Oxidation Of Liquid-phase Toluene To Benzyl Alcohol By Manganese Based Catalyst

In this paper,the synthesis of benzyl alcohol by toluene liquid-phase heterogeneous catalytic oxidation is mainly studied.As an important fine chemical product,benzyl alcohol has a wide range of applications in many fields such as spices and medicines.At present,benzyl alcohol is mainly produced by the benzyl chloride hydrolysis method in my country’s industry.This method has the disadvantages of equipment corrosion,environmental pollution,and product containing chlorine,which seriously limits the development of the benzyl alcohol industry in the fields of spices and the like.The heterogeneous catalytic oxidation of toluene to benzyl alcohol as a green and environmentally sustainable synthetic route has important value.In this paper,the catalytic performance of activated metal manganese oxide supported catalysts using carbon nanotubes（CNTs）/nitrogen-doped carbon nanotubes（NCNTs）as carriers in heterogeneous catalytic oxidation of toluene was investigated.It was found that the catalyst can not only improve manganese oxide The problem of catalyst agglomeration can also control the excessive oxidation of toluene and improve the selectivity of benzyl alcohol with good performance.The main contents are as follows:（1）Solvothermal synthesis of metal manganese oxide catalyst was applied to the selective oxidation reaction of toluene.The influence of the amount of reducing agent added and the reaction temperature on the change of catalytic activity caused by the change of catalyst morphology during the preparation of the catalyst by solvothermal method was studied and analyzed.The results prove that the amount of reducing agent and ethylene glycol the reaction temperature will accelerate the reduction rate of high-valent manganese ions in the reaction system,and it is very critical for the synthesis of manganese oxides with different crystal phases.also has a very important effect on the composition of manganese oxide.The catalysts prepared under different reaction temperatures and reducing agents were used in the toluene reaction study.It was found that when the hydrothermal temperature was 160°C and the amount of ethylene glycol added was 1 m L,the synthesized catalyst had the highest activity and the main component of the catalyst was Mn₃O₄.The toluene conversion rate was 7.82%,and the benzyl alcohol selectivity was 46.32%.（2）Carbon nanotubes（CNTs）/nitrogen-doped carbon nanotubes（NCNTs）were used as carriers to support metal manganese oxides in the selective oxidation of toluene.Experiments show that the addition of carbon nanotubes and nitrogen-doped carbon nanotubes will make the catalyst exhibit higher catalytic activity and selectivity in the reaction of selective oxidation of toluene to benzyl alcohol compared to metal manganese oxides,mainly because of the support The addition of can effectively improve the problem of metal oxide agglomeration.In the study of catalytic oxidation of toluene,the effects of CNTs/NCNTs addition amount,catalyst amount,oxygen flow rate,reaction temperature,reaction time,n（tert-butyl hydrogen peroxide）:n（toluene）and other factors on the reaction activity were investigated.After the final optimization,it was found that when using carbon nanotubes as the carrier,toluene 10 m L,t-butyl hydroperoxide 1m L,oxygen flow rate 15 m L/min,reaction temperature 363 K,reaction time 12h,toluene conversion rate can reach 24.63%,benzyl alcohol production The rate is 10.72%.When using nitrogen-doped carbon nanotubes as the carrier,toluene10m L,tert-butyl hydrogen peroxide 1m L,oxygen flow rate 15 m L/min,reaction temperature 353 K,reaction time 8 h,toluene conversion rate can reach 26.74%,the yield of benzyl alcohol is 12.08%,NCNTs have higher catalytic activity mainly because nitrogen atoms in NCNTs can improve the electronic characteristics of the catalyst surface,more conducive to toluene adsorption and oxygen activation on the catalyst surface,and more conducive to increase under the control of reaction temperature Selectivity of reaction product benzyl alcohol.