JOURNAL OF ORGANIC CHEMISTRY
·
2021
·
IF 4.354
Junhua Kong,Zhi-Jiang Jiang,Jiayuan Xu,Yan Li,Hong Cao,Yanan Ding,Bencan Tang,Jia Chen,Zhanghua Gao
A practical and scalable ortho-selective deuteration of aromatic aldehydes was accomplished by Pd-catalyzed hydrogen isotope exchange with deuterium oxide as an inexpensive deuterium source. The use of tert-leucine as a transient directing group facilitates the exchange, affording a wide range of ortho-deuterated aromatic aldehydes with deuterium incorporation up to 97%. The control experiments suggest that the addition of silver trifluoroacetate resists the unexpected reduction of Pd(II), while the theoretical study indicates a rapid reversible concerted metalation–deprotonation process.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
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IF 13.273
Zichen Zhang,Hengjun Gai,Qun Li,Bingxiao Feng,Meng Xiao,Tingting Huang,Hongbing Song
In this work, N-rich ionic liquid based on 1,3,5-triimidazole triazine was used to construct poly(ionic liquid) (PIL) through free radical polymerization, and support palladium nanoparticles (Pd NPs), which were used in the catalytic hydrogenation of nitrobenzene. The resulting N-rich PIL had a good dispersion effect and ultrafine Pd NPs as shown by SEM and TEM, thereby significantly enhancing the stability of the loaded metal NPs. The XPS results indicated that the metal-support interaction improved the catalytic performance of the catalyst. In particular, the effects of different anions (Tf 2 N - , PF 6 - , and Cl - ) on the PILs were investigated, and the results showed that the Tf 2 N anion exhibited the best catalytic effect on the hydrogenation of nitrobenzene. Furthermore, density functional theory calculation confirmed that anions played a key role in activating the substrate in the hydrogenation of nitrobenzene. The corresponding results were consistent with the experimental results, which provided reference and research for the application of PILs in the future.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2019
·
IF 14.229
Ming Lei,Zhiying Wang,Lihua Zhu,Wenshan Nie,Heqing Tang
Deep debromination of polybrominated diphenyl ethers (PBDEs) by visible light photocatalysis is still a challenge in the field of halogenated pollutants control. Here, an efficient photocatalyst (Pd/g-C 3 N 4 ) was prepared by a simple impregnation-chemical reduction method with bulk g-C 3 N 4 and PdCl 2 as precursors. Under preferred reaction conditions (visible light irradiation for 120 min), the use of the 0.5% Pd/g-C 3 N 4 composites (0.4 g L −1 ) yielded an almost complete debromination of BDE47 (10 μmol L −1 ) in methanol-water mixture, while the debromination of BDE47 did not occur on pure g-C 3 N 4 . A “Pd-promoted active H atom species attack and C-Br bond cleavage” route was proposed according to the identified degradation intermediates. A catalytic mechanism was further clarified: Pd nanoparticles exerted affinity interaction with bromine atoms, and the storing of electrons on Pd would increase the binding interaction. In the debromination process, methanol acts as both a hole scavenger and a hydrogen donor to provide active H atom species through the reaction of H + and photogenerated electrons on Pd nanoparticles. The initiation of BDE47 debromination on Pd nanoparticles required an induction period to enrich a critical amount of electrons for stretching the C-Br bond and its subsequent being attacked by active H atoms. The generated 2,2′-dibromodiphenyl ether (BDE4) would be further reduced to bromine-free products by hydro-debromination process or coupling reaction.
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ACS Applied Materials & Interfaces
·
2019
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IF 8.456
Tong Wu,Yu Ma,Zhibei Qu,Jinchen Fan,Qiaoxia Li,Penghui Shi,Qunjie Xu,Yulin Min
Rational design supporting material for palladium (Pd)-based catalyst can maximize its electrocatalytic performance for ethanol oxidation reaction (EOR) catalyst in alkaline condition. Utilizing the unique two-dimensional structures and outstanding physicochemical property of graphene and black phosphorus (BP), herein, we proposed and designed a black phosphorus–graphene heterostructure for supporting Pd nanoparticles. Through merely ball-milling of activated graphene (AG) and black phosphorus (BP), the AG–BP hybrid with a linkage of P–C bonding is used as supports of Pd. The obtained Pd/AG–BP hybrid exhibits ultrahigh electrochemical activity toward EOR. Remarkably, it can achieve a high mass peak current density of ∼6004.53 and ∼712.03 mA mgPd–1 before and after the durability tests of 20 000s on EOR, which are ∼7.19 and 80 times higher than those of commercial Pd/C. The experimental analysis and density-functional-theory calculation show that Pd becomes more positive with electrons transfer from Pd to AG–BP supports and is liable to absorb the OH radicals for removing COads intermediate to release active sites on EOR, together with the excellent ability to generate additional OH militants after combining with the AG–BP heterostructure.
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APPLIED ORGANOMETALLIC CHEMISTRY
·
2019
·Vol. 33
·期 5
·e4850
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IF 3.259
Mingliang Ma,Yuying Yang,Yanyan Liu,Wenting Li,Guopeng Chen,Yong Ma,Ping Lyu,Shunhe Li,Yubao Wang,Guanglei Wu
In this paper, a simple route for palladium (Pd) nanoparticles attached to the surface of hollow magnetic Fe 3 O 4 /P (GMA-DVB)-polyethyleneimine (PEI) microspheres was established. Due to the large amount of imidogen groups and tertiary amine groups presenting in the PEI, Pd 2+ ions could be anchored to the support by complexation with a polyfunctional organic ligand. Thereafter, a magnetic Pd catalyst having a high loading amount and good dispersibility was obtained by reducing Pd 2+ ions. Afterwards, the prepared catalyst was characterized by TEM, SEM, FTIR, XRD, TGA, VSM, and UV–vis in detail. Ultimately, their catalytic activity was evaluated using the reduction of 4-nitrophenol (4-NP). Research showed that the Fe 3 O 4 /P (GMA-DVB)-PEI/Pd catalyst possessed high catalytic performances for the reduction of 4-NP with a conversion rate of 98.43% within 540 s. Furthermore, the catalyst could be easily recovered and reused at least for nine successive cycles.
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ACS Sustainable Chemistry & Engineering
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2019
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IF 6.97
Rifeng Wu,Yanjie Li,Wenhao Gong,Pei Kang Shen
One-pot synthesis Pt–Pd bimetallic nanostructure has become a promising way to get superior oxygen reduction reaction performance and cost-effective electrocatalyst for proton exchange membrane fuel cells. In this work, we report a facile one-pot method by tuning the feed ratio of Pt and Pd (Pt3Pd1, Pt2Pd1, and Pt1Pd1) in ethylene glycol solution at the effect of iodide ions and poly(vinylpyrrolidone) to synthesize three different Pt–Pd bimetallic nanodendrites structure. Transmission electron microscopy and high-resolution transmission electron microscopy revealed that the nanodendrites have a Pt-rich surface structure and numerous high-index facets at the branch’s surface, thus providing a great deal of catalytic sites. Carbon-supported Pt–Pd nanodendrite catalysts were investigated for oxygen reduction reaction performance and accelerated durability test. The Pt1Pd1/C catalyst shows the best activity and durability and with a mass activity of 1.164 A mgPt–1 and a specific activity of 1.33 mA cm–2, greatly enhanced compared with commercial TKK-Pt/C catalysts (0.15 A mgPt–1 for mass activity, and 0.25 mA cm–2 for a specific activity). The Pt1Pd1/C catalyst also exhibits remarkable durability with almost negligible decay in performance after 10 000 cycles. These results provide us an attractive strategy for designing catalysts with a simple route, lower cost, and remarkable catalytic activity and durability.
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Journal of CO2 Utilization
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2019
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IF 5.189
Haoxi Jiang,Qiang Gao,Shutian Wang,Yifei Chen,Minhua Zhang
Carbon dioxide methanation is of great importance for both environment and energy because of the reduction of carbon dioxide emissions and the utilization of carbon source. In this work, UiO-66 was employed as the support for palladium nanoparticles via a sol-gel method to enhance the activity of CO 2 methanation. The physical-chemical properties of as-prepared catalysts were characterized using N 2 adsorption-desorption, X-ray diffraction (XRD), transmission electron microscope (TEM), temperature programmed desorption (TPD), temperature programmed reduction (TPR), thermo-gravimetric analysis (TGA), Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that there was a synergistic effect between UiO-66 and supported Pd. CO 2 could be activated in UiO-66 via its Zr 6 O 4 (OH) 4 nods, while H 2 molecules were dissociated at Pd for further hydrogenation of activated CO 2 . As a result, the catalyst with a Pd loading of 6 wt.% exhibited a high activity with 56.0% of CO 2 conversion and 97.3% of CH 4 selectivity, corresponding to a STY of 856 g·h −1 ·kg cat −1 at 4 MPa and 340 °C.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2019
·
IF 4.182
Ruyue Niu,Pengcheng Liu,Wei Li,Shuang Wang,Jinping Li
0.123%Pd encapsulated in nanosized silicalite-1 (MFI) zeolite catalysts has been prepared by direct hydrothermal conditions, and its catalytic performance at the low concentration methane combustion was studied. The temperatures for methane ignition ( T 10% ), the half-conversion temperature ( T 50% ) and the total conversion temperature ( T 90% ) over Pd/S-1-in (in-situ method) catalyst are 261, 329 and 382 °C, respectively, which are lower than the corresponding temperatures of Pd/S-1-im (incipient impregnation method) catalyst. Moreover, the properties are further enhanced by introducing CeO 2 into the Pd/S-1-in catalyst. The conversion rate decreased slightly from 91 to 85% when the reaction is carried out at 450 °C for 100 h at the gas hourly space velocities (GHSV) of 112500 mL g −1 h −1 . The XPS analysis showed that Pd clusters were encapsulated within the porous rather than on the surface of the crystal by in-situ method. The HRTEM studies demonstrated that the Pd particle encapsulated within Silicalite-1 zeolites are well dispersed and evenly distributed throughout the Silicalite-1 zeolites. The average size of in situ Pd particle encapsulated in Silicalite-1 zeolite is 1.7 nm, which is much smaller than the impregnated Pd/S-1-im catalyst (2.8 nm).
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NANO
·
2019
·
IF 1.293
Shaozhen Wang,Biao Zang,Qiang Zhang,Hui Zhang,Liping Qu,Hongqi Chen
This paper reports a surfactant-free synthesis of clean-surface dendritic Pd nanostructures. The key of this synthetic strategy was using ethanol as a reductant to directly reduce Pd(OH) 2 . In terms of electrocatalytic methanol oxidation in alkaline media, the clean-surface and self-supported Pd nanostructures are beneficial to a high catalytic performance, including superior electrocatalytic activity and stability. The as-prepared dendritic Pd shows 2.57 and 4.39 times higher specific activity than palladium nanoparticles and a commercial Pd/C catalyst, respectively. Furthermore, we demonstrated that the clean-surface nanoparticles exhibit higher performance than that of the surfactant-capped Pd nanostructures for methanol electro-oxidation. Therefore, the dendritic Pd nanostructures are potential candidates as the efficient electrode material in fuel cells.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2018
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IF 11.698
Yazhi Yin,Bing Hu,Xinliang Li,Xiaohai Zhou,Xinlin Hong,Guoliang Liu
Direct CO 2 hydrogenation to methanol provides a means of CO 2 fixation and a way of hydrogen storage in a more energy-dense and transportable form. Pd-ZnO catalysts can be active for this reaction, but their activities are strongly associated with the preparation methods which influence the dispersion and stability of Pd nanoparticle. Here we report a novel fabrication of highly effective PdZn alloy catalysts derived from Pd@zeolitic imidazolate framework (ZIF-8) for the hydrogenation of CO 2 . The confinement of subnanometric Pd particles in the pore framework of ZIF-8 facilitates the formation of Pd-ZnO interfaces with strong-metal-support-interaction (SMSI) after a simple pyrolysis under air condition. The porous texture and high surface area of ZnO ensures a high dispersion of Pd nanoparticles. Different pyrolysis temperatures were studied in catalysis and the highest methanol yield reached 0.65 g g cat −1 h −1 at 270 °C, 4.5 MPa, with a TOF of 972 h −1 , over a PdZn catalyst prepared at 400 °C. Such excellent activity has ranked the top reported values over advanced Pd-based catalysts under comparable conditions. The crucial factors for such high methanol yield are the formation of small-sized PdZn alloy particles after H 2 reduction and abundant surface oxygen defects on ZnO. The SMSI between PdZn and ZnO also ensures a long term stability of our PdZn catalysts. At last, we propose the active site that was strongly associated with methanol formation is a PdZn alloy rather than metallic Pd.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2018
·
IF 3.649
Qingqing Ma,Nan Wang,Guozhu Liu,Li Wang
Pd catalysts on mesoporous silica SBA-15 functionalized with alkyltriethoxysilane (alkyl = methyl, ethyl, propyl and isobutyl) were prepared. The effects of grafting sequence on the grafting amount were studied. The catalysts were characterized by XRD , FT-IR, elemental analysis , thermogravimetric analysis , nitrogen adsorption-desorption, TEM and XPS , and evaluated using catalytic hydrogenation of 2-ethyl-anthraquinone. The grafting amount increases with increasing the alkyl chain length of alkyltriethoxysilane. The highest grafting amount with the carbon content of 1.56% is obtained using an ante-grafting procedure where the grafting is performed prior to the removal of template, and this catalyst shows the highest activity and selectivity (98.3%). The accordant relationship between the activity of Pd/SBA-15 catalysts and their grafting amount indicates a positive effect of hydrophobicity of SBA-15 created by grafting on the catalytic hydrogenation of 2-ethyl-anthraquinone.
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CHEMICAL ENGINEERING JOURNAL
·
2018
·
IF 6.735
Rongrong Li,Wubing Yao,Yanxian Jin,Wenping Jia,Xiaoying Chen,Jingjing Chen,Jianli Zheng,Yuan Hu,Deman Han,Jia Zhao
Hydrocinnamaldehyde (HCAL) is a crucial intermediate in the manufacture of perfumes and pharmaceuticals, but highly selective hydrogenation of cinnamaldehyde (CALD) to hydrocinnamaldehyde with a good conversion rate is a challenging. We report that the incorporation of Ag into Pd-based catalysts promotes their catalytic activity and HCAL selectivity (HCAL selectivity of 98.6% with >99.9% CALD conversion for Pd-0.3Ag/MCM-41) for CALD hydrogenation compared to those of catalysts with no Ag, e.g., HCAL selectivity of 84.5% for Pd/MCM-41and 77.3% for Pd/AC (activated carbon). The Pd-0.3Ag/MCM-41 catalyst shows an outstanding stability during five cycles of use. The excellent performance of the Pd-0.3Ag/MCM-41 catalyst in CALD hydrogenation is due to the ultra-small size of the Pd nanoparticles (Pd-Ag alloy, a geometric and electronic modification of Pd).
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