Preparation and performance of the Fe2O3/ATP oxygen carriers in coal chemical looping combustion
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摘要: 以天然凹凸棒(ATP)为载体,分别利用机械混合法、浸渍法和溶胶-凝胶法制备了3种铁基复合载氧体。利用X射线衍射(XRD)、能谱(EDS)、N2-吸附脱附等温线等对其进行物化表征,并在900 ℃流化床中考察其煤化学链燃烧反应性能。结果表明,ATP能显著增加载氧体比表面积和抗磨损能力,并对煤转化过程有催化作用,其与Fe2O3的协同作用使初始碳转化速率显著提高。溶胶-凝胶法制备的U-Fe4ATP6表面Ca元素含量为4.3%,比表面积为4.920 7 m2/g,均高于其他两种载氧体,表现出更高的催化性能和反应活性:初始碳转化速率为0.168 min-1,平均CO2浓度为98.6%,燃烧效率为98.7%。20次反应后,U-Fe4ATP6催化性能略有降低,对应的初始碳转化速率降至0.108 min-1,停留时间t95延长到18 min;且能维持较高的反应活性,对应的CO2捕集效率和燃烧效率分别稳定在98.6%和96.7%。Abstract: Through mechanical-mixing, impregnating and sol-gel methods, Fe2O3-based oxygen carriers (OC) were prepared with natural attapulgite (ATP) as an inert support and characterized by X-ray diffraction (XRD), energy dispersive spectrometer (EDS), and nitrogen adsorption-desorption measurements. The reactivity of Fe2O3-based oxygen carriers (Fe2O3/ATP OCs) in coal chemical looping combustion (CLC) was investigated in a fluidized-bed reactor at 900 ℃ by using steam as the gasification agent. The results indicated that the surface area and attrition resistance of Fe2O3/ATP OCs are improved significantly by using ATP as the support. Owing the synergy between ATP and Fe2O3, both are catalytic active, carbon conversion is enhanced significantly. ATP is an appropriate support for Fe2O3 oxygen carriers, whereas the sol-gel method gives the carriers best performance. U-Fe4ATP6 prepared by the sol-gel method, with a surface area of 4.920 7 m2/g and Ca content of 4.3%, exhibits much better performance than other two oxygen carriers. When used in CLC, the initial carbon conversion rate reaches 0.168 min-1, with an average CO2 concentration of 98.6% and a combustion efficiency of 98.7%. The catalytic activity of U-Fe4ATP6 is slightly decreased after twenty cycles; the initial carbon conversion rate is decreased to 0.108 min-1 and the residence time (t95) is extended to 18 min, whereas the CO2 capture efficiency and combustion efficiency remain at about 98.6% and 96.7%, respectively.
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Key words:
- coal /
- chemical-looping combustion /
- Fe2O3-based oxygen carrier /
- attapulgite /
- support /
- fluidized bed
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ADANEZ J, ABAD A, GARCIA-LABIANO F, GAYANP,de DIEGO L F. Progress in chemical-looping combustion and reforming technologies[J]. Prog Energy Combust, 2012, 38(2): 215-282. 王保文, 赵海波, 郑瑛, 柳朝晖, 郑楚光, 晏蓉. 惰性载体Al2O3对Fe2O3及CuO氧载体煤化学链燃烧的影响[J]. 中国电机工程学报, 2011, 31(32): 53-61. (WANG Bao-wen, ZHAO Hai-bo, ZHENG Ying, LIU Chao-hui, ZHENG Chu-guang, YAN Rong. Effect of Inert Support Al2O3 on the chemical looping combustion of coal with Fe2O3 and CuO-based oxygen carrier[J]. Proc CSEE, 2011, 31(32): 53-61.) GUO Q, CHENG Y, LIU Y, JIA W, RYU H. Coal chemical looping gasification for syngas generation using an iron-based oxygen carrier[J]. Ind Eng Chem Res, 2014, 53(1): 78-86. 程煜, 刘永卓, 田红景, 郭庆杰. 铁基复合载氧体煤化学链气化反应特性及机理[J]. 化工学报, 2013, 64(7): 2587-2595. (CHENG Yu, LIU Yong-zhuo, TIAN Hong-jing, GUO Qing-jie. Chemical-looping gasification reaction characteristics and mechanism of coal and Fe-based composite oxygen carriers[J]. CIESC J, 2013, 64(7): 2587-2595.) HOSSAIN M M, DE LASA H I. Chemical-looping combustion (CLC) for inherent CO2 separations-a review[J]. Chem Eng Sci, 2008, 63(18): 4433-4451. CAO J L, SHAO G S, WANG Y, LIU Y, YUAN Z Y. CuO catalysts supported on attapulgite clay for low-temperature CO oxidation[J]. Catal Commun, 2008, 9(15): 2555-2559. ADANEZ J, de DIEGO L F, GARCIALABINAO F, GAYAN P, ABAD A, PALACIOS J M. Selection of oxygen carriers for chemical looping combustion[J]. Energy Fuels, 2004, 18(2): 371-377. ZHANG J, GUO Q, LIU Y, CHENG Y. Preparation and characterization of Fe2O3/Al2O3 using the solution combustion approach for chemical looping combustion[J]. Ind Eng Chem Res, 2012, 51(39): 12773-12781. 梅道锋, 赵海波, 马兆军, 郑楚光. Fe2O3/Al2O3氧载体制备方法的研究[J]. 燃料化学学报, 2012, 40(7): 795-802. (MEI Dao-feng, ZHAO Hai-bo, MA Zhao-jun, ZHENG Chu-guang. Preparation method study on Fe2O3/Al2O3 oxygen carrier[J].J Fuel Chem Technol, 2012, 40(7): 795-802.) ASTM D 5757-00, Standard test method for determination of attrition and abrasion of powdered catalysts by air jets[S]. MASTELLONE M L, ARENA U. Carbon attrition during the circulating fluidized bed combustion of a packaging-derived fuel[J]. Combust Flame, 1999, 117(3): 562-573. 杨景标, 蔡宁生, 张彦文. 催化剂添加量对褐煤焦水蒸气气化反应性的影响[J]. 燃料化学学报, 2008, 36(1): 15-22. (YANG J B, CAI N S, ZHANG Y W. Effect of catalyst loadings on the gasification reactivity of a lignite char with steam[J]. J Fuel Chem Technol, 2008, 36(1): 15-22.) LI X, HAYASHI J I, LI C Z. Volatilisation and catalytic effects of alkali and alkaline earth metallic species during the pyrolysis and gasification of Victorian brown coal. Part VII. Raman spectroscopic study on the changes in char structure during the catalytic gasification in air[J]. Fuel, 2006, 85(10): 1509-1517. 彭康, 王亦飞, 金渭龙, 吴超琦, 王辅臣. 硝酸钙对内蒙古褐煤热解和气化特性的影响[J]. 燃料化学学报, 2013, 41(2): 144-150. (PENG Kang, WANG Yi-fei, JIN Wei-long, WU Chao-qi, WANG Fu-chen. Effects of calcium nitrate on pyrolysis andgasification behavior of lignite from Inner Mongolia[J]. J Fuel Chem Technol, 2013, 41(2): 144-150.)
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