Study On Acrolein Oxidation And Baeyer-Villiger Oxidation Of Cyclohexanone Catalyzed By Nitrogen-doped Carbon Nanotubes

Acroleic acid(AA)is an important industrial raw material,from which the derivative polymers can be applied to many aspects of chemical industry.So far,AA is commonly produced by a two-step oxidation of propylene as a raw material.In the second step,AA is produced via the oxidation of acrolein(ACR)on Mo/V/W metal oxide catalysts.In general,the reaction temperature is above 220 oC,and the selectivity of AA is about 80%.The harsh reaction conditions increase the energy consumption and environmental burden.Therefore,the study on developing appropriate catalysts and exploring mild reaction conditions is of great scientific and industrial significance.As a metal-free catalyst,nitrogen-doped carbon nanotubes(NCNTs)show an excellent catalytic performance in liquid-phase oxidation reactions.In this work,we focus on the ACR oxidation and cyclohexanone-ACR co-oxidation in the liquid-phase.The catalytic performance of NCNTs on ACR to AA was systematically investigated.It was found that the participation of cyclohexanone could increase the yield of AA.The main contents are as follows.(1)For the first time,AA is produced via the liquid-phase oxidation of ACR on NCNTs.The metal impurities in the residual growth catalysts of NCNTs have no impact on the catalytic performance,demonstrating the nature of metal-free catalysis of NCNTs.The optimal process parameters are as follows: 85 oC,4 h,1 MPa,100 mg NCNTs,1,2-dichloroethane as solvent.ACR conversion is 24.8% and AA selectivity is 100% under this reaction conditions,showing an advantage over gas-phase catalytic oxidation of ACR to AA.NCNTs have good recyclability in the liquid-phase oxidation of ACR to AA.The catalytic performance keeps stable after 5 cycles.The study provides a new metal-free catalytic process from ACR to AA.(2)On the basis of the previous work,we found that the participation of cyclohexanone could significantly increase the yield of AA.ACR is an effective co-oxidizing agent for the aerobic Baeyer-Villiger oxidation reaction of cyclohexanone.The co-oxidation of cyclohexanone and ACR produces ?-caprolactone and AA,which are both high-demand chemicals.NCNTs have good catalytic performance and recyclability in this reaction system.The optimal process parameters are as follows: 80 oC,4 h,1 MPa,100 mg NCNTs,1,2-dichloroethane as solvent.We yielded 37.7% ?-caprolactone and 30.0% AA when the molar ratio of ACR to cyclohexanone is 4.NCNTs play a vital role of buffering the radicals in the co-oxidation process of ACR and cyclohexanone.We proved that peroxidacrylic acid is a important intermediate.This study provides a metal-free carbon catalysis technology of co-oxidation of cyclohexanone and ACR.