Optimized preparation of Fe_2O_3/Al_2O_3 composite with sol-gel combustion synthesis method based on orthogonal experimental design

摘要

Fe_2O_3/Al_2O_3 composite at the mass ratio of 3:2 was prepared by sol-gel combustion synthesis using urea as fuel. The optimized preparation parameters were determined by the robust orthogonal experimental design (OED) method. Standard L_9(3~4) orthogonal array was adopted, and the four factors were determined as the molar ratio of oxidizer nitrates to fuel urea Ф, relative amount of the deionized water added R_w, ignition temperature and sintering temperature. Range analysis of the relative importance of those four factors on the mean weight loss rate for the reduction of synthesized Fe_2O_3/Al_2O_3 with 50 vol% H_2 indicated that the most influential factor was Ф, sintering temperature, R_w and ignition temperature in the descending order. And the optimized preparation parameters for Fe_2O_3/Al_2O_3 composite were Ф=1, R_w=7.5, ignition and sintering temperatures stabilized as 600°C and 950°C, respectively. Finally, the reaction characteristics of Fe_2O_3/Al_2O_3 prepared by SGCS and the other two reference methods (including sol-gel method and mechanical mixing method) were compared and the results verified that the optimized SGCS was the best option to synthesize Fe_2O_3/Al_2O_3 composite with good reaction performance.