酸改性复合氧载体CaSO4-CaO的反应性能

摘要

CaSO4-CaO combined oxygen carrier was prepared by mixing mechanically. The CaSO4was modified with different types of acid. The characterizations and evaluation of modified CaSO4-CaO oxygen carrier were studied using XRD,H2-TPR,and a small tube furnace reactor. The effect of acid types on CaSO4reductive reactivity,CO2generation,SO2and COS releases were studied. It was founded that the reactivity of acid-modified CaSO4-CaO oxygen carrier was obviously higher than that without preparation; the use of acid mainly increased the selectivity of side competitive reactions of CaSO4reductions,which resulted in the emission of SO2increased remarkably,and the release of COS dropped somewhat. CaSO4-CaO combined oxygen carrier,which CaO was from the CaCO3calcination and CaSO4was modified with HNO3,had good reactivity. So its cycle performance was studied. However,the reactivity decreased after 6th reduction-oxidation cycle. During the cycle test,SO2was the main gas sulfides which was released during reduction phase.%将CaO添加到经不同酸改性后的CaSO4氧载体中来制备CaSO4-CaO复合氧载体.采用XRD、H2-TPR、CO小型卧式管式炉开展恒温反应和循环实验,对氧载体进行表征和评价.主要研究了酸的种类对CO2生成、气体硫化物的释放及复合氧载体循环反应性能的影响.结果表明:酸化的复合氧载体的氢气还原活性均明显优于未经改性过的CaSO4,相比无酸化处理的CaSO4氧载体,酸化后的CaSO4-CaO复合氧载体,特别是HCl酸化,主要是提高了CaSO4竞争还原副反应的选择性,导致主要气体硫化物SO2释放显著增加,而COS释放略有降低.以CaCO3煅烧得到的CaO与经HNO3改性的CaSO4进行机械混合制得的复合氧载体具有较好的反应活性,但是经过6次循环反应后,还原反应活性下降;循环反应中,气体硫化物主要来自于CaSO4在还原阶段释放出的SO2.