Book Description

Cyclohexane oxidation is an industrially important reaction used as the first step in production of Nylon 6 and Nylon 6,6. Commercial technology employs a two stage process. The first stage of cyclohexane oxidation is very inefficient with 4-8% conversion of cyclohexane with 80% selectivity to cyclohexanol and cyclohexanone as desired products. According to some previously published work, using pure oxygen as an oxidant instead of conventionally used air, decreases the time needed to achieve 4% cyclohexane conversion; thus, increasing volumetric productivity at reported increased selectivity. The focus of this work was to systematically examine the effect of increased availability of oxygen on the rates and the selectivity of cyclohexane oxidation. It was concluded from the experimental and the modeling results that increased oxygen availability improves the productivity of cyclohexane oxidation at the fixed cyclohexane conversion (4%) as the residence time required achieving such conversion declines with the increase in oxygen concentration. A novel capillary reactor has been designed and tested for cyclohexane oxidation as a safer and more efficient way for hydrocarbon oxidation with oxygen or oxygen enriched air. The discrepancy between the experimental and modeling results was attributed to lower than expected gas-liquid mass transfer in the capillary Thus, it was concluded that the gas liquid reactions of this nature can be performed in the small diameter capillary reactor but the gas-liquid mixing has to be resolved in a better fashion and mass transfer improved.