溶胶凝胶Fe_2O_3/Al_2O_3氧载体与甲烷的循环反应性研究

MULTIPLE-CYCLE REACTION PERFORMANCE OF SOL-GEL-DERIVED Fe_2O_3/Al_2O_3 OXYGEN CARRIER WITH METHANE

高性能的氧载体是化学链燃烧技术实施的关键。本文采用溶胶凝胶法制备的Fe_2O_3/Al_2O_3氧载体,在固定床反应器中研究了它与CH_4/空气在900℃下的循环反应性,并利用XRD、ESEM和BET对反应前后的氧载体进行了物化表征。试验结果表明,溶胶凝胶法制备的Fe_2O_3/Al_2O_3氧载体具有良好的循环反应能力。随着循环次数的增多,氧载体与CH_4反应生成CO_2的最大浓度值从44.9%～51.2%逐渐增加,氧载体的还原氧化反应性逐渐增大。循环反应后,氧载体表面出现了一定程度的烧结现象,氧载体的比表面积、内孔容积和平均孔径均有所减小,但仍足够大。这些结果初步证明采用溶胶凝胶法制备的Fe_2O_3/Al_2O_3氧载体具有实现气体燃料化学链燃烧技术的可行性,用于双连通循环流化床的化学连燃烧过程时,床料量约为51～212 kg/MWth,循环倍率约为8.2 kg/s,MWth。

High-performance oxygen carriers are the key point for chemical looping combustion technology. The circle reactivity of Sol-gel-derived Fe2O3/Al2O3 oxygen carriers and CH4/air is researched in a fixed-bed reactor at the temperature 900℃ in this paper. X-ray diffraction （XRD）, scanning electron microscope （SEM）, and N2 adsorption-desorption （BET） methods are utilized to characterize the physicochemical properties of oxygen carriers before and after the circular reaction. The experimental results show that Fe2O3/Al2O3 demonstrates extremely good recyclability of the reduction-oxidation reaction. As the circulation progresses, the maximum concentration of CO2 is increasing from 44.9% to 51.2% and the reduction-oxidation reactivity of the oxygen carrier also increases gradually. After circle reduction-oxidation reactions, the sintering behavior is observed on the surface of the particles, and the specific surface area, volume inside the pore and average pore size of the oxygen carrier decrease, but they are still large enough. These experimental results prove that the sol-gel-derived Fe2O3/Al2O3 is capable of being used in chemical looping combustion fueled by CH4.