碱金属掺杂对NiFeAlO4载氧体结构及反应特性的影响

采用溶胶-凝胶法和浸渍法制备了碱金属掺杂的尖晶石结构NiFeAlO4载氧体，考察了制备方法、碱金属种类、碱金属掺杂比例对NiFeAlO4载氧体结构、煤化学链燃烧特性和循环稳定性的影响。结果表明，溶胶 凝胶法制备的钾掺杂NiFeAlO4载氧体具有更好的反应性，当载氧体与煤质量比为20∶1时，掺杂质量分数为5% K2CO3的NiFeAlO4载氧体与煤反应的碳转化率为99%，高于NiFeAlO4载氧体与煤反应时的碳转化率（87%）。与NiFeAlO4载氧体相比，掺杂质量分数为5% K2CO3的NiFeAlO4载氧体呈现出更好的循环稳定性，主要归因于碱金属K的掺杂改善了载氧体的反应活性，对载氧体的团聚有抑制作用，且反应前后载氧体晶相结构保持不变。

Effect of Alkali Metal Doping on NiFeAlO4 Oxygen Carrier Structures and Its Coal Chemical Looping Combustion Performance

The alkali metal doped NiFeAlO4 oxygen carrier with spinel structures were prepared via the impregnation and the sol-gel methods. The coal chemical looping combustion reaction and cycling stability of the alkali metal doped NiFeAlO4 oxygen carrier were investigated via considering the factors of preparation methods, the alkali metal type and the alkali metal doping dosage. Results show that potassium doped NiFeAlO4 oxygen carrier synthesized by the sol-gel method possesses superior reactivity. When the mass ratio between oxygen carrier and coal is 20∶1, 99% carbon conversion has been obtained over NiFeAlO4 oxygen carrier doped with 5% (mass fraction) K2CO3, which is much higher than that of the NiFeAlO4 oxygen carrier reacting with coal (87%)。Compared with NiFeAlO4 oxygen carrier, NiFeAlO4 oxygen carrier doped with 5% (mass fraction) K2CO3 exhibited better cyclic stability. The analysis of crystal structures and morphology of NiFeAlO4 oxygen carrier doped with 5% (mass fraction) K2CO3 shows that the grain agglomeration is inhibited by potassium and crystal structures remain unchanged before and after reactions.