| Selective oxidation is one of the privileged ways in transformation of hydrocarbons to more valuable and more useful products, such as alcohol, aldehyde, acid and other oxygenates. And it is also one of the important ways to exploit hydrocarbons. The environment concerns and regulation are getting more and more serviceable, a lot of efforts and process have been accomplished in the environment benign and sustainable industrial manufacture of fine and intermediate chemicals in recent years.This disquisition summarized the development of selective oxidation of hydrocarbons, especially about oxidation of m-xylene to m-toluic acid and isophthalic acid. It was found that the catalyst CoMnCu/γ-Al2O3 had excellent activity in partial oxidation of m-xylene.The CoMnX/γ-Al2O3 (X-Cu/Ag/Ni/V/Mo/Fe) catalyst was prepared by metals cobaltic salt and manganic salt as main active components, X salt as promoter, andγ-Al2O3 as carrier using synchronous impregnation method. The catalysts were evaluated in selective oxidation of m-xylene in gas phase. And the catalysts were characterized by BET analysis, XPS, XRD, SEM methods. The optimum conditions of catalyst preparation were achieved according to the results of catalyst characterizations and the reaction of oxidation of m-xylene. The effects of preparation conditions on catalytic performance were analyzed. Results show that the treating ofγ-Al2O3, the ratio of main catalysts, X species, the calcined temperature and time of the catalyst have great influence on catalytic performance. The best condition of catalyst: Mn(NO3)2 and Co(NO3)2·6H2O are the main catalysts; Their total content is 4.8%(count by CoO); Co/Mn =1.5/1(mol); The third component is Cu(NO3)2 and its content is 15%(mol ratio of the main catalyst); Calcination temperature is 700℃; Calcination time is 4.5h.Under the optimum condition of catalyst preparation, the conditions of oxidation reaction were optimized. The best result is the conversion of m-xylene reaches 42.0%, the selectivity for m-toluic acid is 95.5%, under normal atmosphere. |
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