Microkinetic modeling of cis-cyclooctene oxidation on heterogeneous Mn-tmtacn complexes

摘要

Experiments and microkinetic modeling were used to investigate the reaction mechanism of cis-cyclooctene oxidation with H _2O _2 on heterogeneous manganese 1,4,7-trimethyl-1,4,7-triazacyclononane (Mn-tmtacn) catalysts. A mechanism based on literature reports and model discrimination was identified that captured experimental data well, including data at reaction conditions that were not used for parameter estimation. H _2O _2 activation on the heterogeneous catalytic complex was identified as the rate-determining step (RDS), and a simple analytical rate expression was derived using the RDS and the pseudo-steady-state approximation for all intermediates. Predicted reaction orders for cis-cyclooctene, water, H _2O _2, catalyst, and diol and epoxide products are also consistent with experimental observations and can be rationalized according to the derived rate expression. In addition, the ratio of productive to unproductive H _2O _2 use is analyzed, and catalyst deactivation is found to be an important step in the reaction mechanism that is highly sensitive to temperature.