气体燃料化学链燃烧技术中的溶胶凝胶Ni基氧载体研究

高性能氧载体是实现具有CO2富集特性的化学链燃烧技术的关键。选用Ni(NO3)2和Al(OC3H7)3为主要原料，匹配合适的实验操作参数，通过溶胶 凝胶法制备了NiO/NiAl2O4氧载体，其中60%NiO含量、1300℃烧结6h的该种氧载体物化指标较好。在热重分析上研究了NiO/NiAl2O4氧载体与甲烷/空气的还原 氧化反应性，利用XRD、SEM和BET对反应前后的氧载体进行表征。结果表明，制备的氧载体具有良好的还原 氧化反应循环能力。随着循环次数的增多，每次还原阶段被还原的程度缓慢加深，每次氧化阶段被氧化的程度逐渐下降，且还原加深幅度和氧化下降的幅度均逐渐减小，整体上其循环反应性呈缓慢增加的趋势。循环反应过程中，氧载体颗粒间无任何烧结，仍然保持为多孔结构。这些结果初步证明采用溶胶凝胶法制备的NiO/NiAl2O4氧载体具有实现气体燃料化学链燃烧技术的可行性。

NiO/NiA l2 O4 oxygen carriers prepared by sol-gel for chemical-looping combustion fueled by gas

Chemical looping combustion with inherent CO2 enrichment depends on high powered oxygen carriers. Ni(NO3)2 and Al(OC3H7)3 are selected as main raw materials to prepare sol-gel derived NiO/NiAl2O4, by matching appropriate experimental parameters. The oxygen carrier with a mass content of 60% NiO, a sintering temperature of 1300℃, and a sintering time of 6h performs comparatively good physicochemical properties. The circular reduction oxidation reaction between NiO/NiAl2O4 and methane/air has been investigated with help of a thermogravimetric analyzer (TGA). X-ray diffraction (XRD), scanning electron microscope (SEM), and N2 adsorption desorption (BET) methods were utilized to characterize the physicochemical properties of the fresh and used oxygen carriers. The experimental results show that the sol-gel derived NiO/NiAl2O4 oxygen carriers demonstrate an extremely good recycling ability of reduction oxidation reaction. The reduction of NiO occurs in the presence of CH4, and the reduced Ni is oxidized to NiO in air. As the circulation proceeds, the reduction degree is gradually intensified and the oxidation degree is gradually alleviated. The rates of the reduction intensification and the oxidation alleviation decrease gradually, and then the reduction oxidation reactivity of the oxygen carriers increases by degrees. The sintering behavior between different particles is not observed, and the porous beehive structure of the particle is maintained after several circle reduction oxidation reactions. These experimental results prove that the sol gel derived oxygen carrier NiO/NiAl2O4 is capable of being equipped by chemical looping combustion fueled by CH4.