基于层状氢氧化物衍生复合氧载体的生物质化学链气化实验研究

摘要

通过低饱和共沉淀法合成了类水滑石结构的层状氢氧化物（ Layered Double Hydroxide， LDH）前驱体，经煅烧获得衍生Cu／Al／Zn、Cu ／Al／Ni、Cu／Al／Ni／Zn高分散复合氧载体。采用XRD、XRF、H2-TPR、SEM及BET等分析手段对氧载体的结构及反应性能进行了表征，并通过固定床反应器开展了氧载体与生物质化学链气化实验。结果表明，合成的三种前驱体都具有典型的水滑石特征衍射峰，且层板稳定。 Cu／Al／Zn前驱体层间厚度为0．2642 nm，Ni2＋引入后，层间距减小。前驱体煅烧后形成的复合氧载体中元素含量与制备试剂基本一致。氧载体中Zn、Ni元素的引入可提升CuO的反应活性，降低H2还原的反应温度，Zn元素与Cu具有更好的协同作用。 Cu／Al／Ni／Zn氧载体在固定床化学链气化中具有较好的碳转化率和气体产率，其碳转化率为82．03％。反应后氧载体比表面积为5．995 m2／g，具有较好的可再生性与抗烧结性，是生物质化学链气化反应较为理想的氧载体。%Layered double hydroxide ( LDH ) precursors with different metal elements were prepared by co-precipitation method at constant pH value; highly dispersed Cu/Al/Zn, Cu/Al/Ni and Cu/Al/Ni/Zn mixed metal oxygen carriers were obtained by calculation of the corresponding precursors.These oxygen carriers were characterized by XRD, XRF, H2-TPR, SEM and nitrogen adsorption and their activity in the chemical looping gasification ( CLG ) of biomass was investigated in a fixed bed reactor.The results indicated that typical hydrotalcite structure appeasr in teh three precursors with stable layer board.The interlayer spacing of Cu/Al/Zn precursor is 0.264 2 nm, larger than that of the Cu/Al/Ni precursor.The oxygen carriers derivedf rom the correspno ding precu rsors display similar elements contents as the preparation reagents.D ue to the synergy among various metals, the Cu/Al/Ni/Zn oxygen carrier shows the highest reaction activity and anti-sintering ability. The addition of Ni and Zn has a positive effect on the activity of CuO and reduce its reduction temperature; Zn shows a better synergistic effect than Ni with Cu.The carbon conversion reaches 82.03% for the CLG of biomass with Cu/Al/Ni/Zn as oxygen carrier;the surface area of Cu/Al/Ni/Zn remanis 5.995 m2/g after the CLG reaction, suggesting that it could be an ideal candidate for the CLG of biomass.