改性铁酸锌催化剂的合成及其丁烯氧化脱氢活性

采用共沉淀法制备铁酸锌催化剂,考察改性元素Mg、B、Zr、Ce、La对铁酸锌催化剂结构和丁烯氧化脱氢性能的影响。采用XRD、TEM和N_2吸附-脱附对镧改性铁酸盐催化剂进行金属元素组成的优化研究,确认镧元素在催化剂中存在的形态和作用。结果表明,La改性铁酸锌催化剂晶粒粒径(20～50) nm,具有较大的比表面,主要活性组分是α-Fe_2O_3和ZnFe_2O_(4,)催化剂的活性随着Fe含量的升高而升高,n(Fe)∶n(Zn)∶n(La)=4∶1∶1催化剂具有最高的催化活性,反应温度380℃时,其TOF值2.1×10~(-3) mol_(butene)·mol_(surface-Fe)·s~(-1)。

Synthesis of modified zinc ferrite catalyst and its catalytic activity in the oxidative dehydrogenation of butene

Zinc ferrite catalysts were prepared by coprecipitation method,and the modification of zinc ferrite catalysts with Mg,B,Zr,Ce and La,and the effect of these elements on the structure and catalytic performance of zinc ferrite catalysts were investigated,respectively.The lanthanum modified ferrite catalysts with a higher catalytic activity for the oxidative dehydrogenation of butene to butadiene were studied by XRD,TEM and N₂ adsorption-desorption to screen optimal metal composition of catalyst,and clarify the morphology and function of lanthanum in the catalysts.La-modified zinc ferrite catalyst possessed a large specific surface area with a crystal size of (20-50) nm.It had been found that the active components of the La-modified ferrite catalysts were α-Fe₂O₃ and ZnFe₂O₄.The activity of catalyst increased with increasing Fe content.The La-modified catalyst with n(Fe):n (Zn):n (La)=4:1:1 possessed the highest activity with a turnover frequency (TOF) of 2.1×10^-3 mol_butene·mol_surface-Fe·s^-1 at 380 ℃。