl 6 was measured, and as the results it has turned out that (NH 3 6·C 2H 5) SnCl 6 and [N(CH 3) 4] 2 SnCl 6 undergo the first order transitions at 128 K and 158 K, respectively. The low temperature phases of (NH · C 2H 5) SnCl 6 and [N(CH 3) 4] 2 SnC1 6 are found to be monoclinic and tetragonal, respectively, No phase transition was observed in (NH 3 ·CH 3) 2 SnCl 6 down to 77 K. 相似文献
4.
以 -二(1-羧乙基)咪唑盐(HL)和Zn(NO 3) 2·6H 2O反应合成二维配位聚合物[Zn(L) 2] n (Zn-L),产物再与K 2PdCl 4在四氢呋喃溶液中反应引入氮杂环卡宾-钯(NHC-Pd)催化位点,制得催化剂NHC-Pd@Zn-L,并通过PXRD、TGA、ICP、SEM、EDS和XPS进行表征。结果表明,NHC-Pd@Zn-L具有良好的热稳定性且修饰后晶体的框架结构没有发生变化,Pd以NHC-Pd的形式结合在Zn-L中,并均匀分散在配位聚合物中。将NHC-Pd@Zn-L用于催化Suzuki-Miyaura交叉偶联反应,当以苯硼酸和溴苯为底物,催化剂用量为15 mg,乙醇为溶剂,碳酸钾为碱的条件下60℃反应6 h,产率达到>99%,而且催化剂易于回收并可循环使用3次。 相似文献
5.
以 -二(1-羧乙基)咪唑盐(HL)和Zn(NO 3) 2·6H 2O反应合成二维配位聚合物[Zn(L) 2] n (Zn-L),产物再与K 2PdCl 4在四氢呋喃溶液中反应引入氮杂环卡宾-钯(NHC-Pd)催化位点,制得催化剂NHC-Pd@Zn-L,并通过PXRD、TGA、ICP、SEM、EDS和XPS进行表征。结果表明,NHC-Pd@Zn-L具有良好的热稳定性且修饰后晶体的框架结构没有发生变化,Pd以NHC-Pd的形式结合在Zn-L中,并均匀分散在配位聚合物中。将NHC-Pd@Zn-L用于催化Suzuki-Miyaura交叉偶联反应,当以苯硼酸和溴苯为底物,催化剂用量为15 mg,乙醇为溶剂,碳酸钾为碱的条件下60℃反应6 h,产率达到>99%,而且催化剂易于回收并可循环使用3次。 相似文献
6.
In the frame of research aimed at developing new synthetic procedures of multimetallic Nb-based catalysts, peroxo complexes of niobium(V) of general formula A I3[Nb(O 2) 4] and A I3[Nb(O 2) x(H yL)]· nH 2O (A I: NH 4+, CN 3H 6+ (gu); L: oxalate, tartrate, citrate) have been prepared and characterized on the basis of elemental and thermal analysis, FTIR and 13C-NMR spectra. The crystal structure of (gu) 3[Nb(O 2) 4] and (gu) 3[Nb(O 2) 2(C 2O 4) 2]·2H 2O have been determined. The application of the obtained Nb complexes as precursors for the preparation of silica-supported Nb–Mo–O catalysts has been demonstrated. Combining Nb peroxo-carboxylato compounds with analogous Mo(VI) compounds in a silica-impregnation method carried out in aqueous medium leads to the formation of the supported Nb 2Mo 3O 14 phase. 相似文献
7.
合成了5种醚基功能化酸性离子液体[Me(OEt) 1-MOR-C 3SO 3H][MeSO 3]、[Me(OEt) 2-MOR-C 3SO 3H][MeSO 3]、[Me(OEt) 3-MOR-C 3SO 3H][MeSO 3]、[2(C 3SO 3H-MOR)-(OEt) 200][2MeSO 3]、[2(C 3SO 3H-MOR)-(OEt) 400][2MeSO 3],使用红外光谱和核磁共振氢谱对合成的离子液体结构进行表征,考察离子液体的黏度、溶解性和腐蚀性。以正丁醇和乙酸的酯化反应考察了离子液体的催化活性,并使用响应面分析法优化反应工艺。结果表明,当酸醇摩尔比为1.2:1、催化剂[2(C 3SO 3H-MOR)-(OEt) 400][2MeSO 3]用量为醇质量的5%、带水剂用量为醇质量的16%时,在90℃下反应5 h,酯收率可达97.8%,离子液体经回收干燥重复使用8次催化活性没有明显的降低。 相似文献
8.
An in situ supporting method was applied to newly synthesized [(CH 2) 5(C 5H 4) 2][(C 9H 7)ZrCl 2] 2 catalyst and other commercial catalysts, and its effects on the polymerization characteristics of these catalysts were examined through reaction experiments. The changes in the molecular weight distribution varied depending on the metallocene catalyst while the changes in the catalytic activity, average molecular weight and the melting point showed the same trend. The reason for the decrease in the molecular weight with in situ supporting was discussed in relation to the co-catalysts. The polymerization characteristics of each catalyst also varied according to the alkyl aluminum, and so it is important to select a proper co-catalyst or a combination of co-catalysts to obtain a desired polymer product from each metallocene catalyst supported by in situ method. 相似文献
9.
The porosity and hydrogen storage properties of the dehydrated Prussian blue type solids Ga[Co(CN) 6], Fe 4[Fe(CN) 6] 3, M 2[Fe(CN) 6] (M = Mn, Co, Ni, Cu), and Co 3[Co(CN) 5] 2 are reported and compared to those of M 3[Co(CN) 6] 2 (M = Mn, Fe, Co, Ni, Cu, Zn). Nitrogen sorption measurements suggest partial framework collapse for M 2[Fe(CN) 6] (M = Co, Ni) and Co 3[Co(CN) 5] 2, and complete collapse for Mn 2[Fe(CN) 6]. Hydrogen sorption isotherms measured at 77 K reveal a correlation between uptake capacity and the concentration of framework vacancies, with Langmuir–Freundlich fits predicting saturation values of 1.4 wt.% for Ga[Co(CN) 6], 1.6 wt.% for Fe 4[Fe(CN) 6] 3, 2.1 wt.% for Cu 3[Co(CN) 6] 2, and 2.3 wt.% for Cu 2[Fe(CN) 6]. Enthalpies of H 2 adsorption were calculated from isotherms measured at 77 and 87 K. Importantly, the values obtained for compounds with framework vacancies are not significantly greater than for the fully-occupied framework of Ga[Co(CN) 6] (6.3–6.9 kJ/mol). This suggests that the exposed metal coordination sites in these materials do not dominate the hydrogen binding interaction. 相似文献
10.
An environmentally friendly solid acid catalyst, Ce(SO 4) 2/TiO 2 was prepared simply by modifying TiO 2 with Ce(SO 4) 2 for acid catalysis of volatile organic chemicals, 2-propanol and cumene. The characterization of prepared catalysts was performed using FTIR, XRD and DSC. The surface area of 7-Ce(SO 4) 2/TiO 2 calcined at 300 °C was very high (206.0 m 2/g) compared to that of unmodified TiO 2 (115.2 m 2/g) due to the interaction between Ce(SO 4) 2 and TiO 2. 7-Ce(SO 4) 2/TiO 2 containing 7 wt% Ce(SO 4) 2 and calcined at 300 °C exhibited maximum catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation. The catalytic activities for both reactions were correlated with the acid amounts of catalysts measured by an ammonia chemisorption method. The role of Ce results in an increase in the thermal stability of the surface sulfate species and consequently the acid amount of Ce(SO 4) 2/TiO 2 is increased. The asymmetric stretching frequency of the SO bonds for Ce(SO 4) 2/TiO 2 catalysts was related to the acidic properties and to the catalytic activity for acid catalysis to remove volatile organic chemicals, 2-propanol and cumene. 相似文献
11.
Five cationic transition metal (ethylenediamine) complexes (M=Cr(III), Co(III), Ni(II), and Cu(II)):paramolybdate anion (Mo 7O 246−) have been synthesis and characterized via their elemental analysis, magnetic susceptibility ( μeff), thermal analysis (TG and DTA), FTIR spectra, and X-ray diffraction (XRD). The FTIR study suggests that the compounds prepared be of the ion-pair type ([M(en) n] m·Mo 7O 24). Thermal study showed that molybdenum in the Cr(III), and Co(III) compounds is reduced from oxidation state (VI) to (V) at high temperature. The stoichiometries of the resulting mixed oxides at elevated temperatures (500–750°C) are: Cr 2O 3·7MoO 2.5, Co 2O 3·7MoO 2.5, 6CoOCl·7MoO 2.5, 3NiO·7MoO 3 and 3CuO·7MoO 3. Above 750°C the molybdenum oxide in the ion-pair compounds start the sublimation process. X-ray diffraction of [Cr(en) 3]·Mo 7O 24, [Co(en) 3]·Mo 7O 24, and [Cu(en) 2(H 2O) 2] 3·Mo 7O 24 shows that these complexes are crystalline solids with a similar structure, while the [Ni(en)(H 2O) 4] 3·Mo 7O 24, and [Co(en)(H 2O) 2Cl 2] 6·Mo 7O 24 ion-pair compounds display a different structure. A novel technique based on photocatalysis to eliminate Cr(VI) ions, a toxic pollutant in the environment, was applied. The photoreduction of Cr(VI) to Cr(III) ion in aqueous suspensions using new-mixed oxides as photocatalysts (Cr2O3·MoO2.5, Co2O3·MoO2.5, NiO·MoO3, and CuO·MoO3) under air-equilibration and irradiation by a medium pressure mercury lamp (UV–VIS) was investigated. 相似文献
12.
One of the key hindrances on development of solid catalysts containing cobalt species for partial oxidation of organic molecules at mild conditions in conventional liquid phase is the severe metal leaching. The leached soluble Co species with a higher degree of freedom always out-performs those of solid supported Co species in oxidation catalysis. However, the homogeneous Co species concomitantly introduces separation problems. We have recently reported for the first time, a new oxidation catalyst system for the oxidation of organic molecules in supercritical CO 2 using the principle of micellar catalysis. [CF 3(CF 2) 8COO] 2Co· xH 2O (the fluorinated anionic moiety forms aqueous reverse micelles carrying water-soluble Co 2+ cations in scCO 2) was previously shown to be extremely active for the oxidation of toluene in the presence of sodium bromide in water–CO 2 mixture, giving 98% conversion and 99% selectivity to benzoic acid at 120 °C. In this study, we show that the effects of varying the type of surfactant counterions and the length of the surfactant chains on catalysis. It is found that the use of [CF 3(CF 2) 8COO] 2Mg· yH 2O/Co(II) acetate is as effective as the [CF 3(CF 2) 8COO] 2Co· xH 2O and the fluorinated chain length used has a subtle effect on the catalytic rate measured. It is also demonstrated that this new type of micellar catalyst in scCO 2 can be easily separated via CO 2 depressurisation and be reused without noticeable deactivation. 相似文献
13.
本文利用溶液法制备了K 2Ba[B 4O 5(OH) 4] 2·8H 2O,并将其进行热处理制备得到了KBaB 5O 9,利用XRD、FT-IR、TG-DTA-DTG对样品进行了表征。分析研究了由K 2Ba[B 4O 5(OH) 4] 2·8H 2O热处理制备KBaB 5O 9过程中的物相变化过程,其物相变化经历脱结晶水、脱羟基、重结晶、再分解、熔融再结晶5个阶段,其中结晶水的脱失分两步进行。运用Kissinger法、Flynn-Wall-Ozawa法、atava-esták法对K 2Ba[B 4O 5(OH) 4] 2·8H 2O结晶水第二步脱失过程的动力学参数进行了计算,可知K 2Ba[B 4O 5(OH) 4] 2·8H 2O结晶水第二步脱失过程的活化能 Es为151.94 kJ/mol,指前因子的对数值lg As为21.25 min -1,机理函数 G(α)=(1-2 α/3)-(1- α) 2/3(其中 α为转化率)。 相似文献
14.
在配合物的水热合成过程中往往可以发现新的化学反应和催化机理。本文通过[Zn(L) 2·(H 2O) 2·(NO 3) 2](L=4(3H)-喹唑酮)配合物在130℃催化乙腈分子中的CC键断裂,原位合成化合物2-甲基-4(3H)-喹唑酮。利用红外、元素分析和X射线单晶衍射表征分析2-甲基-4(3H)-喹唑酮和[Zn(L) 2·(H 2O) 2·(NO 3) 2]的结构,结果表明[Zn(L) 2·(H 2O) 2·(NO 3) 2]和2-甲基-4(3H)-喹唑酮属于三斜晶系, P-1空间群。三组温度控制实验表明,温度对2-甲基-4(3H)-喹唑啉酮的形成有着重要的影响,并且温度高于130℃有利于该催化反应的进行。采取电喷雾质谱表征2-甲基-4(3H)-喹唑酮的形成机理发现,[Zn(L) 2·(H 2O) 2·(NO 3) 2]催化乙腈分子中的CC键断裂,生成(CN) 2和·CH 3。·CH 3有选择性地引入到4(3H)-喹唑酮中的C原子和N原子之间。本文对原位引入CH 3有着指导作用。 相似文献
15.
Ferroelectric Barium Strontium Titanate (Ba 0.5Sr 0.5TiO 3) or BST thin films on quartz substrates have been prepared by using a modified sol gel processing technique. The starting materials are Barium 2-ethylhexanoate Ba[CH 3(CH 2) 3CH(C 2H 5)CO 2] 2, Strontium 2-ethylhexanoate Sr[CH 3(CH 2) 3CH(C 2H 5)CO 2] 2 and Titanium(IV) isopropoxide [TiOCH(CH 3) 2] 4. The precursors except [TiOCH(CH 3) 2] 4 were synthesized in the laboratory. Transparent and crack-free films were fabricated on quartz substrates by spin coating. The as-fired films were found to be amorphous, which crystallized to cubic phase after annealing at 550°C in air for 1 hr. In this paper we report the structural and optical properties of BST films prepared by the modified sol-gel process.
Communicated by Prof. E. C. Subbarao 相似文献
16.
采用桥联茂金属催化体系 rac-Et(1-Ind) 2ZrCl 2/Al( iBu) 3/[Me 2NHPh] +[B(C 6F 5) 4] -催化1-癸烯聚合,考察了茂金属浓度、Al/Zr摩尔比、B/Zr摩尔比、温度、反应时间对反应转化率、黏度和摩尔质量的影响.当反应条件为1-癸烯20mL、甲苯20mL、Zr/烯摩尔比8×10 -5、Al/Zr摩尔比80、B/Zr摩尔比1.5、温度80℃、反应时间1h时,转化率达到96.2%.采用 13C NMR和 1H NMR表征了产物的结构,优化条件下所得的聚合产物具有高黏度指数(259)和低分子量分布(2.088),可作为理想的润滑油基础油的原料. 相似文献
17.
Poorly crystallized calcium hydroxide [Ca(OH) 2] yielded from portland cement pastes incorporated in calcium-polyester complexed polymer concrete (Ca-UP PC) was slowly formed during 21 days' exposure in water at 24°C. Crystal growth continued as the hydration reactions proceeded. Ca(OH) 2 formed within the amorphous organic polymer layers after up to 90 days' exposure had little if any effect on the ultimate strength of the PC composites. Ca 2+ ions increased with exposure time, and they act as strongly nucleophilic agents to enhance the formation of complexed COO −(Ca 2+) groups. These contain an ionic bond between Ca 2+ ion and carboxylate anion (COO −) produced by the hydrolysis of esters in UP polymer. 相似文献
18.
Double metal cyanide (DMC) complexes based on Zn 3[Co(CN) 6] 2 were prepared using different zinc salts and complexing agents and They were characterized by elemental analysis, IR and XRD. The catalytic properties of DMC complexes were determined in polymerization of propylene oxide. Great differences in morphology of DMC complexes was were correlated with preparation route as well as with the kind of zinc salts employed. The catalytic activity was strongly dependent on the morphology of DMC complexes and composition of catalysts. The study revealed that the amorphous catalyst made from ZnCl 2 and t-BuOH had the highest activity (up to 26 kg polymer/g catalyst). The DMC catalyst was non-stoichiometric. Polymerization of propylene oxide (PO) catalyzed by DMC proceeded in a controlled manner. The molecular weight of each polymer was controlled by the monomer/initiator ratio, the values of molecular weight distribution (MWD) were in the range of 1.23–1.48. The polymer has an atactic structure and a head-to-tail regiosequance. 相似文献
19.
The synthesis of a novel 3D aluminophosphate is described. The thermal properties of the material were investigated, and the existence of three high-temperature variants was revealed. The crystal structures of the as-synthesized material (UiO-26-as) and the material existing around 250°C (UiO-26-250) were solved from powder X-ray diffraction data. UiO-26-as with the composition [Al 4O(PO 4) 4(H 2O)] 2−[NH 3(CH 2) 3NH 3] 2+ crystallizes in the monoclinic space group P2 1/c (no. 14) with a=19.1912(5), b=9.3470(2), c=9.6375(2) Å and β=92.709(2)°. It exhibits a 3D open framework consisting of connections by PO 4 tetrahedra with AlO 4 tetrahedra, AlO 5 trigonal bipyramids and AlO 5(H 2O) octahedra forming two types of layers stacked along [1 0 0] and connected by Al–O–P bondings. The structure possesses a 1D 10-ring channel system running along [0 0 1], in which doubly protonated 1,3-diaminopropane molecules are located. UiO-26-250 with the composition [Al 4O(PO 4) 4] 2−[NH 3(CH 2) 3NH 3] 2+ crystallizes in the monoclinic space group P2 1/c with a=19.2491(4), b=9.27497(20), c=9.70189(20) Å and β=93.7929(17)°. The transformation to UiO-26-250 involves removal of the water molecule which originally is coordinated to aluminum. The rest of the structure remains virtually unchanged. The crystal structures of the two other variants existing around 400 (UiO-26-400) and 600°C (UiO-26-600) remain unknown. 相似文献
20.
The complex [(CH 3) 4N] 3[Pt(SnCl 3) 5] was selected as a molecular precursor to prepare PtSn/γ c-Al 2O 3 reforming catalysts. The spectroscopic fingerprints of the starting complex were obtained by 195Pt and 119Sn NMR and diffuse reflectance UV–visible spectroscopy. A series of supported catalysts were synthesized by wet impregnation of alumina with a solution of the precursor in acetone. Well-dispersed species are obtained for Pt loadings below 1 wt.%; at higher loadings, a second species is formed that has spectroscopic features reminiscent of the initial complex and precipitates as a separate phase. Apparently, the Pt–Sn bonds are hydrolyzed in the low-loading species and preserved in the high-loading species. The thermal transformations of PtSn/γc-Al2O3 catalysts are also studied and compared with those of the bulk precursor. In particular, it is shown that the nature of the atmosphere of thermal treatment (neutral or oxidizing) can orient the final catalyst towards preservation of an intimate Pt–Sn interaction, or towards demixtion. 相似文献
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