Capillary reactor for cyclohexane oxidation with oxygen

Cyclohexane oxidation is the first step in the currently used technology for production of Nylon-6 and Nylon-6,6 which employs a two-stage process. In the first stage 80% selectivity to two main products, cyclohexanol and cyclohexanone (KA oil) is obtained at 4–8% cyclohexane conversion in staged bubble columns or stirred tanks. There have been reports that increased oxygen concentration in the gas phase or pure oxygen is beneficial to cyclohexane oxidation and this was confirmed in our previous study (Jevtic et al., 2009). To fully utilize this advantage here, we present a novel, safer capillary reactor for cyclohexane oxidation with pure oxygen. The discrepancy between the experimental and modeling results was attributed to lower than expected mass transfer achieved in the capillary. With a better design for gas–liquid mixing and contacting this type of a reactor could potentially become attractive for gas–liquid reactions of similar nature.