APPLIED ORGANOMETALLIC CHEMISTRY
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2012
·Vol. 26
·期 9
·478-482
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IF 2.061
Wenyi Chu,Xinmin Li,Yanjun Hou,Hua Wang,Hongyu Li,Xiaobin Yuan,Zhizhong Sun
Pd/C-catalyzed Suzuki–Miyaura cross-coupling between aryl bromides and arylboronic acids in 50% methanol aqueous solution proceeded smoothly in the presence of 18-crown-6. Various aryl bromides bearing electron-withdrawing groups and electron-donating groups coupled with arylboronic acid in high yields. In addition, the catalyst could be recycled five times without loss of activity. Copyright © 2012 John Wiley & Sons, Ltd.
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CHEMICAL ENGINEERING JOURNAL
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2017
·
IF 6.216
Lu Lin,Haiou Liu,Xiongfu Zhang
MOFs-based yolk-shell composites are newly-presented but promising catalysts in the area of catalysis. In this work, a kind of unique rattle-type Pd/ZnO@hollow ZIF-8 yolk-shell catalyst is developed via a ZnO-template approach, in which there exist two processes of both ZnO-induced ZIF-8 formation and ZnO dissolution. Of prime importance is that ZnO was selected as the sacrificial template since it can not only be etched in the solution of ligands but also assist the formation of compact ZIF-8 shell by providing nucleation sites via linker activation. It is also proposed that sufficient amount of Zn(NO 3 ) 2 ·6H 2 O and 2-methylimidazole added in the growth solution of ZIF-8 should accelerate the outward growth of ZIF-8 layer as well as dissolution of ZnO. This way, the final construction of Pd/ZnO@hollow ZIF-8 yolk-shell materials is achieved. Compared to the Pd/ZnO counterparts, Pd/ZnO@hollow ZIF-8 rattle-type catalysts demonstrate a promoted behavior in terms of size-selectivity for the liquid hydrogenations of alkenes due to the outer ZIF-8 shell acting as a molecular sieve. It can also protect the catalytically active Pd NPs from poisoning and leaching, giving rise to an excellent stability. Moreover, the yolk-shell catalysts manifest a better activity beyond their core-shell counterparts since the presented interior hollow space between core and shell is likely to expose more active surfaces to reactants.
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CHEMICAL ENGINEERING JOURNAL
·
2016
·
IF 5.31
Zhiqiang Zhang,Yongpeng Xu,Wenxin Shi,Wei Wang,Ruijun Zhang,Xian Bao,Bing Zhang,Li Li,Fuyi Cui
The Pd–Cu/γAl 2 O 3 catalysts were prepared by impregnation method and introduced into the cathode chamber of a divided electrochemical denitrification cell with two graphite plates as the cathode and anode, to enhance the nitrate removal efficiency and N 2 selectivity. The Pd–Cu/γAl 2 O 3 catalysts were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), specific surface area measurements (BET) and inductively coupled plasma-atomic emission spectrometry (ICP-AES). In the rationally designed electrochemical-catalytic (ECC) system, the as-prepared catalyst could significantly enhance the nitrate degradation rate to 1.08 mg/L at current density of 10 mA/cm 2 , which was approx. 2.5 times compared with the electrochemical (EC) system without catalysts adding in. Additionally, a higher nitrogen selectivity of 80.37% was obtained under the same experiment condition. The improved performances were likely due to the presence of a catalytic reduction reaction of nitrate with the appropriate amount of hydrogen generated by electrolysis as reductant. Significantly, the current efficiency was calculated and enhanced value of 20–40% (depended on current density) was obtained in the ECC process with a catalyst content of 1.0 g/L.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2016
·
IF 3.205
Nan Mei,Bing Liu
Catalytic reduction of nitro compounds to the amines is of high importance in modern synthetic chemistry . In this study, an efficient method was developed for the transfer hydrogenation of nitro compounds over a magnetic Pd catalyst by the use of NaBH 4 as the hydrogen donor . Full nitrobenzene conversion and high selectivity (>99%) of aniline were produced after 1 h at 60 °C in ethanol. The reductions are successfully carried out in presence of a wide variety of other reducible functional groups in the molecule, except halogen and vinyl substitute nitrobenzene. Kinetic studies indicated the active energy for the transfer hydrogenation of nitrobenzene was 20.93 KJ mol −1 . The transfer hydrogenation of nitrobenzene was confirmed to proceed via azobenzene as the intermediate. More importantly, the catalyst was very stable without the loss of its catalytic activity .
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APPLIED CATALYSIS A-GENERAL
·
2017
·
IF 4.339
Lujie Liu,Hui Lou,Min Chen
Nano-Pt and Nano-Pd particles were introduced to modified multiwalled carbon nanotubes via co-impregnation method for hydrogenation of furfural in liquid phase using ethanol as a solvent. Different transition metal (Cr, Mn, Fe, Co, Ni) was used as promoters using Pt/MWNT and Pd/MWNT catalysts and various supports were also compared to further investigate the hydrogenation process of furfural. Among the catalysts investigated, Pt–Fe/MWNT (Pt: 0.5 wt%) showed highest conversion and selectivity to furfuryl alcohol (yield of 87.4%), while Pd–Ni/MWNT (Pd: 0.5 wt%) catalysts exhibited the best catalytic performance (83.3% yield of tetrahydrofurfuryl alcohol) under the optimized conditions of 30 bar hydrogen and 5 h, at 100 and 130 °C, respectively. Synergistic effect of bimetallic catalysts has been utilized to improve catalytic activity and stability. The extremely active for the selective hydrogenation of furfural over Pt–Fe/MWNT and Pd–Ni/MWNT catalyst might be attributed to active crystal planes exposed over Pt and Pd promoted by Fe and Ni. Catalysts have shown stable activity and selectivity after 5 cycles using Pt–Fe/MWNT and Pd–Ni/MWNT catalysts. Moreover, we suggest that acid sites of conventional supports might have an impact on furfural conversion.
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RSC Advances
·
2015
·Vol. 5
·期 75
·60775-60785
·
IF 3.84
Xin Ran,Long Yang,Genfu Zhao,Hanzhang Ye,Yanqiong Zhang,Shuangmei Fan,Xiaoguang Xie,Hui Zhao,Can-Peng Li
In the present work, ultrafine Pd clusters with a uniform size of ∼2.0 nm were monodispersed on the surface of reduced graphene oxide (RGO) using a clean and green approach in the absence of additional reductants and surfactants. Disulfide linked β-cyclodextrin dimer (SS-β-CD) was non-covalently bonded to the surface of Pd@RGO. By combining the merits of Pd@RGO and the SS-β-CD, a highly sensitive electrochemical sensing platform was developed based on the SS-β-CD–Pd@RGO nanohybrids. Simultaneous electrochemical detection of baicalin and luteolin using a SS-β-CD–Pd@RGO nanohybrid-modified electrode is described for the first time. The SS-β-CD showed a higher supramolecular recognition capability than the native β-CD, which may be caused by the cooperative binding abilities of two adjacent CD units. Due to the synergistic effects from the Pd@RGO (e.g. good electrochemical properties and large surface area) and SS-β-CD (e.g. hydrophilic external surface, high supramolecular recognition, and good enrichment capability), the SS-β-CD–Pd@RGO modified electrode was found to have linear response ranges of 0.02–20.00 μM for baicalin and 0.01–10.00 μM for luteolin with relatively low detection limits of 0.0052 μM for baicalin and 0.0070 μM for luteolin. The results indicated that SS-β-CD–Pd@RGO nanohybrids are excellent sensing materials for the electrochemical determination of flavonoids. The proposed method could be successfully utilized to detect baicalin and luteolin in serum samples, and has a promising application in practice.
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CATALYSIS LETTERS
·
2012
·Vol. 143
·期 2
·200-205
·
IF 2.242
Zeng Yan,Wang Yanhua,Xu Yicheng,Song Ying,Jiang Jingyang,Jin Zilin
Abstract A thermoregulated ionic liquid and organic biphasic system composed of ionic liquid [CH 3 (OCH 2 CH 2 ) 16 N + Et 3 ][CH 3 SO 3
− ] (IL PEG750 ) with IL PEG750 -stabilized Pd nanoparticles and organic solvents, which allows for not only a highly efficient homogeneous catalytic reaction, but also an easy biphasic separation and reuse of catalyst attributed to the thermoregulated phase-transition property of the system, was employed for Heck reaction. The IL PEG750 -stabilized Pd nanoparticle catalyst exhibited high efficiency, more importantly, after reaction the Pd nanoparticle catalyst could be separated from products by simple phase separation and recycled for six times without evident loss of activity. Graphical Abstract A thermoregulated ionic liquid and organic biphasic system containing [CH 3 (OCH 2 CH 2 ) 16 N + Et 3 ][CH 3 SO
- 3
] (IL PEG750 )-stabilized Pd nanoparticles was applied to Heck reaction for the first time. The Pd nanoparticle catalyst exhibited high efficiency and good recyclability.
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CHEMICAL ENGINEERING JOURNAL
·
2015
·
IF 4.321
Chen Sun,Zimo Lou,Yu Liu,Ruiqi Fu,Xiaoxin Zhou,Zhen Zhang,Shams Ali Baig,Xinhua Xu
In this study, nanosized titanium nitride (nTiN) doped palladium/nickel (Pd/Ni) foam electrodes were prepared via electroless deposition method for the dechlorination of 2,4-dichlorophenoxyacetic acid (2,4-D). Characterization analyses including field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM) revealed that nTiN was successfully doped onto the electrode surface. 2,4-D was first dechlorinated to intermediate products p -chlorophenoxyacetic acid ( p -CPA) or o -chlorophenoxyacetic acid ( o -CPA) and then to the final product, phenoxyacetic acid (PA). The effects of environmental factors including initial 2,4-D concentration, current density, reaction temperature and dissolved anions were also studied. High initial 2,4-D concentration increased the efficient utilization of active hydrogen atom [H] by nTiN doped Pd/Ni foam electrodes. Increases in current density promoted better dechlorination efficiency while the hydrogen evolution side reaction was undesirably increased, leading to a lower average current efficiency. Higher reaction temperature was proved to be favorable for the enhancement of dechlorination efficiency. NO 3 − and reduced sulfur compounds including S 2− and SO 3 2− showed negative impacts on Pd catalytic capability, whereas CO 3 2− and Cl − exhibited less adverse effects on dechlorination efficiency. The activation energy ( E a) value of 2,4-D dechlorination by nTiN doped Pd/Ni foam electrode was calculated to be 32.06 kJ mol −1 . Two typical stages namely electrode activation and efficient dechlorination procedures occurred in 2,4-D dechlorination by nTiN doped Pd/Ni foam electrodes. The reaction paths of [H] on the electrode were also summarized. The removal efficiency of 2,4-D dechlorination on nTiN doped Pd/Ni foam electrodes was observed to slightly decrease from 100% to 89.95% after 5 consecutive experiments.
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RSC Advances
·
2014
·Vol. 4
·期 95
·52640-52646
·
IF 3.708
Qian-Li Zhang,Jin-Xia Feng,Ai-Jun Wang,Jie Wei,Jiu-Ju Feng
Bimetallic alloyed Pd–Au nanochain networks supported on reduced graphene oxide (Pd–Au NNs/RGO) were prepared by a one-pot wet-chemical co-reduction method with the assistance of caffeine as a capping agent and a structure directing agent, while no seed, template, or surfactant was involved. It was found that the dosage of caffeine and the concentrations of the precursors (i.e. PdCl42− + AuCl4−) played essential roles in the formation of Pd–Au NNs. Moreover, the as-prepared nanocomposites exhibited much better electrocatalytic performance than those of conventional Pd black and Pd–C toward oxygen reduction reaction (ORR) in alkaline media in terms of the onset potential, limiting current, and stability.
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ACS Catalysis
·
2015
·
IF 9.312
Jingyi Hu,Qiwei Yang,Lifeng Yang,Zhiguo Zhang,Baogen Su,Zongbi Bao,Qilong Ren,Huabin Xing,Sheng Dai
Metal catalysts often encounter the dilemma of rapid deactivation due to reduction or particle aggregation/growth during the reaction. Here we reported an active and stable metal nanoparticles (NPs)/surfactant ionic liquid (IL) system for the catalytic hydrochlorination of acetylene. The NPs of Pd, Au, and Pt with a narrow size distribution and well-defined lattice fringes experienced in situ generation in the reaction medium of anionic surfactant carboxylate ILs (ASC-ILs). Benefiting from the high reactivity of NPs and the self-assembly property of ASC-ILs, an effective redox cycle between Pd0 and PdII was established to reduce the deactivation of metal catalysts. The Pd NPs/surfactant IL systems showed excellent catalytic activity toward acetylene hydrochlorination. An acetylene conversion of 93% and a selectivity of 99.5% were achieved with no discernible deterioration over a reaction time of 55 h. Furthermore, ASC-ILs were endowed with a unique property of the strong hydrogen-bond basicity, which was effective in absorbing and activating acetylene and HCl. This study manifests that metal NPs/surfactant IL systems are promising as substitutes for toxic mercury catalysts in the hydrochlorination of acetylene, and also is instructive for the stabilization of metal NPs.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2014
·
IF 2.93
Shan-Shan Li,Yuan-Yuan Hu,Jiu-Ju Feng,Zhang-Ying Lv,Jian-Rong Chen,Ai-Jun Wang
In this paper, a simple, fast, and green method is developed for preparation of uniform Pd nanodendrites anchored on reduced graphene oxide (Pd/RGO) at room temperature , with the assistance of octylphenoxypolye thoxyethanol (NP-40) as a soft template, while no seed, organic solvent , or special apparatus involved. The as-prepared nanocomposites show the improved CO tolerance, enhanced catalytic activity , and better stability for ethylene glycol (EG) and glycerol (Gly) electrooxidation in alkaline media , compared with commercial Pd black and Pd/C catalysts. The synthetic strategy can be extended to fabricate other electrocatalysts in direct alcohol fuel cells .
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2014
·
IF 2.235
Lu Lin,Tong Zhang,Xiongfu Zhang,Haiou Liu,King Lun Yeung,Jieshan Qiu
In this work, we fabricated a new type of Pd/SiO2@ZIF-8 core–shell catalyst composed of a Pd/SiO2 microsphere as the core and a ZIF-8 membrane as the shell. The preparation procedure involves first loading Pd nanoparticles onto nonporous SiO2 microspheres to obtain the Pd/SiO2 core and then coating a perfect layer of ZIF-8 shell on the core by electrostatic induction to form a Pd/SiO2@ZIF-8 core–shell structure. It is crucial that the modification of the Pd/SiO2 core with polyelectrolyte was employed to improve the charge distribution of the core surface and preferably adsorb Zn2+ cations in the synthesis solution so as to assist the formation of a continuous ZIF-8 shell. The compactness and thickness of the shell were optimized by increasing the number of cycles of ZIF-8 growth. The hydrogenations of alkenes with different molecular sizes showed that the Pd/SiO2@ZIF-8 catalysts can provide excellent product selectivity and antipoisoning and antileaching properties for the hydrogenations of alkenes.
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