BIORESOURCE TECHNOLOGY
·
2014
·
IF 5.039
Riyang Shu,Jinxing Long,Zhengqiu Yuan,Qi Zhang,Tiejun Wang,Chenguang Wang,Longlong Ma
An efficient lignin depolymerization process with highly controllable product distribution was presented using metal chloride (MCl x ) cooperated with Pd/C. The catalytic performances of MCl x were investigated. The effect of reaction conditions on the lignin depolymerization and products distribution were also studied. Results showed that more than 35.4% yield of phenolic monomer including 7.8% phenols and 1.1% guaiacols could be obtained under optimized condition. And the product distribution can be efficiently controlled by the modification of the metal cation through different pathway of Lewis acid catalysis and coordination catalysis. Furthermore, the Pd/C catalyst showed an excellent recyclability, where no significant loss of the catalytic activity was exhibited after 3 runs. Moreover, the product control mechanism was proposed.
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PubMed
高影响因子
Energy Technology
·
2016
·Vol. 4
·期 8
·943-949
·
IF 2.557
Dong Pi,Wen Zhi Li,Qi Zhao Lin,Qi Fu Huang,Hui Qing Hu,Chun Yu Shao
A series of Pd-based core–shell catalysts (Pd@SiO 2 , Pd@CeO 2 , and Pd@ZrO 2 ) supported on Si-modified Al 2 O 3 were prepared for the catalytic combustion of lean methane. Pd@SiO 2 exhibited slightly lower catalytic activity than Pd@CeO 2 and higher catalytic activity than Pd@ZrO 2 in dry conditions; however, Pd@SiO 2 had the highest catalytic activity among the three catalysts in the presence of high concentrations of water vapor. Furthermore, the Pd@SiO 2 catalyst showed good thermal stability and resistivity to water poisoning. CO chemisorption and TEM results demonstrated that the core–shell structure could help in the stabilization of the active phase compared to the uncoated Pd/Si-Al 2 O 3 catalyst. XRD and X-ray photoelectron spectroscopy results indicated that a balanced mixed phase of PdO x /Pd 0 is the main active phase of these Pd-based catalysts.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2017
·
IF 5.401
Li Xiao,Shengrui Xu,Geng Yu,Shantang Liu
A novel gas microsensor combining SnO 2 submicron/nanostructured porous sensitive film with Micro-Electro-Mechanical systems (MEMS) microheater was successfully fabricated. The film was made of hierarchically mixed Pd/SnO 2 (HM-PTO) composites composed of Pd/SnO 2 hollow submicrospheres (Pd/SnO 2 -HSs) and Pd/SnO 2 nanoparticles (Pd/SnO 2 -NPs) deposited on the microheater platform using the microdispensing method. The as-prepared HM-PTO sensors exhibited high sensitivities, fast response/recovery rates, good selectivity, reliable reversibility, and relevant stability towards ethanol at low power consumption. The resulting superior sensing performances were attributed to the unique hierarchical structure. The internal void architecture of Pd/SnO 2 -HSs provided large specific surface areas, proper mesopore size distribution, large number of active adsorption/interaction sites, as well as promoted the chemisorption and dissociation of gas molecules due Pd-doping to yield superior gas response. In particular, the nano-sized SnO 2 particles ensured the uniform deposition of the materials to yield enhanced local conductivities, and possibly faster phase transfer reactions responsible for the extremely good response/recovery performance. This simple fabrication procedure combined with high sensing performances look promising for the development of hierarchical morphologies of novel materials for gas sensing applications.
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JOURNAL OF NANOPARTICLE RESEARCH
·
2017
·Vol. 19
·期 5
·1-8
·
IF 2.02
Zhao Haiqiang,Qi Weihong,Ji Wenhai,Wang Tianran,Peng Hongcheng,Wang Qi,Jia Yanlin,He Jieting
Fivefold symmetry appears only in small particles and quasicrystals because internal stress in the particles increases with the particle size. However, a typical Marks decahedron with five re-entrant grooves located at the ends of the twin boundaries can further reduce the strain energy. During hydrothermal synthesis, it is difficult to stir the reaction solution contained in a digestion high-pressure tank because of the relatively small size and high-temperature and high-pressure sealed environment. In this work, we optimized a hydrothermal reaction system by replacing the conventional drying oven with a homogeneous reactor to shift the original static reaction solution into a full mixing state. Large Marks-decahedral Pd nanoparticles (~90 nm) have been successfully synthesized in the optimized hydrothermal synthesis system. Additionally, in the products, round Marks-decahedral Pd particles were also found for the first time. While it remains a challenge to understand the growth mechanism of the fivefold twinned structure, we proposed a plausible growth-mediated mechanism for Marks-decahedral Pd nanoparticles based on observations of the synthesis process.
This is a stepwise growth mechanism for Marks-decahedral Pd nanoparticles. First, many truncated tetrahedrons are formed. Then, two adjacent {111} facets of a truncated single tetrahedron simultaneously grow epitaxially, forming a truncated tri-tetrahedron. A Marks decahedron is formed directly by epitaxial growth of both concave {111} facets of a truncated tri-tetrahedron.
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Journal of CO2 Utilization
·
2016
·
IF 4.764
Xiying Fu,Dagang Zhou,Kai Wang,Huanwang Jing
Pd/C was found to be an excellent catalyst in the coupling reaction of carbon dioxide and epoxides with tetrabutylammonium iodide (TBAI) as cocatalyst and the corresponding cyclic carbonates were obtained in good yields and high selectivities. 3-Chloropropylene carbonate was synthesized under extremely mild conditions of room temperature and atmosphere. The proposed mechanism was also calculated and confirmed by DFT. The palladium catalyst could be simply recycled and reused for 5 times without significant loss of activity.
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ACS Catalysis
·
2016
·
IF 9.307
Da Lei,Kai Yu,Meng-Ru Li,Yuling Wang,Qi Wang,Tong Liu,Pengkun Liu,Lan-Lan Lou,Guichang Wang,Shuangxi Liu
Single-crystalline Pd nanocrystals enclosed by {111} or {100} facets with controllable sizes were synthesized and originally employed as catalysts in the aerobic oxidation of 5-hydroxymethyl-2-furfural (HMF). The experimental results indicated that the particle size and exposed facet of Pd nanocrystals could obviously influence their catalytic performance. The size-dependent effect of Pd nanocrystals in this reaction could only be derived from the different Pd dispersions. Therefore, the facet effect of Pd nanocrystals was first investigated in this work through experimental and theoretical approaches. It was found that Pd-NOs enclosed by {111} facets were more efficient than Pd-NCs enclosed by {100} facets for the aerobic oxidation of HMF, especially for the oxidation step from 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) toward 5-formyl-2-furancarboxylic acid (FFCA). The TOF value of Pd-NOs(6 nm) was 2.6 times as high as that of Pd-NCs(7 nm) and 5.2 times higher than that of commercial Pd/C catalyst for HMF oxidation. Through density functional theory (DFT) calculations, the notably enhanced catalytic performance of Pd-NOs could be mainly attributed to the lower energy barrier in the alcohol oxidation step (from HMFCA to FFCA) and higher selectivity for O2 hydrogenation to produce peroxide.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2016
·
IF 3.205
Peng Zhou,Dongzhi Li,Shiwei Jin,Shaohua Chen,Zehui Zhang
The hydrogenation of nitro compounds into amines is of great importance both from academic and industrial points. In this study, graphene oxide was simultaneously decorated by Fe 3 O 4 and Pd nanoparticles to generate magnetic C–Fe 3 O 4 –Pd catalyst, which showed high catalytic activity towards the transfer hydrogenation of nitro compounds by the use of NaBH 4 as the hydrogen donor at room temperature . Aniline was produced in a high yield of 99% after 30 min at 25 °C. A wide variety of substituted nitroarenes with other reducible groups were also successfully converted into the corresponding amines with high yields. Kinetic studies revealed the active energy of the transfer hydrogenation of nitrobenzene was 31.1 kJ mol −1 . One of the main reasons of the high catalytic activity of the C–Fe 3 O 4 –Pd catalyst was due to the fact that the catalyst showed high ability to absorb the substrate on its surface. 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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JOURNAL OF POWER SOURCES
·
2016
·
IF 6.333
Geng Zhang,Wangting Lu,Longsheng Cao,Xiaoping Qin,Fei Ding,Shun Tang,Zhi-Gang Shao,Baolian Yi
The reduction of Pt content together with the improvement of the durability of the catalyst for oxygen reduction reaction (ORR) is required to the large-scale commercialization of proton exchange membrane fuel cells. In this work, a novel ORR catalyst consisting of large Pd nanocrystal as the core with small Pt nanoparticles supported on the Pd core is prepared by a facile one-step synthesis method . The Pd substrate is presented in the form of well-defined cuboctahedrons and icosahedrons. The type of metal precursors and Pt/Pd molar ratio are important factors to obtain this Pd-supporting-Pt structure. The Pd 2 -s-Pt 1 catalyst with a nominal Pt/Pd atomic ratio at 1/2 shows improved ORR activity: its mass specific activity and area specific activity is 2.5 and 3.5 times that of commercial Pt/C, respectively. More importantly, the Pd 2 -s-Pt 1 catalyst demonstrates outstanding durability against potential cycling which can be ascribed to the slow dissolution of Pd core and the structure transformation from Pd@Pt to hollow PdPt alloyed nanocages . This exciting result provides a new pathway to the design of ORR catalyst with excellent durability.
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JOURNAL OF MATERIALS SCIENCE
·
2016
·Vol. 51
·期 18
·8502-8515
·
IF 2.302
Ran Junhui,Wang Haiying,Cheng Xinjian
Fluorescent chemosensors based on silica nanoparticles and silicate glass slides were well designed and prepared. The as-prepared fluorescent silica particles and glass slides exhibited highly selective sensing and absorbing abilities to Pd 2+ ions in aqueous phase. SiO 2 nanoparticles were first synthesized by the hydrolysis of tetraethyl orthosilicate (TEOS), and then –NH 2 groups were introduced to silica by treating with 3-aminopropyltriethoxysilane (APTES). Subsequently, 4-amino-1,8-naphthalic anhydride (ANA) was incorporated with the reaction of –NH 2 groups. Finally, salicylaldehyde (SA) was introduced by the reaction between amino groups in ANA and the –CHO groups in SA. Thus, the fluorescent silica nanoparticles were obtained. This method was expanded to prepare fluorescent silicate glass slides. Upon the addition of Pd 2+ ions, the fluorescence quenched immediately. These chemosensors were selectively sensitive to Pd 2+ ions as low as 10 μM. The absorption efficiency of fluorescent nanoparticles and glass slides for Pd 2+ reached to 38.38 and 27.50 %, respectively. And the chemosensors also could be easily recycled and reused for at least five times. Fluorescent silica nanoparticles with only ANA or SA (not ANA and SA together) also exhibited the sensing ability to Pd 2+ ions; however, it showed the shortage of Pd 2+ ions selectivity. It suggested that it is necessary to introduce both ANA and SA for the high sensitivity and selectivity to Pd 2+ ions.
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LANGMUIR
·
2016
·
IF 3.993
Yingzhou Tao,Anirban Dandapat,Liming Chen,Youju Huang,Yoel Sasson,Zhenyu Lin,Jiawei Zhang,Longhua Guo,Tao Chen
We report a very easy and effective approach for synthesizing unique palladium-on-gold supra-nanostructure (Au@Pd-SprNS)-decorated graphene oxide (GO) nanosheets. The SprNSs comprising Au nanorods as core and a unique close-packed assembly of tiny anisotropic Pd nanoparticles (NPs) as shell were homogeneously distributed on the GO surface via electrostatic self-assembly. Compared with the traditional one-pot method for synthesis of metal NPs on GO sheets, the size and shape of core–shell Au@Pd SprNSs can be finely controlled and uniformly distributed on the GO carrier. Interestingly, this Au@Pd-SprNSs/GO nanocomposite displayed high electrocatalytic activities toward the oxidation of methanol, ethanol, and formic acid, which can be attributed to the abundance of intrinsic active sites including high density of atomic steps, ledges and kinks, Au–Pd heterojunctions and cooperative action of the two metals of the SprNSs. Additionally, uniform dispersion of the SprNSs over the GO nanosheets prevent agglomeration between the SprNSs, which is of great significance to enhance the long-term stability of catalyst. This work will introduce a highly efficient Pd-based nanoelectrocatalyst to be used in fuel cell application.
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ACS Omega
·
2016
·
IF 0
Zhiyi Wu,Qiangqiang Zhu,Chun Shen,Tianwei Tan
Aimed at the green synthesis of supported noble metal nanoparticles without any additional reducing agents or stabilizers at room temperature, a new strategy in which monodispersed Pd nanoparticles were successfully immobilized on Mg–Al mixed metal oxides derived from layered double hydroxides was developed, and the reduction mechanism was also proposed. It allowed the in situ immobilization of monodispersed Pd nanoparticles with a face-centered cubic structure, using only alcohols with α-hydrogen atom as the solvent and reducing agent. Control over the mean particle size and content of Pd nanoparticles was realized by adjusting the temperature, initial concentration, and type of alcohol. With the content of Pd varied from 6.4 to 42.3 mg/g, the mean particle size of Pd increased from 1.1 to 4.9 nm. The as-prepared catalyst showed high catalytic activity for oxidation of benzyl alcohol: when the Pd content was 6.4 mg/g, conversion of 60.3% and selectivity of 99.2% were obtained with a turnover frequency of 4807 h–1. Similarly, on the basis of the high stand electrode potentials, immobilized Ag (5.6 nm) and Au (4.7 nm) nanoparticles were also prepared through this methodology. Moreover, the choice of supports was extended to other powder supports that would react with the byproduced acid. Overall, this facile method opens up new opportunities for controllable synthesis of supported nanoparticle catalysts in a green way.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2016
·
IF 3.205
Wen-da Zhong,Xi-ke Tian,Chao Yang,Zhao-xin Zhou,Xiang-wen Liu,Yong Li
In this work, a novel three dimensional (3D) Pd/graphene aerogel hybrid was successfully synthesized and characterized. The preparation process of the Pd/graphene aerogel was also discussed systematically. Experimental results indicated that this kind of 3D Pd/graphene aerogel hybrid exhibited excellent catalytic activity on the ammonia borane hydrolysis to release hydrogen with the turnover frequency value of 9.70 mo l H 2 mo l metal − 1 mi n − 1 , and activation energy E a value of 30.82 kJ/mol, which is higher than that of 2D Pd/RGO and original Pd nanoparticles . Furthermore, the abundant defects of graphene aerogel support can transfer the electrons of Pd nanoparticles to graphene aerogel due to the metal-support interaction, which is beneficial to the ammonia borane hydrolysis reaction . In addition, the pore-rich 3D Pd/graphene aerogel has offered huge effective reacting acreages for ammonia borane hydrolysis, which is helpful for its reusability .
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