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A novel approach in kinetic study of CO hydrogenation reaction over Co-Ni/AlO catalyst was described. The experimental data were collected using a fixed bed micro reactor under next conditions: pressure 2-12 bar, temperature 230-280°C, molar ratio H: CO = 1-3, space velocity 2000-2700 h. A new Langmiur-Hinshelwood (LH) kinetic model on the basis of formyl mechanism was developed. The apparent activation energy of LH kinetic model, bond energy of carbon, oxygen, hydrogen and some surface intermediate on catalyst surface, activation energies of some surface reactions and catalyst surface coverage were estimated from a new combined LHHW/UPI-QEP methodology. It was postulated that under reaction conditions used, CH formation through H-assisted CO dissociation is probably dominant mechanism of hydro-genation over Co-Ni catalyst. [ABSTRACT FROM AUTHOR]

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 CH 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 carbon from CO dissociation, but the synthesis of hydrocarbons and oxygenates can effectively proceed on Cu(111) surface. For optimum performance of F-T synthesis catalyst, these conflicting properties must be optimized. In this regard, we studied Fe/Cu alloy catalyst. On all the catalyst surfaces, the energetically preferred path to initiate the alkyl chain growth is via insertion of a CH group into the carbon-metal bond of a CH group. On FeCu catalyst surface, the activation barrier for termination of alkyl chain growth by β-elimination of hydrogen is found to be lower than that for α-addition of hydrogen and consequently for this catalyst, olefins are expected to form more readily than paraffins. The results of the model for a single metal surface are in agreement with the experimental data. [ABSTRACT FROM AUTHOR]