A multistep methodology for the quantitati®e determination of rate constants of a detailed surface-reaction mechanism is proposed. As a starting point, thermodynamically consistent, co®erage-dependent acti®ation energies and heats of reactions were de-ri®ed from the application of the unity bond index ᎐ quadratic exponential potential formulation, and initial estimates of the preexpontentials were obtained from transition-state theory or a®ailable experiments. Important feature identification analysis was performed to determine key kinetic parameters for ®arious experiments. Model responses were parameterized in terms of these important parameters by polynomials and factorial design techniques, and these parameterized responses were subsequently used in simultaneous optimization through simulated annealing against different sets of experimental data to obtain a quantitati®e reaction mechanism that is ®alid o®er a wide range of operating conditions. The technique was successfully applied to the de®elopment of a comprehensi®e reaction mechanism for H rair mixtures on polycrystalline Pt.

A new methodology is presented for calculating parameters of complex surface reaction mechanisms. This approach takes into consideration adsorbate−adsorbate interactions along with their influence on the activation energies of surface reactions as a function of operating conditions. It combines an extension of the unity bond index−quadratic exponential potential theory, reactor scale modeling, important feature identification, and model validation. The H2 oxidation over platinum has been chosen as a model system to test this methodology. Comparison with a variety of available experimental data in the literature, such as catalytic ignition temperature, laser-induced fluorescence OH desorption measurements, catalytic autotherms, and species profiles, shows that the proposed surface mechanism is capable of quantitatively capturing all the important features of the published experiments. Our approach offers the potential of quantitative modeling of catalytic reactors exhibiting complex surface reaction processes under realistic operating conditions.

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The dimerization of isobutene (IB) followed by hydrogenation is looked upon as an important route to produce the octane booster isooctane (IO), because of doubts being raised about methyl tert-butyl ether (MTBE) being a clean fuel additive because of its substantial solubility in water. In the present work, the dimerization of IB has been carried out in a batch reactor over a temperature range of 65-95 °C in the presence of ion-exchange resin as a catalyst and isooctane as a solvent. The influence of various parameters such as temperature, catalyst loading, concentration of water, and initial concentration of IB was examined. Because several side reactions are involved in this reacting system, the selectivity of IB toward the dimers is an important issue. The presence of a polar compound in the reaction mixture plays a vital role as an inhibitor to the side reactions and improves the selectivity toward the dimers. In the present system, water was used as an inhibitor, which leads to the formation of tert-butyl alcohol (TBA) through the hydration of IB. A rigorous kinetic model is proposed to explain the experimental data. All of the reactions such as the reversible dehydration of TBA, dimerization, trimerization, and oligomerization of IB are considered explicitly in the kinetic models. The developed kinetic models would be versatile enough to design a commercial reactor such as a fixed-bed reactor or a reactive distillation column.

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