非晶态铁基固体碱催化剂的酯交换性能

Transesterification Performance of Amorphous Iron-Based Solid Base Catalyst

通过化学还原法和共沉淀法分别制备了非晶态和晶态的FeCeOx/SiO2固体碱催化剂。与晶态的FeCeOx/SiO2相比,非晶态的FeCeOx/SiO2催化剂对梨醇酯与甲醇的酯交换活性显著提高。通过电感耦合等离子体质谱(ICP-MS)、N2吸附-脱附、透射电子显微镜(TEM)结合选区电子衍射(SAED)、X射线衍射(XRD)、X射线光电子能谱(XPS)、CO2-TPD和NH3-TPD等对催化剂进行表征。结果表明催化剂的活性与其碱性密切相关,非晶态FeCeOx/SiO2显示出相对于晶态FeCeOx/SiO2更强的碱性。使用非晶态FeCeOx/SiO2催化剂进行梨醇酯酯交换反应,在130℃下反应10 h,梨醇酯的转化率达到95%,异戊烯醇的选择性达到96%。在重复使用10次后,催化剂活性基本不变。对新鲜的和套用10次后的FeCeOx/SiO2催化剂进行X射线衍射分析,表明该催化剂在套用10次后仍未晶化,证实其具有良好的稳定性,说明该催化剂在非均相催化酯交换反应中具有应用价值。

Both amorphous and crystalline FeCeOx/SiO2 solid base catalysts were prepared by chemical reduction and co-precipitation methods,respectively.The activity of amorphous FeCeOx/SiO2 for the transesterification of prenyl acetate with methanol was remarkably enhanced compared with crystalline FeCeOx/SiO2.The catalysts were characterized by inductively coupled plasma mass spectrometry(ICP-MS),N2 adsorption-desorption,transmission electron microscopy(TEM)in combination with selected area electron diffraction(SAED),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and temperature programmed desorption(CO2-TPD and NH3-TPD).As a result,the activity of the catalysts is found to be closely related to its basicity,and the amorphous FeCeOx/SiO2 shows higher basicity.Prenyl acetate conversion of 95%and prenyl alcohol selectivity of 96%were obtained using amorphous FeCeOx/SiO2 catalyst in transesterification reaction at 130℃for 10 h.The catalyst maintained a high level of activity after 10 cycles of testing.X-ray diffraction analyses of fresh and used FeCeOx/SiO2 catalyst demonstrated that this catalyst is exceptionally stable,which could be of value in industrial application related to heterogeneous catalytic transesterification.