Study On P-hydroxybenzaldehyde Synthesis By Catalytic Oxidation Of P-cresol

p-Hydroxybenzaldehyde(PHBA)is an important fine chemical intermediate,extensively used in many fields,such as medicines,pestisides,spice,petrochemical industry,electroplatiny,liquid crystals,photosensitive polymer and so on.The way of PHBA synthesis by catalytic oxidation of p-cresol has outstanding commercial prospect,for its few processes,simple operations,high yield,higher purity and few three wastes.LDHs and LDO have some excellent characteristics for their special structure.There is considerable interest in synthetizing PHBA by catalytic oxidation of p-cresol,using them as catalyst.In this paper,CoCuAl-LDHs and CoCuFe-LDHs were prepared by simple traditional coprecipitation method,which were calcinated subsequently with high temperature and CoCuAl-LDO and CoCuFe-LDO were prepared.These LDHs and LDO were used as catalyst respectively for catalytic oxidation of p-cresol to PHBA.The influence factors on the percent conversion of p-cresol have been investigated,such as the form of catalyst,reaction temperature,reaction time,the amount of base and solvent,etc.CoCuAl-LDO(Co:Cu:Al=3:1:1,mole ratio)and CoCuFe-LDO(Co:Cu:Fe=3:1:1,mole ratio)calcinated at 450? have high catalytic activity.The best condition for using such LDO as catalyst and converting p-cresol into PHBA wasobtained.The conversion of p-cresol was about 99%at 65 ?,catalyst/p-cresol=0.05(mass ratio),p-cresol:NaOH:methanol=1:3:18(mole ratio),reaction 8h.It was found that CoCuAl-LDHs and CoCuFe-LDHs have high catalytic activity,sinilarly to CoCuAl-LDO and CoCuFe-LDO.Under the same conditions,The conversion of p-cresol was also about 99%by using them as catalyst.Furthermore,the service life of catalyst was examined subsequently.Such layered metal materials have good catalyst life.The experimental results indicate that LDHs(Co:Cu:Al=3:1:1,Co:Cu:Fe=3:1:1,mole ratio)and LDO(LDHs calcinated at 450?)have good catalytic activity for PHBA synthesis by catalytic oxidation of p-cresol,and have great industrial value.