Among all the possible routes of preparing OPP, the condensation and dehydrogenation process from cyclohexanone has the most extensive applied prospect.

This macromolecular metalloporphyrin was used as the catalyst for the first time for cyclohexane oxidation to cyclohexanol and cyclohexanone with air in the absence of additives or solvents.

HPO process which is composed of cyclohexanone preparation, hydroxylamine oximation and cyclohexanone-oxime rearrangement has been applied widely in Caprolactam Industry.