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1.
The copolymerization of CO and styrene catalyzed by Pd/C toward the formation of polyketones(PK)was studied in the N-valeronitrile-N'-methylimidazolium hexafluorophosphate([C4CNmim]+PF-6) medium. The synthesized PK was characterized by Fourier transform infrared(FTIR), elemental analysis, 13C-nuclear magnetic resonance(13C-NMR), differential scanning calorimetry(DSC), thermogravimetric analysis(TGA) and gel permeation chromatography(GPC). The supported ionic liquid film on the surface of Pd/C catalyst can prevent the products from covering the hole of active carbon due to its chemical stability and weak coordination ability with metal ions, and thus efficiently improve the catalytic activity. The effects of different amounts of ionic liquid on the catalytic activity and reusability of the catalyst and the molecular weight of PK were discussed. When the usage of ionic liquid is 10wt%(0.1 g ionic liquid / 1 g active carbon carrier) and the theoretical content of Pd2+ is 5wt%(0.05 g Pd2+/ 1 g active carbon carrier), the highest catalytic activity 2 963.64 gSTCO/(gPd·h) is achieved with the molecular weight and polydispersity index of PK as Mn=9 684, Mw=13 452 and Mw /Mn=1.389. 相似文献
2.
To lower the cost of polyketone synthesis, rare earth coordinate catalyst was introduced to the copoiymerization of carbon monoxide (CO) and styrene (ST) to synthesize aliphatic polyketone STCO. The catalytic system was composed of rare earth neodymium acetate, yttrium acetate, 2,2'-bipyridine, p-toluensulfonic acid, cupric p-toluensulfonate, and 1,4-benzoquinone. The catalyst and the copolymer were characterized by infrared spectrum and X-ray photoelectron spectrosco py respectively. The effects of each component of catalytic system and the kinds of rare earth acetates on catalytic activity of copoiymerization were investigated. The results show that the proposed rare earth has distinct catalytic activity in the copoiymerization of CO and ST and the maximum activity can reach 303.3 gSTCO/(mol·h). 相似文献
3.
钯负载于苯乙烯型离子交换树脂制备出负载催化剂 ,催化一氧化碳和苯乙烯的共聚合 ,考察其催化活性及使用寿命 .利用树脂的离子交换特性研究聚合体系中废液钯催化剂的重复利用 .结果表明 ,负载钯催化剂具有一定的催化活性和重复使用性 .树脂 D-72能很好离子交换聚合体系废液中的 Pd2 、Cu2 等组分 ,其重复利用催化活性可达 473 .93 g/(g· h) 相似文献
4.
N-valeronitrile-N’-methylimidazolium hexafluorophosphate ([C 4 CNmim]+ PF 6),as a novel ionic liquid with polar nitrile functional group,was prepared.The structure of the ionic liquid was characterized by using IR and 1 H NMR.As a medium,the ionic liquid plays an important role in copolymerization of carbon monoxide (CO) with styrene (St).Some synthetic conditions were determined,including the usage of ionic liquid,palladium composite catalyst and methanol,CO pressure,reaction time and reaction temperature.The influence of these factors on catalytic activity was analyzed.The results show that the catalytic activity has reached 1 724.1 gStCO/(gPd·h) and the catalyst could be reused 5 times under the optimal condition:composite catalyst 0.015 mmol,ionic liquid 3 mL,methanol 0.75 mL,CO pressure 2MPa,reaction time 2 h and reaction temperature 70℃.This CO/St copolymerization within [C 4 CNmim]+ PF 6 system could facilitate ionic liquids with efficient and economical applications to polymeric materials. 相似文献
5.
Room temperature ionic liquids as solvents for palladium-catalyzed copolymerization of carbon monoxide and styrene were prepared by reaction of aqueous lead tetrafluoroborate with correspond-ing chloride or bromide salts. The recyclability of palladium composite catalyst in various ionic liquids was investigated.[Pd(bipy)2][BF4]2 showed a lower catalytic activity than [Pd(bipy)2][PF6]2 in similar conditions, although the catalytic activity of each composite catalyst in ionic liquids still existed after 4 successive recycles. It was shown the catalytic activity of palladium composite catalyst was higher than that of the catalyst formed in situ from palladium acetate, 2,2'-bipyridyl, and HA (A=PF6-, BF4-) in ionic liquids. The effects of volume of ionic liquids, reaction time, and the dosage of benzoquinone on the copolymerization were also studied. 相似文献
6.
The effect of CaF2-doped ZrO2 catalyst for the synthesis of dimethyl carbonate （DMC） was studied by X-ray diffraction （XRD）, CO2-temperature programmed desorption （TPD）, Raman spectra, and X-ray photoelectron spectroscopy （XPS）. Catalytic performance was evaluated in the bath and distillation reactors. Results showed that the CaF2/ZrO2 catalysts had activity and stability for DMC synthesis. 相似文献
7.
In this study,Pd-Mg(Al)-LDH/γ-Al_2O_3 and Pd-Mg(Al)Zr-LDH/γ-Al_2O_3 precursors were synthesized by impregnating Na_2PdCl_4 on Mg(Al)-LDH/γ-Al_2O_3 and Mg(Al)Zr-LDH/γ-Al_2O_3,and then the precursors were calcinated and reduced to obtain Pd-Mg(Al)-MMO/γ-Al_2O_3 and Pd-Mg(Al)Zr-MMO/γ-Al_2O_3 catalysts.Compared with Pd/γ-Al_2O_3 catalyst,the hydrogenation efficiency of Pd-Mg(Al)-MMO/γ-Al_2O_3 and Pd-Mg(Al)Zr-MMO/γ-Al_2O_3 increased by 15.7%and 24.0%,respectively.Moreover,the stability of Pd-Mg(Al)Zr-MMO/γ-Al_2O_3 catalyst was also higher than that of Pd/γ-Al_2O_3.After four runs,the hydrogenation efficiency of Pd/γ-Al_2O_3 decreased from 12.1 to 10.0 g/L,while that of Pd-Mg(Al)Zr-MMO/γ-Al_2O_3 decreased from 15.0 to 14.3 g/L.The active aquinones selectivities of all catalysts were almost 99%.The structures of the catalysts were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM),N_2 adsorption-desorption,inductively coupled plasma-atomic emission spectrometry (ICP-AES),CO chemisorption analysis,transmission electron microscopy (TEM),temperature-programmed reduction with hydrogen (H_2-TPR),and X-ray photoelectron spectroscopy(XPS).The results indicate that the improved catalytic performance is attributed to the stronger interaction between Pd and Mg(Al)Zr-MMO/γ-Al_2O_3,smaller Pd particle size and higher Pd dispersion.This work develops an effective method to synthesize highly dispersed Pd nanoparticles based on the layered double hydroxides (LDHs) precursor. 相似文献
8.
An ecofriendly heterogeneous polyoxometalate (POM)-gold catalyst Au/BW11/Al2O3 was synthesized and used for solvent-free epoxidation of cyclooctene under mild reaction conditions using molecular oxygen as an oxidant and t-butyl hydroperoxide (TBHP) as an initiator. The catalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), induced coupled plasma optical emission spectrometry (ICP-OES), and Brunauer-Emmett-Teller (BET). The catalyst showed good conversion and high selectivity without use of solvents or environmentally harmful oxidants. Moreover, the catalyst is recyclable up to three cycles with no significant loss in selectivity towards epoxide. 相似文献
9.
The metal oxide/nitrogen-doped carbon (NC) compounds zirconium oxide/NC (ZrO2/NC) and cerium oxide/NC (CeO2/NC) were synthesized via the pyrolysis of polyaniline on the metal oxide surface. The characterization of the ZrO2/NC and CeO2/NC catalysts showed more active CO2 reduction reaction activity than that of NC catalyst without metal oxide. Gas chromatography analysis revealed that CO and H2 were the primary products, and no liquid-phase products were detected via proton nuclear magnetic resonance spectroscopy or high-performance liquid chromatography. The maximum Faraday efficiency of ZrO2/NC reached 90% at − 0.73 V (vs. RHE), with the current density of CO at 5.5 mA/cm2; this Faraday efficiency value was higher than that of NC (41%), with the current density of CO at 3.1 mA/cm2. The interaction between the metal oxide and carbon allowed the efficient formation of defect sites, especially imine-type nitrogen, strengthening the adsorption of the key reaction intermediate CO2•− and thus promoting the CO2 reduction reaction.
相似文献10.
采用诱导法制备空心三元PdPtCu纳米材料,利用透射电镜(TEM)、扫描电镜(SEM)和X射线衍射(XRD)对其形貌、组成和结构进行表征,并在碱性条件下测试其对乙醇氧化的电催化性能。结果表明,以氧化铜为诱导剂制备的三元PdPtCu纳米材料主要呈空心结构,且其形貌和组成可控;Pd3Pt@Cu,PdPt@Cu和PdPt3@Cu三种材料的质量电流密度分别为8 510 A·g-1,9 270 A·g-1和5 490 A·g-1,无论是质量活性还是稳定性,均明显优于商业Pd/C和商业Pt/C催化剂。 相似文献
11.
用酸预处理的活性炭作载体制备Pd/C催化剂;用XRD、N2-物理吸脱附、TEM等方法进行催化剂的结构表征.在催化剂的性能研究中发现:催化剂的活性与载体活性炭的种类、预处理和制备方法有很大的关联性.经混合酸预处理的活性炭作载体制备的Pd/C在同时具有硝基与双键的4,4'-二硝基二苯乙烯-2,2'-二磺酸二钠的催化加氢制4,4'-二氨基二苯乙烯-2,2'-二磺酸的反应中具有很好的选择性. 相似文献
12.
13.
Li-hua Teng 《浙江大学学报(A卷英文版)》2008,9(9):1288-1295
Fluidized-bed reactor is a candidate for dimethyl ether （DME） synthesis from syngas because of its excellent heat removal capability. In order to improve the attrition resistance of catalyst, an amount of silica sol as binder was added to the catalyst composed of methanol synthesis component CuO/ZnO/Al2O3 and methanol dehydration component HZSM-5, which was prepared by coprecipitation and shaped by spray drying to get spherical particles. The effect of silica sol on the catalytic activity was investigated in a fixed-bed flow microreactor. Based on the experiment results, silica sol in the range of 0-20wt% had small effect on the catalytic activity. Generally, the CO conversion and DME yield decreased with the increase in concentration of silica sol, while the attrition resistance of catalysts increased with increasing silica sol, indicating that it was feasible to improve the attrition resistance without greatly sacrificing the activity of catalyst. In addition, the characterizations of catalysts were carried out using Brunauer-Emmett-Teller （BET）, X-ray powder diffraction （XRD） and temperature programmed reduction （TPR）. 相似文献
14.
PtNi/C nanoparticles with different atomic ratios of Pt/Ni were produced in pulse microwave assisted polyol process. Transmission electron microscopy（TEM） images show uniform morphology. X-ray diffraction（XRD） pattern plus energy dispersive X-ray（EDX） spectroscopy suggests pure composition. Cyclic voltammogram study reveals that PtNi/C nanoparticles synthesized in pulse microwave assisted polyol process have better catalytic activity for the oxidation of methanol to carbon dioxide than those synthesized in continuous process. 相似文献
15.
The synthesis of methanol and dimethyl ether (DME) from CO hydrogenation has been investigated on Cu-based catalysts. A series
of Cu/ZnO/Al2O3 catalysts were prepared using a solvent-free routine which involved a direct blend of copper/zinc/aluminum salts and citric
acid, followed by calcination at 450 °C. The calcination processes were monitored using thermogravimetry differential scanning
calorimetry (TG-DSC). Catalysts were further characterized using N2 adsorption, scanning electronic microscopy (SEM), X-ray diffraction (XRD), N2O oxidation followed by H2 titration, and temperature-programmed reduction with H2 (H2-TPR). The reduction processes were also monitored with in-situ XRD. The physicochemical properties of catalysts depended
strongly on the types of precursor salts, and catalysts prepared using Al acetate and Cu nitrate as starting materials had
a larger surface area, larger exposed metallic copper surface area, and lower reduction temperature. The CO hydrogenation
performances of these catalysts were compared and discussed in terms of their structures. Catalysts prepared with copper nitrate,
zinc and aluminum acetates exhibited the highest catalytic activity. 相似文献
16.
Ethene/norbornene copolymerization by the catalyst system [Me2Si(3-tertBuCp)(NtertBu)]TiCl2/MAO was investigated in detail at 30 °C, 60 °C, and 90 °C. A mass flow controller was used in this work to obtain kinetic
data and investigate temperature's effects on activity, norbornene incorporation, copolymerization parameter, microstructure,
glass transition temperature, and molar masses were described. High copolymerization valuesr
ξ and high alternation are determined. The number of isotactic alternating sequences is much higher than that of the syndiotactic
alternating sequences. 相似文献
17.
A variety of barium sulfate （BaSO4） carriers with or without mesopore structure were synthesized via precipitation reaction in aqueous solution of barium hydroxide and sulfuric acid with ethylene glycol as a modifying agent, and then calcined at various temperatures. The obtained BaSO4 was used as catalyst carriers for polystyrene （PS） hydrogenation, and BaSO4 supported palladium （Pd） catalysts with Pd content of 5wt% were prepared by using impregnation method. N2 physisorption, transmission electron microscopy, X-ray diffraction and kinetics studies were used to investigate the effect of carrier structure on the dispersion and geometric location of active metal and their catalytic activities in PS hydrogenation. It was found that the pore structure of carrier played an important role in the dispersion and location of Pd grains. The activation energy values for all the Pd/BaSO4 catalysts were around 49.1 kJ/mol, while the pre-exponential factor for Pd/BSC-6H was much higher than others. The Pd/BSC-6H without mesopores had Pd grains deposited on the external surface of the carrier, and exhibited better activity than the mesoporous catalysts. It is indicated that the utilization of Pd/BSC-6H can reduce the pore diffusion of PS coils and enabled more active sites to participate in the PS hydrogenation. 相似文献
18.
柳长宇 《西安文理学院学报》2014,(1):71-73
通过实验制备出了Fe3O4、Fe3O4/C、Fe3O4/C/Pd纳米粒子,并将其应用于Suzuki偶联反应.以Fe3O4为载体通过溶剂热法将C包覆在Fe3O4上,再在得到的复合材料上包覆Pd得到Fe3O4/C/Pd催化剂.通过X-射线衍射(XRD)和透射电子显微镜(TEM)对产物进行表征,并对结果进行粒径形貌分析.实验结果表明,Suzuki反应在以DMF/H2O(V/V=1)为溶剂,Na2CO3为碱时,在反应温度为80℃下,反应5 h时催化剂的催化性能最佳. 相似文献
19.
Black clay(BC) was used as a catalyst for the decolorization of Azure B dye by Fenton process. BC was modified by acid, alkali, distilled water, and calcination to check their changes in characterization and efficiency on decolorization of Azure B. Among three modified catalysts, maximum decolorization was obtained by acid-modified BC(AMBC) catalyst due to the highest removal of impurities, comparatively. The characterization of AMBC was done by Fourier-transform infrared spectroscopy and X-ray diffraction spectroscopy which show the presence of metal ion. The BET surface area, pore volume, pore size, and density of AMBC were calculated to be 79.402 m~2/g, 0.0608 m~3/g, 0.00306 nm, and 16 g/cm~3, respectively. The highest decolorization of 97.59% was achieved only in 10 min using AMBC at optimized calcination of 100 °C and 3 h of aging. AMBC was considered as the main catalyst for optimizing the different process parameters. Optimized conditions were obtained: pH 2, 0.2 mL of H_2O_2, catalyst dose 0.3 g, room temperature(30 °C), and stirring speed 400 r/min. The catalyst has showed excellent stability and reusability. It could remove more than 85% of color even after four cycles of run and less than negligible leaching of iron. AMBC has good recycling ability among other modified catalysts. To check the selectivity of catalyst, different dyes such as Congo red and mixed dye(mixture of Azure B and Congo red) decolorization were studied. In the present work, kinetic study was also carried out and a three-stage decolorization process was found. 相似文献
20.
In this study, a series of novel Pt-Ni bimetallic catalysts supported on LaFeO_3/SiO_2 with different amounts of Ni were prepared by the lattice atomic-confined reduction of LaFe_(1-x)(Ni, Pt)_xO_3/SiO_2 perovskite precursors and applied in isobutane dehydrogenation to isobutene reaction. The catalysts were characterized by X-ray diffraction, H_2-temperature-programmed reduction, Brunauer-Emmett-Teller analysis, transmission electron microscopy, energy dispersive X-ray, CO chemisorption, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The as-synthesized Pt-Ni bimetallic catalysts possessed smaller most probable particle size with tunable Pt-Ni interaction, depending on the Ni content. The catalyst with Ni content of 3.0 wt% showed excellent activity and stability(the isobutane conversion and isobutene selectivity remained at about 38% and 92%, respectively, after 310 min) for the isobutane dehydrogenation reaction. It also provided approximately six times turnover frequency of the catalyst without Ni. The excellent activity and stability of the 3.0 wt% Ni-containing catalyst can be attributed to its small metal nanoparticles with high dispersion and suitable Pt-Ni interaction. Moreover, the Pt(Ni)-LaFeO_3/SiO_2 catalyst with Ni content of 3.0 wt% had been run for more than 35 h without obvious loss of activity,indicating its long-term stability, and the decrease in the Pt-Ni interaction that accompanied the formation of the FeNi alloy phase was thought to be responsible for the slight decrease in activity. 相似文献