铁镍载氧体在煤焦化学链气化中的改性研究

Study on modification of iron-nickel oxygen carrier in coal char chemical looping gasification

文中采用溶胶-凝胶法制备一系列铁镍载氧体,应用于煤焦化学链气化过程以制备合成气。利用H_(2)-TPR、XRD和SEM等表征手段考察载氧体的物理化学性质,并基于煤焦化学链气化反应固定床实验探究NiO质量分数、循环次数以及负载惰性载体等参数对铁镍载氧体反应性能的影响。实验结果表明:NiO的添加能够有效改善载氧体的反应活性,但当添加量高于质量分数20%时,气化性能显著下降;铁镍载氧体形成的NiFe_(2)O_(4)尖晶石结构是改善反应活性的关键,但在高温循环过程中该结构易发生晶相分离,导致载氧体反应活性下降以及团聚烧结现象的发生;惰性载体的加入能够有效抑制铁镍载氧体的烧结。

A series of iron-nickel oxygen carriers were prepared by the sol-gel method and applied to the chemical looping gasification process of coal char to produce syngas.The physical and chemical properties of the oxygen carriers were investigated by the analytical means of H_(2)-TPR,XRD and SEM.The effects of different NiO content,different cycle times and different inert supports on the reaction performance of the iron-nickel oxygen carrier were explored through the fixed bed experiment of coal char chemical looping gasification reaction.The experimental results show that the addition of NiO can effectively improve the reaction activity of the oxygen carrier,and remarkable decline in gasification performance can be observed when the amount of NiO added in the iron-nickel oxygen carrier is more than mass fraction 20%.The NiFe_(2)O_(4) spinel structure formed by the iron-nickel oxygen carrier is the key to improving the reaction activity.However,a phase separation of the crystal is easy to occur during the recycling in a high temperature,which leads to the decrease of oxygen carrier reaction activity and the occurrence of agglomeration and sintering.The addition of the inert support can effectively inhibit the sintering of the iron-nickel oxygen carrier.