Yanhui Yang

Xiamen University, Amoy, Fujian, China

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Publications (142)721.27 Total impact

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    ChemPhysChem 05/2015; 16(7):1318-1318. DOI:10.1002/cphc.201590035 · 3.36 Impact Factor
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    ABSTRACT: In order to reduce considerable emissions of N-containing pollutants from combustion of sewage sludge derived solid fuel, an integrated system of hydrothermal deamination and air stripping was developed to effectively remove and recover nitrogen from dewatered sewage sludge (DSS). Three characteristic hydrothermal regimes contributing to deamination were identified. Initial hydrolysis of inorganic-N and labile protein-N was responsible for ammonium (NH+ 4-N) released below 300 oC/9.3 MPa, whereas deamination of pyridine-N dominated when being raised to 340 oC/15.5 MPa. At 380 oC and 22.0 MPa, remarkable deamination of stable protein-N occurred, which was accompanied by formation of more heterocyclic-N compounds and resulted in 76.9% N removal from DSS and 7980 mg/L NH+ 4-N solution. As a result of catalytic hydrolysis and cracking, calcium oxide additive not only accelerated deamination of stable protein-N, pyrrole-N, and pyridine-N but also favored transformations of protein-N and quaternary-N to nitrile-N and pyridine-N, respectively, leading to 86.4% total N removal efficiency. The nitrogen transformation reactions and conversion pathways during hydrothermal deamination were proposed and elaborated in detail. Moreover, an efficient air stripping process was coupled to remove and recover ammonia from liquid fraction via ammonium sulfate. Consequently, this system achieved an overall N recovery rate of 62%.
    Environmental Science & Technology 05/2015; 49(11):6872–6880. DOI:10.1021/acs.est.5b00652 · 5.48 Impact Factor
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    ABSTRACT: Carbon nanotubes are promising materials for various applications. In recent years, progress in manufacturing and functionalizing carbon nanotubes has been made to achieve the control of bulk and surface properties including the wettability, acid-base properties, adsorption, electric conductivity and capacitance. In order to gain the optimal benefit of carbon nanotubes, comprehensive understanding on manufacturing and functionalizing carbon nanotubes ought to be systematically developed. This review summarizes methodologies of manufacturing carbon nanotubes via arc discharge, laser ablation and chemical vapor deposition and functionalizing carbon nanotubes through surface oxidation and activation, doping of heteroatoms, halogenation, sulfonation, grafting, polymer coating, noncovalent functionalization and nanoparticle attachment. The characterization techniques detecting the bulk nature and surface properties as well as the effects of various functionalization approaches on modifying the surface properties for specific applications in catalysis including heterogeneous catalysis, photocatalysis, photoelectrocatalysis and electrocatalysis are highlighted.
    Chemical Society Reviews 04/2015; 44(10). DOI:10.1039/c4cs00492b · 30.43 Impact Factor
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    ABSTRACT: In the present study, hydrothermal conversion (HTC) of dewatered sewage sludge (DSS) under sub- and near-critical water has been performed to investigate effects of reaction temperature and pressure, moisture content of DSS, and calcium oxide (CaO) additive on evolution profile and characteristics of gas, solid, and liquid products. Although energy recovery rate decreased with increasing temperature and pressure, significant decarboxylation and dehydration reactions led to hydrochars with best fuel quality at 320 °C. High moisture content favored decarboxylation reaction but reduced H2 and CH4 yields. Compared to that in the absence of additive, H2 yield increased almost 6-fold at 380 °C and Ca/C molar ratio of 0.2, resulting in 58% H2 and 26% CH4 in final fuel gas. The results suggested that mineralization of heteroatomic compounds and dissolution of metals or mineral elements occurred during HTC. Under higher temperature and pressure, heavy metals or mineral elements were prone to be immobilized whereas dehalogenation became more distinct. CaO additive not only facilitated hydrolysis and deamination of organic compounds but also accelerated further fixation of inorganic elements and anions.
    International Journal of Hydrogen Energy 04/2015; 40(17):5776–5787. DOI:10.1016/j.ijhydene.2015.03.006 · 2.93 Impact Factor
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    ABSTRACT: Mesoporous-metal-organic frameworks (meso-MOFs) with size-, shape-, and space-distribution-controlled mesopores are obtained by a facile encapsulation and selective etching strategy of metal nanoparticles. Hierarchical or functionalized meso-MOFs are achieved by the above strategy. Interestingly, the functional meso-MOFs display higher catalytic activity originating from the mesopores existing in the MOFs, as well as good selectivity due to protection of the micro-porous frameworks. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Advanced Materials 03/2015; 27(18). DOI:10.1002/adma.201405752 · 15.41 Impact Factor
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    ABSTRACT: The catalytic activity of gold supported on ZSM5 (Au/ZSM5) was investigated for the selective oxidation of ethanol in the presence of excess oxygen. Au/ZSM5 catalyst pretreated by nonthermal O2 plasma method showed the best oxidative activity compared to low-temperature calcination in air and high-temperature reduction in hydrogen atmosphere. Results from microscopy and X-ray diffraction characterizations proved that plasma pretreatment afforded a small Au particle size and a uniform dispersion of Au nanoparticles on ZSM5 surfaces. Characterization results further demonstrated that the residual ammonia adsorbed on ZSM5 surfaces during the precipitation can be oxidized to nitrate ions by nonthermal O2 plasma treatment, while it converted to NO+ by low-temperature oxygen calcination and was completely removed by high-temperature hydrogen reduction. Dissimilar surface/interface properties caused the tremendously different interaction between gold nanoparticles and zeolite support, and consequently the catalytic performances in ethanol oxidation. In particular, under the nonthermal O2 plasma pretreatment, the formed NO3− species lowered the acidity of ZSM5 surfaces as well as anchored the Au nanoparticles, resulting in nearly 100% selectivity toward selective oxidation instead of acid-catalyzed reactions even under high reaction temperature.
    Catalysis Today 02/2015; DOI:10.1016/j.cattod.2015.01.020 · 3.31 Impact Factor
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    ABSTRACT: Ternary core–shell heterostructured rutile@anatase@Crx Oy nanorod arrays were elaborately designed as photoanodes for efficient photoelectrochemical water splitting under visible‐light illumination. The four‐fold enhanced and stabilized visible‐light photocurrent highlights the unique role of the interim anatase layer in accelerating the interfacial charge transfer from the Crx Oy chromophore to rutile nanorods. Driving light: Ternary core–shell heterostructured rutile@anatase@Crx Oy nanorod arrays are elaborately designed as photoanodes for photoelectrochemical water splitting under visible‐light irradiation. Thus, affording a novel strategy to extend the photoresponse of oxide array materials, and showing the promising application of rutile@anatase@Crx Oy photoanodes in the domain of photoelectrochemistry.
    ChemPhysChem 02/2015; 16(7). DOI:10.1002/cphc.201402905 · 3.36 Impact Factor
  • Linlu Bai, Lin Yao, Yanhui Yang, Jong-Min Lee
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    ABSTRACT: A novel microspherical composite with an Au@SiO2 core and mesoporous aluminosilica shell is synthesized and used as the heterogeneous catalyst in the aerobic epoxidation of cis-cyclooctene, exhibiting great catalytic activity and stability.
    Chemical Communications 02/2015; DOI:10.1039/c4cc09570g · 6.72 Impact Factor
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    Applied Catalysis B Environmental 01/2015; 162:401–411. DOI:10.1016/j.apcatb.2014.07.012 · 6.01 Impact Factor
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    ABSTRACT: We report here the composition optimization of ZnxFe3-xO4 hollow nanospheres for enhancing microwave attenuation. ZnxFe3-xO4 hollow nanospheres were synthesized through a simple solvothermal process. The maximum magnetization moment of 91.9 emu/g can be obtained at x=0.6. The composite filled with Zn0.6Fe2.4O4 exhibited the bandwidth of 3.21~8.33 GHz for RL< -10 dB and a maximum relative bandwidth (Wp,max) of 88.6% at optimized thickness t0=0.34 cm. The enhancement should be attributed to the enhanced permeability resonance at high frequency. This optimized hollow material is very promising to be used as a mass efficient and broadband microwave attenuation material.
    ACS Applied Materials & Interfaces 12/2014; 6(24). DOI:10.1021/am5075612 · 5.90 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; 11(3). DOI:10.1002/smll.201400847 · 7.51 Impact Factor
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    Chao He, Ke Wang, Yanhui Yang, Jing-Yuan Wang
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    ABSTRACT: In the absence of prior drying, dewatered sewage sludge (DSS) was directly converted to hydrochars with superior fuel characteristics in subcritical water. Hydrochar derived at 320 degrees C and 12.0 MPa (SHC-320) was screened for systematic cocombustion with different-rank coals. The results suggest that SHC-320 reduced the activation energy of the blends and altered the main combustion profiles. Meanwhile, blending of SHC-320 induced greater heat loss for higher-rank coals, whereas a higher portion of SHC-320 further improved the ignition reactivity of high-rank coal blends. In the high-temperature region, the value of the pre-exponential factor increased with increasing coal/SHC-320 ratio, resulting in more intense synergistic effects in blends. At a low coal/SHC-320 ratio (30:70), intense antisynergistic effects occurred in cocombustion with low- or high-rank coals. As a result of distinct synergistic interactions, cocombustion with moderate-rank coal achieved the best combustion efficiency among the blends. These findings benefit efficient utilization of DSS as a hydrochar solid fuel in existing cofiring power plants.
    Energy & Fuels 09/2014; 28:6140-6150. DOI:10.1021/ef501386g · 2.73 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 09/2014; 60(9). DOI:10.1002/aic.14522 · 2.58 Impact Factor
  • Kaixin Li, Linlu Bai, Yanhui Yang, Xinli Jia
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    ABSTRACT: The kinetics of ionic liquid-heteropolyanion (IL-HPA) salts catalyzed transesterification of oleic acid methyl ester (OAME) was studied via a sequential method. The method can be separated into two parts. The first part was to analyze the kinetics of transesterification of OAME catalyzed by a novel catalyst and to provide a way to simulate the reaction rate profile. The second part was to verify the appropriateness of kinetic parameters calculated in the first part. Kinetic parameters were properly determined and reaction rate profiles were adequately simulated by regarding transesterification as a second order reaction. A good agreement between the experimental data and theoretically predicted values is obtained. This method may be applicable to most of three-step consecutive reaction whose t(max,first intermediate) and t(max,second intermediate) at the maximum concentration are acquirable, representatively and reliably.
    Catalysis Today 09/2014; 233:155-161. DOI:10.1016/j.cattod.2013.12.035 · 3.31 Impact Factor
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    ABSTRACT: Palladium nanoparticles supported on carbon nanotubes (CNT) functionalized with various organosilane modifiers have been prepared through a post-synthesis grafting method followed by a metal adsorption-reduction approach. The surface property, catalyst structure, electrochemical activity, and catalytic performance were tested in the selective aerobic oxidation of benzyl alcohol. The variation in type and amount of surface-functional groups played a key role in controlling catalytic behavior through fine tuning the surface basicity, metal nanoparticle size and size distribution, metal-support electronic interaction. In all these tested organosilane modifiers, 3-aminopropyl triethoxysilane exhibited the largest improvement in catalytic performance, with a remarkably high quasi-turnover frequency of 288,755 h(-1) based on the electrochemical active surface area.
    Applied Catalysis B Environmental 09/2014; s 156–157:385–397. DOI:10.1016/j.apcatb.2014.03.043 · 6.01 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 09/2014; 7(9). DOI:10.1002/cssc.201402157 · 7.12 Impact Factor
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    ABSTRACT: Sewage sludge is bio-solid with high moisture content generated from wastewater treatment plants. Due to the avoidance of energy-intensive dewatering, hydrothermal conversion of sewage sludge becomes a promising technology to simultaneously achieve energy recovery and solid waste management. In order to obtain an entire understanding of applicability of hydrothermal gasification for hydrogen rich gas production from sewage sludge, this review article discussed hydrothermal conversion and gasification processes in terms of fundamental principles, operating conditions, partial oxidative gasification, and detrimental effects of intermediates. Furthermore, since organic compounds in sewage sludge are mainly composed of carbohydrates, proteins, lipids, and lignin, this article comprehensively reviewed hydrogen production from these biomass model compounds and their hydrolysis products under sub- and supercritical water. Additionally, introduction of alkali salts and heterogeneous catalysts to enhance hydrogen yield under mild temperatures and pressures in hydrothermal gasification process was also discussed. Based on bench and pilot scale studies, supercritical water gasification of sewage sludge for hydrogen production is feasible in terms of technical and economic evaluation. Given issues concerning corrosion, plugging and high operating cost, a combined supercritical water gasification and catalytic hydrothermal gasification concept is proposed as a practical strategy to directly harness hydrogen from sewage sludge in future applications.
    Renewable and Sustainable Energy Reviews 08/2014; 39:1127–1142. DOI:10.1016/j.rser.2014.07.141 · 5.51 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; 53(16). DOI:10.1021/ic5011133 · 4.79 Impact Factor
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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; 8(8). DOI:10.1021/nn503834u · 12.03 Impact Factor

Publication Stats

3k Citations
721.27 Total Impact Points

Institutions

  • 2014–2015
    • Xiamen University
      • • Department of Chemistry
      • • College of Chemistry and Chemical Engineering
      Amoy, Fujian, China
  • 2006–2015
    • Nanyang Technological University
      • School of Chemical and Biomedical Engineering
      Tumasik, Singapore
  • 2004–2007
    • Yale University
      • • Department of Biomedical Engineering
      • • Department of Chemical & Environmental Engineering
      New Haven, Connecticut, United States