Fe_2O_3/γ-Al_2O_3催化乙醇脱水制乙烯

Catalytic Dehydration of Ethanol to Ethylene over Fe_2O_3/γ-Al_2O_3

采用浸渍法制备了一系列不同Fe_2O_3负载量的Fe_2O_3/γ-Al_2O_3催化剂,考察了它们在乙醇脱水制乙烯反应中的催化性能,通过XRD、BET和NH_3-TPD等手段对催化剂进行了表征,并对Fe_2O_3负载量、反应温度、乙醇含量和液态空速等工艺条件进行了优化。实验结果表明,Fe_2O_3可较好地分散在γ-Al_2O_3载体上,Fe_2O_3的引入使催化剂的孔体积和孔径都有所增大,表面酸量、酸密度和强度分布发生明显变化。Fe_2O_3负载量为0.5%的Fe_2O_3/γ-Al_2O_3催化剂的表面总酸量和酸密度最大,尤其是中强酸含量最多,其催化乙醇脱水制乙烯的性能最佳。以Fe_2O_3负载量为0.5%的Fe_2O_3/γ-Al_2O_3为催化剂,在反应温度380℃、原料乙醇质量分数92.4%、液态空速1.2h^(-1)的反应条件下,乙烯收率可达98.5%。

A series of Fe2O3/γ-Al2O3 catalysts with different iron oxide loading were prepared through impregnation method and their catalytic activities for dehydration of ethanol to ethylene were studied. Effects of iron oxide loading, reaction temperature, ethanol concentration and LHSV on the dehydration were investigated. The catalysts were characterized by means of XRD, BET and NH3-TPD. It was found that through loading of Fe2O3 , both the pore volume and the pore diameter of the γ-Al2O3 could be enlarged, and the surface acid amount, acid density and acid strength distribution of the catalysts were changed obviously. The surface acid amount and the acid density of the Fe2O3/γ-Al2O3 catalyst with Fe2O3 loading 0.5% （mass fraction） were the largest, especially the medium acid amount. And the catalyst showed the best catalytic performance for the dehydration of ethanol to ethylene. Under the optimized reaction conditions ： reaction temperature 380 ℃（2, ethanol mass fraction 92.4 % and LHSV 1.2 h^-1 , ethylene yield could reach 98.5% over the Fe2O3/γ-Al2O3 catalyst with Fe2O3 loading 0.5%.