| Popis: |
A study has been made of the kinetics and mechanism of the oxidation of styrene over a heterogeneous vanadate-monolayer Li2PdCl4 Wacker catalyst in the temperature range 348 K to 453 K at 0.11 MPa total pressure. The kinetics of the reaction, with respect to the dependence of the reaction rate on the partial pressures of styrene and water, as well as on the surface LiCl concentration, appear to be logically related to the kinetics of the homogeneous Wacker process. In addition to acetophenone (initial selectivity 45 mol %), benzaldehyde, probably originating from phenylacetaldehyde, is formed with gradually increasing selectivity (initial selectivity 55 mol %). Formation of benzoic acid can sometimes be detected but in all cases with a selectivity lower than 5 mol %. Initially no other products are detected but, after a short period, trans-cinnamaldehyde is formed with increasing selectivity (15 mol % after three days). Deactivation of the catalyst is due to carbonaceous deposits and removal of these deposits by oxidation with air at 473 K leads to partial regeneration. |
