The Composite Oxygen Carries Using Iron Ore Concentrate And Aluminum As Raw Materials By In Situ Reduction

Chemical looping combustion is a new type of combustion technology that is different from traditional combustion.It uses oxygen carriers to achieve oxygen transfer between fossil fuels and air.The products are only CO₂and H₂O,which can reduce energy consumption and achieve high-concentration CO₂capture.The Bayan Obo iron ore concentrate in Inner Mongolia has the advantages of low price,large reserves,and environmental friendliness.It is an ideal raw material for the preparation of oxygen carriers.Therefore,this paper uses Bayan Obo iron ore concentrate as the oxygen carrier to conduct a chemical chain combustion feasibility study.Aiming at the problem of sintering and agglomeration of the iron concentrate oxygen carrier during multiple cycles at high temperature,the in-situ reduction method was used to prepare aluminum-added modified iron concentrate oxygen carriers with different Al:Fe ratios.The chemical chain combustion characteristics of the modified oxygen carrier have the following main results:（1）The reaction between the oxygen carrier of iron concentrate and CO is mainly concentrated after 800℃.In the 10 thermoreduction-oxidation cycle experiments at850℃,the oxygen carrier has a stable weight loss of about 4%after four reactivity activation processes.SEM It shows that the iron ore concentrate oxygen carrier has sintered and surface particles agglomerate.（2）51 reduction-oxidation cycles under the CO atmosphere of the iron concentrate oxygen carrier were carried out on the fixed bed.The iron concentrate oxygen carrier showed good cycle stability at 850℃,and raising the reaction temperature can speed up the oxygen carrying capacity.The rate of activation of the reaction activity of the body,the cumulative conversion rate of CO is stable at 64%to 65%,the cumulative conversion rate of CO at 900℃and 950℃starts to decrease after the 31_stand 11_thcycles,respectively,and the reaction activity decreases.SEM and XRD It shows that after 900℃,the iron ore concentrate oxygen carrier undergoes internal sintering and agglomeration during multiple cycles,resulting in a decrease in reaction activity.（3）In order to improve the ability of the iron concentrate oxygen carrier to resist sintering and agglomeration at high temperature and increase the reaction activity,different Al:Fe material ratios were prepared by the in-situ reduction method,and the modified iron concentrate oxygen carrier was added with Alto determine the optimal load.The Al:Fe material ratio of the oxygen body is 2:8.The modified Al₂Fe₈oxygen carrier showed good cyclic stability after the activation process in 10 thermoreduction-oxidation cycle experiments,and the weight loss was stable at about 4.2%.The kinetic analysis of the iron concentrate oxygen carrier before and after modification It is found that the addition of Alcan reduce the apparent activation energy of the iron concentrate oxygen carrier.（4）The modified Al₂Fe₈oxygen carrier showed good cycle stability in 51reduction-oxidation cycle experiments,and increasing the reaction temperature had no effect on the activation process of the oxygen carrier.The cumulative conversion rate of CO at 850℃,900℃and 950℃is 68%～70%,78%～79%and 85%～86%,respectively,which is higher than the oxygen carrier of iron ore.Increasing the reaction temperature can improve the modification.Cumulative CO conversion rate of the oxygen carrier.The XRD and SEM-EDS analysis of the fresh Al₂Fe₈oxygen carrier show that the inert support Al₂O₃formed by the addition of Alis evenly distributed in the oxygen carrier,forming a good pore structure inside the oxygen carrier,which is beneficial to CO and oxygen The reaction inside the body,after multiple reduction-oxidation cycles,Al₂O₃and Fe₂O₃in the oxygen carrier form an AlFe₂O₄spinel structure compound that can improve the mechanical properties and sintering resistance of the oxygen carrier.