One-step catalytic synthesis of ε-caprolactam from cyclohexane nitrosation catalyzed by transition VPO composites

A series of transition metal-doped M1-M2 vanadium phosphorus oxide(VPO)(M1=Mn,M2=Al,Mg,Ti)composite catalysts were prepared by the reduction-dipping method,and were employed to catalyze reaction of cyclohexane with nitrosyl sulfuric acid in the presence of fuming sulfuric acid.e-caprolactam was directly obtained from such one-step catalytic process.Among them,the Mn-Al-VPO gave the best results with 17.1% of conversion and 75.6% of selectivity to e-caprolactam.A possible mechanism is proposed.