Study On Oxidation Of Toluene To Benzoic Acid Catalyzed By VOTPP

As a common fine chemical,composed of carboxyl group and benzene ring directly,benzoic acid is widely used as preservative,inhibitors,feed acidizing agent,moldinhibitor,resin plasticity agent and deodorant.The oxidation of toluene is one of the important ways of synthesizing benzoic acid in industry.In this paper,the tetraphenyl vanadium oxygen porphyrin(VOTPP)was synthesized by a simple two synthetic method.We first reported the liquid-phase oxidation of toluene to benzoic acid catalyzed by VOTPP.The results showed that VOTPP catalyst exhibited obvious activity for toluene oxidation and high selectivity of benzoic acid.Compared with the traditional system,this process has reduced the reaction temperature and pressure,and toluene could be converted to benzoic acid without the use of solvents,eliminating the possibility of acidic impurities.At the same time,the high benzoic acid selectivity,simple oxidation product detection method,and no need for complex operations are the advantages of this study.The molecular structures of tetrahenylporphyrinate(TPP)and VOTPP were characterized by UV-vis,IR,TG,XPS,HNMR,at el.The main oxidation products were determined by a liquid-mass spectrometer and a complete product analysis system was established.The content of benzoic acid was determined by liquid chromatography,and the equation of the relationship between benzoic acid content and peak area was established,W= 126.26 A +0.5798,R=0.9999.The relationship between peak area and content is linear in a certain concentration range.In the toluene-oxygen liquid-phase catalytic oxidation,the optimal process conditions of the reaction were determined by the control variable method.The effects of different catalyst dosage,reaction temperature,pressure and reaction time on toluene oxidation products were explored.The results showed that under the conditions of reaction temperature 145oC,pressure 0.8MPa,and reaction time 4h,the conversion rate of toluene was 23%,and the selectivity of benzoic acid was 86%.Compared with traditional catalysts,the temperature and pressure of toluene oxidation catalyzed by tetraphenylvanadium oxyporphyrin are lower,and the high-efficiency conversion of toluene can be achieved without using a solvent,eliminating the possibility of acidic impurities and eliminating the solvent recovery process.