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    Thermokinetic study of Fischer-Tropsch synthesis on Fe2Cu 1 and FeCu surfaces with comparison to Fe(110) and Cu(111) catalysts by the UBI-QEP method

    , Article Journal of the Iranian Chemical Society ; Vol. 11, issue. 5 , 2014 , pp. 1305-1310 ; SSN: 1735-207X Javadi, N ; Sajjadifar, S ; Sharif University of Technology
    The purpose of this study is to predict the activation barriers and enthalpy for elementary steps in the process of Fischer-Tropsch (F-T) on the surfaces of Fe(110), Cu(111) and Fe/Cu alloys catalyst using "Unity Bond Index-Quadratic Exponential Potential" method aimed at predicting the activity and selectivity on the basis of energy criteria. The elementary steps, such as dissociation of CO, hydrogenation of carbidic carbon, C-C chain growth by insertion of CH2 versus CO into the metal-alkyl bonds, and chain termination, which lead to hydrocarbons (alkanes versus α-olefins) or oxygenates are discussed in detail. The results show that metallic Fe(110) is necessary to produce the carbidic... 

    On the energetics of NH3 adsorption and decomposition on Nb(100) surface: A UBI-QEP study

    , Article Reaction Kinetics and Catalysis Letters ; Volume 76, Issue 1 , 2002 , Pages 43-51 ; 01331736 (ISSN) Azizian, S ; Gobal, F ; Sharif University of Technology
    The energetics of the adsorption and decomposition of ammonia on Nb(100) surface was investigated by the method of unity bond index-quadratic exponential potential (UBI-QEP). The experimental as well as theoretically derived atomic heats of adsorption were used as the input data and the results were compared with the findings of local density functional theory (LDFT) and non-local density functional theory (NLDFT). The method was capable of correctly predicting the fragmentation of ammonia on 4-fold hollow sites on the surface of Nb(100) and magnitudes of the heats of adsorption and activation energies were more realistic  

    Investigation of the energetics of the decomposition of azomethane on Pd(111): The UBI-QEP approach

    , Article Surface Review and Letters ; Volume 10, Issue 6 , 2003 , Pages 895-901 ; 0218625X (ISSN) Azizian, S ; Gobal, F ; Sharif University of Technology
    The method of unity bond index-quadratic exponential potential (UBI-QEP) is employed to derive the energetic parameters associated with the steps of the pathway which we propose for the catalytic decomposition of azomethane on the Pd(111) surface. According to the energy calculations, azomethane adsorbs molecularly in trans-configuration and then decomposes to CH3N with no activation energy. The reaction continues by tilting and dehydrogenation to the products (H2 and HCN). The calculated activation energies at various surface coverages perfectly account for the variation of relative yields of H2 and HCN with changing of the coverage of azomethane. According to the calculations, desorption...