Vapor Phase Alkylation Of Phenols With Methanol Over Iron Based Composite Oxides Catalyst

Phenols alkylation is one of the major fine chemical reactions in organic reactions and is widely used in organic industry,petrochemical industry,pigments,pesticides and so on.Iron-based composite oxides have been widely used in catalytic alkylation of phenols by virtue of its simple preparation,mild reaction conditions,and high selectivity of target products.In this paper,iron-based composite oxides were synthesized and characterized,with which catalytic performance in gas phase alkylation of m-cresol and phenol was evaluated.The whole work mainly includes the following two aspects:1.Preparation and characterization of nanocomposite oxides Fe2O3-SiO2-CuO series:Fe2O3-SiO2-CuO samples with different proportion were prepared via co-precipitation,and characterizations such as XRD?SEM?BET and NH3-TPD were performed to analyze crystal phase,grain size,specific surface area,pore volume,pore size,and acidity distribution on its surface.Catalytic performance of m-cresol alkylation and phenol alkylation under different catalysts were investigated and compared.The results show that catalysts prepared with ferric nitrate as iron source,n(Fe)/n(Cu)= 200/1,precipitation pH of 8,and catalyst calcination temperature of 550 ? have the preferable performance for catalytic alkylation reaction.Samples prepared under the above conditions exhibit ?-Fe2O3 crystal phase with an average grain size of 20 nm,relatively large specific surface area,pore volume,and suitable pore sizes.The catalyst surface is mainly covered with moderate amount of medium strength acid sites.2.Synthesis of 2,3,6-trimethylphenol and 2,6-xylenol:the conversion of raw materials and selectivity of the desired product were used as the evaluation indexes to test catalytic performance of iron-based catalysts in alkylation reactions The results show that the activity of Fe2O3-SiO2-CuO series catalysts is significantly higher than other catalysts,especially for samples with n(Fe)/n(Cu)= 200/1.The preferable reaction conditions for m-cresol alkylation catalyzed by Fe200Si5Cu1 are:atmospheric pressure,reaction temperature 340 ?,n(m-cresol):n(methanol):n(water)= 1:5:1.5,LHSV = 0.7 h-1.Under the preferable reaction conditions,the conversion of m-cresol was 100%,and the selectivity of 2,3,6-tricresol was 97.90%.In the phenol alkylation,the preferable reaction conditions are as follows:reaction temperature 340 ?,n(phenol):n(methanol):n(water)= 1:6:1.75,LHSV = 0.7 h-1.Under this condition,the conversion of phenol was 98.40%,and the selectivity of 2,6-xylenol and o-cresol was 87.72%and 10.20%separately.