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Dmitry Yu. Murzin - One of the best experts on this subject based on the ideXlab platform.

  • Heterogeneous Catalytic Kinetics
    Catalytic Kinetics, 2016
    Co-Authors: Dmitry Yu. Murzin, Tapio Salmi
    Abstract:

    Basic Kinetics schemes for heterogeneous Catalytic reactions such as Eley-Rideal, Langmuir-Hinshelwood, and two-step sequence are considered. Examples of rate derivation for complex reactions with one route are presented. Kinetic models are presented for reactions on real surfaces with intrinsic or induced nonuniformity. Kinetics of single-route Christiansen sequences as well as consecutive and parallel reactions is discussed. Approaches are given for accounting of the multicentered nature of adsorbed compounds in kinetic modeling. Kinetic models where the solvent effects are incorporated in the rate equations beyond considerations of gas solubility and solvent adsorption are advanced. Kinetics of transfer of labeled atoms in heterogeneous Catalytic reactions is illustrated with several examples. ElectroCatalytic and photoCatalytic Kinetics is considered as special cases of heterogeneous Catalytic Kinetics. Cluster-size-dependent Kinetics is quantitatively treated.

  • Homogeneous Catalytic Kinetics
    Catalytic Kinetics, 2016
    Co-Authors: Dmitry Yu. Murzin, Tapio Salmi
    Abstract:

    Kinetics of homogeneous reactions is presented for acid-base and organocatalysis, catalysis by metal ions and transition metals, as well as polymerization reactions. Linear reaction mechanisms with different number of steps are considered. Catalyst systems with ligand-deficient catalysts are described. Kinetic expressions are presented for mechanisms with several reaction routes.

  • On Cluster Size Dependent Activity and Selectivity in Heterogeneous Catalysis
    Catalysis Letters, 2012
    Co-Authors: Dmitry Yu. Murzin
    Abstract:

    The impact of nanoparticle size effects in heterogeneous Catalytic Kinetics over supported metal catalysts is discussed for clusters having several distinct active sites. Theoretical analysis demonstrates that considerations of different activity for such sites not only allow a description of a smooth increase or decrease of turnover frequency as a function of cluster size, but also can in principle account for maxima in turnover frequency. Several examples are presented addressing advantages and shortcomings of the model (in some cases giving physically unreasonable values of parameters during numerical data fitting). Comparison with a rival model with a continuous variation of activity is presented. Graphical Abstract

  • Influence of Cluster Size Distribution on Cluster Size Dependent Catalytic Kinetics
    Catalysis Letters, 2011
    Co-Authors: Dmitry Yu. Murzin, I. L. Simakova
    Abstract:

    A theoretical analysis of the influence of particle size distribution on observed TOF dependence on cluster size is presented for a two step Catalytic cycle. Such mechanism can display different TOF behavior including maxima. In the later case simulations demonstrated broadening of TOF curves compared to an idealized case of very narrow PSD. However, for more often observed cases with smooth TOF increase or decrease with cluster size increase incorporation of particle size distribution in kinetic analysis is not required at least for often experimentally observed particle size distributions. Graphical Abstract

  • NanoKinetics for nanocatalysis
    Catalysis Science & Technology, 2011
    Co-Authors: Dmitry Yu. Murzin
    Abstract:

    The impact of nanoscience on heterogeneous catalysis is discussed with an emphasis on Catalytic Kinetics. Examples are presented demonstrating that the size of nanoparticles as well as the size of reacting molecules, which should be accounted for in the explanation of activity and selectivity.

Tao Chen - One of the best experts on this subject based on the ideXlab platform.

  • Revealing the thermodynamics of individual Catalytic steps based on temperature-dependent single-particle nanocatalysis.
    Physical chemistry chemical physics : PCCP, 2019
    Co-Authors: Xiaodong Liu, Tao Chen
    Abstract:

    Due to the intrinsic heterogeneity of nanocatalysis, many underlying Catalytic details on nanocatalysts are hidden in ensemble-averaged measurements. Here, the single-molecule approach was adopted to study the temperature-dependent Catalytic Kinetics and dynamics of individual Pt nanoparticles and then reveal the thermodynamics of individual Catalytic steps on Pt nanoparticles. In this way, the temperature-dependent Catalytic Kinetics (the effective rate constant of the product formation process, the rate constants of the direct/indirect production desorption process and the substrate adsorption equilibrium constants) and thermodynamics (free energy, entropy and enthalpy of substrate adsorption) were obtained systematically at the single particle level. Based on such results, we further obtained the activation energies of the Catalytic product formation step and the direct/indirect product desorption steps. Moreover, by analyzing the temperature-dependent surface restructuring rates of individual Pt nanocatalysts, the activation energies of both the catalysis-induced surface restructuring and the spontaneous surface restructuring were obtained for the first time. All these results obtained here deepen our understanding of the Catalytic thermodynamics of nanocatalysts.

  • Size-dependent Catalytic Kinetics and dynamics of Pd nanocubes: a single-particle study
    Physical chemistry chemical physics : PCCP, 2016
    Co-Authors: Tao Chen, Yuwei Zhang
    Abstract:

    Due to the well-known significant effect of the size on the Catalytic activity of nanocatalysts, here we use single-molecule fluorescence microscopy to study the size-dependent Catalytic Kinetics and dynamics of individual Pd nanocubes. A series of size-dependent Catalytic properties were revealed in both product formation and product desorption processes. It was found that, due to the different adsorption mechanisms of substrate molecules on Pd nanocubes, H2 adsorption is independent of the size of Pd nanocubes, while the large flat resazurin molecules show stronger adsorption on larger sized Pd nanocubes. Apparently, the Pd nanocubes can be divided into three types: when the size of the Pd nanocube is small, substrate binding can prohibit product desorption and product desorption prefers the direct pathway; when the size is in an appropriate range, the product desorption process could be independent of substrate binding and shows no selectivity between two parallel desorption pathways; if the size is large enough, substrate binding can promote product desorption and product desorption prefers the indirect pathway. We also observed the surface-restructuring-induced dynamic heterogeneity of individual Pd nanocubes in both product formation and desorption processes with timescales of about tens to one hundred seconds. The activity fluctuation of individual Pd nanocubes was found to be mainly due to the spontaneous surface-restructuring rather than the catalysis. Furthermore, we estimated the size-dependent activation energies and time scales of spontaneous dynamic surface restructuring, which are fundamental to heterogeneous catalysis. The work presented here reveals new insight into nanocatalysis and exemplifies the advantages of the single-molecule approach in probing the Catalytic properties of nanocatalysts.

  • Catalytic Kinetics of different types of surface atoms on shaped pd nanocrystals
    Angewandte Chemie, 2016
    Co-Authors: Tao Chen, Sheng Chen, Yuwei Zhang, Yifeng Qi, Yuzhou Zhao, Weilin Xu, Jie Zeng
    Abstract:

    To understand the Catalytic properties or roles of different types of surface atoms on metal nanocatalysts, the Catalytic Kinetics and dynamics of the different types of surface atoms (plane and edge) were revealed for the first time by a statistical quantitative deconvolution of observables obtained from traditional single-molecule nanocatalysis of Pd nanocrystals.It was found that the edge and plane of Pd nanocubes show similar size-dependent product formation processes, but inverse product dissociation processes. This work helps push the traditional single-molecule nanocatalysis method towards the sub-particle level.

Zhong-liang Zhu - One of the best experts on this subject based on the ideXlab platform.

  • Simplified data processing for the simultaneous determination of catalysts by Catalytic Kinetics.
    Talanta, 1993
    Co-Authors: Zhong-liang Zhu, Xian-de Wang
    Abstract:

    An approximate equation for data processing is proposed for the simultaneous determination of catalysts by Catalytic Kinetics. On applying the equation to the reaction between two reactants catalysed by two catalysts, the calculation is simplified to that of only one reactant, simplifying the experiment and data processing. The equation was used to treat the simultaneous determination of ruthenium and osmium with Ce(IV)As(III) as the indicator reaction, with the results in good agreement with those using the exact equation.

  • Simultaneous determination of iodide and nitrite by Catalytic Kinetics
    The Analyst, 1993
    Co-Authors: Zhong-liang Zhu
    Abstract:

    Nitrite and iodide can be determined simultaneously by a single experiment using their kinetic effect on the colour fading of the iron(II)–thiocyanate complex in nitric acid solution. The rate of the colour-fading reaction is in proportion to the concentration of iodide and is independent of the concentration of nitrite. The length of the induction period of the indicator reaction is in inverse proportion to the logarithm of the concentration of nitrite and is independent of the concentration of iodide. Under conditions of 1.3 mol l–1 HNO3, 0.067 mol l–1 Fe3+ and 2.7 × 10–4 mol l–1 SCN–, concentrations of 4.0 × 10–5–1.6 × 10–4 mol l–1 iodide and 4.1 × 10–7–6.6 × 10–6 mol l–1 NO2– were determined with mean relative errors of 1.5 and 3.9%, repectively.

Yuwei Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Size-dependent Catalytic Kinetics and dynamics of Pd nanocubes: a single-particle study
    Physical chemistry chemical physics : PCCP, 2016
    Co-Authors: Tao Chen, Yuwei Zhang
    Abstract:

    Due to the well-known significant effect of the size on the Catalytic activity of nanocatalysts, here we use single-molecule fluorescence microscopy to study the size-dependent Catalytic Kinetics and dynamics of individual Pd nanocubes. A series of size-dependent Catalytic properties were revealed in both product formation and product desorption processes. It was found that, due to the different adsorption mechanisms of substrate molecules on Pd nanocubes, H2 adsorption is independent of the size of Pd nanocubes, while the large flat resazurin molecules show stronger adsorption on larger sized Pd nanocubes. Apparently, the Pd nanocubes can be divided into three types: when the size of the Pd nanocube is small, substrate binding can prohibit product desorption and product desorption prefers the direct pathway; when the size is in an appropriate range, the product desorption process could be independent of substrate binding and shows no selectivity between two parallel desorption pathways; if the size is large enough, substrate binding can promote product desorption and product desorption prefers the indirect pathway. We also observed the surface-restructuring-induced dynamic heterogeneity of individual Pd nanocubes in both product formation and desorption processes with timescales of about tens to one hundred seconds. The activity fluctuation of individual Pd nanocubes was found to be mainly due to the spontaneous surface-restructuring rather than the catalysis. Furthermore, we estimated the size-dependent activation energies and time scales of spontaneous dynamic surface restructuring, which are fundamental to heterogeneous catalysis. The work presented here reveals new insight into nanocatalysis and exemplifies the advantages of the single-molecule approach in probing the Catalytic properties of nanocatalysts.

  • Catalytic Kinetics of different types of surface atoms on shaped pd nanocrystals
    Angewandte Chemie, 2016
    Co-Authors: Tao Chen, Sheng Chen, Yuwei Zhang, Yifeng Qi, Yuzhou Zhao, Weilin Xu, Jie Zeng
    Abstract:

    To understand the Catalytic properties or roles of different types of surface atoms on metal nanocatalysts, the Catalytic Kinetics and dynamics of the different types of surface atoms (plane and edge) were revealed for the first time by a statistical quantitative deconvolution of observables obtained from traditional single-molecule nanocatalysis of Pd nanocrystals.It was found that the edge and plane of Pd nanocubes show similar size-dependent product formation processes, but inverse product dissociation processes. This work helps push the traditional single-molecule nanocatalysis method towards the sub-particle level.

Hung‐ju Lin - One of the best experts on this subject based on the ideXlab platform.

  • Catalytic Kinetics of quaternary ammonium poly(styrene-co-methylstyrene) resin
    AIChE Journal, 2006
    Co-Authors: Hung‐ju Lin
    Abstract:

    The Catalytic Kinetics and synthesis of poly(styrene-co-chloromethylstyrene) resin of different degrees of crosslinkages and ring substitutions were investigated by copolymerizing styrene and chloromethylstyrene through crosslinking with divinylbenzene. Poly-(styrene-co-chloromethylstyrene) quaternary ammonium salt was obtained with activating poly(styrene-co-chloromethylstyrene) resin with tertiary amine. More than 20 types of poly(styrene-co-chloromethylstyrene) quaternary ammonium catalyst were prepared, with reaction conditions including immobilized time (0.J25∼4 days), concentration of tertiary amine (0. J∼2 kmol/m 3 ), kinds of solvents in immobilization (methanol, ethyl alcohol, and DMF), and kinds of tertiary amines (trimethylamine, triethylamine, tripropylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, and tri-n-octylamine). These catalysts were used to achieve the optimum allylation of phenol. The reactions were conducted and studied individually with either equal mole or equal weight of catalyst. The best reactivity for the allylation of phenol was obtained when the structure of the quaternary ammonium catalyst was 10% degree of ring substitution and 2% degree of crosslinkage activating with trihexylamine. The turnover number and the effectiveness factor were also calculated.