Yanhui Yang

Xiamen University, Amoy, Fujian, China

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Publications (127)593.32 Total impact

  • Source
    Applied Catalysis B Environmental 01/2015; 162:401–411. · 6.01 Impact Factor
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    ABSTRACT: A series of bimetallic catalysts Au-M (M = Cu, Co, Ru, Pd and Ni) were supported on TiO2 via deposition-precipitation (DP) method using urea as precipitating agent. The resulting catalysts were used in the catalytic oxidation of cellobiose into gluconic acid. The interactions between the metals in the bimetallic catalysts were carefully investigated in order to unravel the effect of the second metal on the chemical and electronic properties of the active sites and their impact on the catalytic performance. Cu and Ruwere found to be promising promoters for the oxidation of cellobiose into gluconic acid, promoting oxygen activation in gold-catalyzed oxidation reactions, while Co and Pd were found to enhance the retro-aldol condensation of fructose into glycolic acid. In this case, the catalytic activity is dominated by the second metal added to Au. Hence, Au behaves more like a promoter of the second metal, preventing over oxidation and poisoning by the reaction intermediates and products. Ni specifically promoted the C-C scission, yielding a mixture of lower carbon-containing compounds and glycolic acid as the main products. The major reaction products obtained were gluconic acid, glycolic acid, ethylene glycol and erythritol. The catalytic activity of the catalysts followed the order: Au-Cu/TiO2 > Au-Pd/TiO2 > Au-Ru/TiO2 > Au-Co/TiO2 > Au/TiO2 > Au-Ni/TiO2. Upon comparison, Au-Ru/TiO2 was found to be an active and selective catalyst towards the formation of gluconic acid. The nature of the metal interactions in the bimetallic systems greatly influenced the product distribution.
    14 AIChE Annual Meeting; 11/2014
  • Yihu Dai, Ye Wang, Bin Liu, Yanhui Yang
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    ABSTRACT: Rapidly growing research interests surround heterogeneous nanocatalysis, in which metal nanoparticles (NPs) play a pivotal role as structure-sensitive active centers. With advances in nanotechnology, the morphology of metal NPs can be precisely controlled, which can provide well-defined models of nanocatalysts for understanding and optimizing the structure–reactivity correlations and the catalytic mechanisms. Benefiting from this, further credible evidence can be acquired on well-defined nanocatalysts rather than common multiphase systems, which is of great significance for the design and practical application of active metal nanocatalysts. Numerous studies demonstrate that enhanced structure-sensitive catalytic activity and selectivity are dependent not only on an increased surface-to-volume ratio and special surface atom arrangements, but also on tailored metal–metal and metal–organic–ligand interfaces, which is ascribed to the size, shape, composition, and ligand effects. Size–reactivity relationships and underlying size-dependent metal–oxide interactions are observed in many reactions. For bimetallic nanocatalysts, the composition and nanostructure play critical roles in regulating reactivities. Crystal facets favor individual catalytic selectivity and rates via distinct reaction pathways occurring on diverse atomic arrangements, both to low-index and high-index facets. High-index facets exhibit superior reactivities owing to their high-energy active sites, which facilitate rapid bond-breaking and new bond generation. Additionally, organic ligands may enhance the catalytic activity and selectivity of metal nanocatalysts via changing the adsorption energies of reactants and/or reaction energy barriers. Furthermore, atomically dispersed metals, especially single-atom metallic catalysts, have emerged recently, which can achieve better specific catalytic activity compared to conventional nanostructured metallic catalysts due to the low-coordination environment, stronger interaction with supports, and maximum service efficiency. Here, recent progress in shaped metallic nanocatalysts is examined and several parameters are discussed, as well as finally highlighting single-atom metallic catalysts and some perspectives on nanocatalysis. The integration of nanotechnology and nanocatalysis has been shaping up and, no doubt, the combination of sensitive characterization techniques and quantum calculations will play more important roles in such processes.
    Small 10/2014; · 7.51 Impact Factor
  • Source
    Chao He, Ke Wang, Yanhui Yang, Jing-Yuan Wang
    Energy & Fuels 09/2014; 28:6140-6150. · 2.73 Impact Factor
  • Applied Catalysis B Environmental 09/2014; s 156–157:385–397. · 6.01 Impact Factor
  • Kaixin Li, Linlu Bai, Yanhui Yang, Xinli Jia
    Catalysis Today 09/2014; 233:155-161. · 3.31 Impact Factor
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    Renewable and Sustainable Energy Reviews 08/2014; · 5.51 Impact Factor
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    ABSTRACT: Currently, levulinic acid (LA) and formic acid (FA) are considered as important carbohydrates for the production of value-added chemicals. Their direct production from biomass will open up a new opportunity for the transformation of biomass resource to valuable chemicals. In this study, one-pot transformation of cellobiose into LA and FA was demonstrated, using a series of multiple-functional ionic liquid-based polyoxometalate (IL-POM) hybrids as catalytic materials. These IL-POMs not only markedly promoted the production of valuable chemicals including LA, FA and monosaccharides with high selectivities, but also provided great convenience of the recovery and the reuse of the catalytic materials in an environmentally friendly manner. Cellobiose conversion of 100 %, LA selectivity of 46.3 %, and FA selectivity of 26.1 % were obtained at 423 K and 3 MPa for 3 h in presence of oxygen. A detailed catalytic mechanism for the one-pot transformation of cellobiose was also presented.
    ChemSusChem 08/2014; · 7.48 Impact Factor
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    ABSTRACT: In this report, three new metal-organic frameworks (MOFs), [Co3(μ3-OH)(HBTC)(BTC)2Co(HBTC)]·(HTEA)3·H2O (NTU-Z30), [Co(BTC)]·HTEA·H2O (NTU-Z31), [Co3(BTC)4]·(HTEA)4 (NTU-Z32), where H3BTC = 1,3,5-benzenetricarboxylic acid, TEA = triethylamine, and NTU = Nanyang Technological University, have been successfully synthesized under surfactant media and have been carefully characterized by single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis, and IR spectromtry. NTU-Z30 has an unusual trimeric [Co3(μ3-OH)(COO)7] secondary building unit (SBU), which is different from the well-known trimeric [Co3O(COO)6] SBU. The topology studies indicate that NTU-Z30 and NTU-Z32 possess two new topologies, 3,3,6,7-c net and 2,8-c net, respectively, while NTU-Z31 has a known topology rtl type (3,6-c net). Magnetic analyses show that all three materials have weak antiferromagnetic behavior. Furthermore, NTU-Z30 has been selected as the heterogeneous catalyst for the aerobic epoxidation of alkene, and our results show that this material exhibits excellent catalytic activity as well as good stability. Our success in growing new crystalline cobalt 1,3,5-benzenetricarboxylate MOFs under surfactant media could pave a new road to preparing new diverse crystalline inorganic materials through a surfactant-thermal method.
    Inorganic chemistry. 08/2014;
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    ABSTRACT: We demonstrate the coating of various 2D nanomaterials including MoS2 nanosheets, graphene oxide (GO) and reduced graphene oxide (rGO) with zeolitic imidazolate frameworks (i.e. ZIF-8) via a facile procedure. Additionally, ternary core-shell structures like Pt-MoS2@ZIF-8, Pt-GO@ZIF-8 and Pt-rGO@ZIF-8 have also been prepared. As a proof-of-concept application, memory device based on MoS2@ZIF-8 hybrid was fabricated and exhibited write-once-read-many-times (WORM) memory effect with high ON/OFF ratio and long operating lifetime. It is expected that MOF coated 2D nanomaterials may find wide applications in energy storage and conversion, catalysis, sensing and information storage devices.
    ACS Nano 07/2014; · 12.03 Impact Factor
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    ABSTRACT: The aerobic oxidation of 5-hydroxymethylfurfural (HMF), a key platform compound in cellulose transformation, into 2,5-furandicarboxylic acid (FDCA), a promising renewable alternative to petroleum-derived terephthalic acid, is one of the most attractive reactions for establishing biomass-based sustainable chemical processes. Supported Au catalysts have shown encouraging performance for this reaction, but the need of an excess amount of base additives makes the process less green and less cost-effective. Here, we report a stable and efficient carbon nanotube (CNT)-supported Au–Pd alloy catalyst for the aerobic oxidation of HMF to FDCA in water without any bases. The functionalization of CNT surfaces is crucial for FDCA formation. We have clarified that the CNT containing more carbonyl/quinone and less carboxyl groups favors FDCA formation by enhancing the adsorption of the reactant and reaction intermediates. Significant synergistic effects exist between Au and Pd in the alloy for the base-free oxidation of HMF to FDCA through three tandem steps. The present work provides understanding of the support-enhanced adsorption effect and the alloying effect for supported Au-based bimetallic catalysts, and this knowledge may help develop efficient catalysts for the aerobic oxidation of relatively complicated organic compounds with different functional groups in water.
    ACS Catalysis 06/2014; 4(7):2175–2185. · 7.57 Impact Factor
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    ABSTRACT: This paper describes the synthesis, characterization, and application of silica-supported Cu-Au bimetallic catalysts in selective hydrogenation of cinnamaldehyde (CALD). The results showed that Cu-Au/SiO2 bimetallic catalysts are superior to monometallic Cu/SiO2 and Au/SiO2 catalysts under identical conditions. Adding a small amount of gold (6Cu-1.4Au/SiO2 catalyst) afforded 8-fold higher catalytic reaction rate compared to Cu/SiO2 along with the high selectivity (53%, at 55% of conversion) towards cinnamyl alcohol (CALC). Characterization techniques such as X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), ultraviolet-visible spectroscopy (UV-Vis), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectra of chemisorbed CO, and X-ray photoelectron spectroscopy (XPS) were employed to understand the origin of the catalytic activity. A key genesis of the high activity of the Cu-Au/SiO2 catalyst was ascribed to the synergistic effect of Cu and Au species: the Au sites were responsible for the dissociative activation of H2 molecules, and Cu0 and Cu+ sites contributed to the adsorption-activation of C=C and C=O bond, respectively. A combined tuning of particle dispersion and its surface electronic structure was shown as a consequence of the formation of Au-Cu alloy nanoparticles, which led to the significantly enhanced synergy. A plausible reaction pathway was proposed based on our results and the literature. © 2014 American Institute of Chemical Engineers AIChE J, 2014
    AIChE Journal 06/2014; · 2.58 Impact Factor
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    ABSTRACT: Titania-supported gold nanoparticles were prepared by using the deposition–precipitation method, followed by reduction under a hydrogen flow. The catalytic activity of these as-prepared catalysts was explored in the oxidation of cellobiose to gluconic acid with molecular oxygen, and the properties of these catalysts were examined by using XRD, TEM, temperature-programmed desorption of NH3, energy-dispersive X-ray spectroscopy, UV/Vis, and X-ray photoemission spectroscopy (XPS). The catalyst sample reduced at high temperature demonstrated an excellent catalytic activity in the oxidation of cellobiose. The characterization results revealed the strong metal–support interaction between the gold nanoparticles and titania support. Hydrogen reduction at higher temperatures (usually >600 °C) plays a vital role in affording a unique interface between gold nanoparticles and titania support surfaces, which thus improves the catalytic activity of gold/titania by fine-tuning both the electronic and structural properties of the gold nanoparticles and titania support.
    ChemCatChem 05/2014; · 5.18 Impact Factor
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    ABSTRACT: The encapsulation of noble-metal nanoparticles (NPs) in metal-organic frameworks (MOFs) with carboxylic acid ligands, the most extensive branch of the MOF family, gives NP/MOF composites that exhibit excellent shape-selective catalytic performance in olefin hydrogenation, aqueous reaction in the reduction of 4-nitrophenol, and faster molecular diffusion in CO oxidation. The strategy of using functionalized cavities of MOFs as hosts for different metal NPs looks promising for the development of high-performance heterogeneous catalysts.
    Advanced Materials 04/2014; · 15.41 Impact Factor
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    ABSTRACT: A facile encapsulation strategy was reported for preparing nanoparticles/metal-organic framework hybrid thin films which exhibit both the active (catalytic, magnetic, and optical) properties derived from the NPs and the size-selectivity originating from the well-defined microporous structure of the MOF thin films.
    Chemical Communications 03/2014; · 6.38 Impact Factor
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    ABSTRACT: Oxidation catalysis not only plays a crucial role in the current chemical industry for the production of key intermediates such as alcohols, epoxides, aldehydes, ketones and organic acids, but also will contribute to the establishment of novel green and sustainable chemical processes. This review is devoted to dealing with selective oxidation reactions, which are important from the viewpoint of green and sustainable chemistry and still remain challenging. Actually, some well-known highly challenging chemical reactions involve selective oxidation reactions, such as the selective oxidation of methane by oxygen. On the other hand some important oxidation reactions, such as the aerobic oxidation of alcohols in the liquid phase and the preferential oxidation of carbon monoxide in hydrogen, have attracted much attention in recent years because of their high significance in green or energy chemistry. This article summarizes recent advances in the development of new catalytic materials or novel catalytic systems for these challenging oxidation reactions. A deep scientific understanding of the mechanisms, active species and active structures for these systems are also discussed. Furthermore, connections among these distinct catalytic oxidation systems are highlighted, to gain insight for the breakthrough in rational design of efficient catalytic systems for challenging oxidation reactions.
    Chemical Society Reviews 02/2014; · 30.43 Impact Factor
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    ABSTRACT: A new hexaprismane Co(ii)6(μ3-OH)6 cluster-based three-dimensional coordination polymer ({Co(μ3-OH)(HCOO)0.72(CH3COO)0.28}n, ) was successfully synthesized and characterized with single-crystal XRD, IR spectra, TGA spectra and elemental analysis. was used as an effective heterogeneous catalyst for the aerobic epoxidation of various alkenes. For the catalytic epoxidation of trans-stilbene, the conversion and selectivity towards the epoxide reached 98.6 and 98.0%, respectively. Also, an average TOF of 22 h(-1) was obtained for the reaction. The results indicated that displayed excellent aerobic epoxidation activity among the reported coordination polymer materials, even rivaling the traditional heterogeneous cobalt catalysts. The influence of the reaction parameters such as temperature and oxygen flow rate for the epoxidation of the trans-stilbene were also studied in detail.
    Dalton Transactions 12/2013; · 4.10 Impact Factor
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    ABSTRACT: Carbon nanotube supported Pt nano-catalyst was prepared by facile glow discharge plasma reduction operated at room temperature. The low-temperature plasma reduced Pt nanoparticles exhibited uniform size distribution and an average particle size of around 2.3 nm. Electrochemical measurements also proved that the plasma reduced Pt catalyst has remarkably higher active surface area comparing to the conventional hydrogen thermally reduced sample (3.6 nm in diameter). The plasma reduced Pt/CNT catalysts exhibited significantly higher conversion in benzyl alcohol aerobic oxidation compared to the hydrogen reduced Pt catalyst. Nonetheless, no obvious difference was found on the catalytic activity in terms of turn over frequency (TOF) between the plasma and hydrogen reduced Pt/CNT catalysts. Therefore, low temperature plasma reduction can effectively enhance Pt dispersion without changing its intrinsic catalytic property.
    Catalysis Today 08/2013; 211:104–108. · 3.31 Impact Factor
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    ABSTRACT: Metal oxides are of paramount importance in heterogeneous catalysis as either supports or active phases. Controlled synthesis of one-dimensional (1D) metal oxide nanostructures has received enormous attention in heterogeneous catalysis due to the possibility of tailoring the properties of metal oxides by tuning their shapes, sizes, and compositions. This feature article highlights recent advances in shape controlled synthesis of 1D metal oxide nanostructures and their applications in heterogeneous catalysis, with the aim of introducing new insights into the heterogeneous catalyst design.
    Nanoscale 07/2013; · 6.74 Impact Factor
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    ABSTRACT: Hybrids containing carbon nanotubes (CNTs) have attracted considerable attention in heterogeneous catalysis. In this study, a CNTs–Cu–SiO2 hybrid fabricated by urea-assisted gelation is disclosed to display excellent activity and outstanding long-term stability in the vapor-phase hydrogenation of dimethyl oxalate (DMO). Appropriate hybridization of CNTs with Cu–SiO2 results in enhanced Cu dispersion, which is suggested to be one of the key factors in determining the catalytic performance of copper catalysts. Furthermore, the growth of Cu nanoparticles (NPs) during the catalyst activation, DMO hydrogenation and severe aging tests is distinctively inhibited by incorporating CNTs into Cu–SiO2, leading to remarkably enhanced catalytic stability. The adsorption and activation of hydrogen on this particular hybrid catalyst are also influenced by the CNTs introduction.
    RSC Advances 06/2013; · 3.71 Impact Factor

Publication Stats

1k Citations
593.32 Total Impact Points

Institutions

  • 2014–2015
    • Xiamen University
      • Department of Chemistry
      Amoy, Fujian, China
  • 2007–2014
    • Nanyang Technological University
      • School of Chemical and Biomedical Engineering
      Tumasik, Singapore
  • 2010
    • Henan Normal University
      Henan’an, Guangdong, China
  • 2004–2007
    • Yale University
      New Haven, Connecticut, United States