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氧化铈高温煤气脱硫剂的制备与活性评价

Preparation and Evaluation of Cerium Oxide as Hot Gas Desulfurizer

【作者】 高春珍

【导师】 李春虎; 樊惠玲;

【作者基本信息】 太原理工大学 , 采矿工程, 2004, 硕士

【摘要】 煤炭是世界上最丰富的化石燃料资源,整体煤气化联合循环发电(IGCC)技术是二十一世纪最具有发展前景的一项高效洁净煤技术。高温煤气脱硫是IGCC的关键技术。而脱硫剂的再生是制约高温煤气脱硫技术工业化的主要问题之一。氧化铈脱硫剂是新型的第二代高温煤气脱硫剂。由于其在再生的过程中直接产生单质硫这一优势,近几年来受到人们广泛的关注。 本论文采用硝酸铈、赤泥为主要原料,膨润土作为结构助剂,制备了氧化铈和铁铈复合高温煤气脱硫剂。考察了氧化铈脱硫剂制备条件对脱硫剂的机械强度、孔容和脱硫性能的影响;在固定床反应器中对制备出的氧化铈脱硫剂在模拟真实Texaco煤气气氛中进行了还原与硫化实验;并对铁铈复合脱硫剂进行了硫化、再生性能的研究;通过BET、XRD等测试手段,对有代表性的新鲜及硫化样品进行了物性表征。得出以下几个主要结论: 实验证明:使用二氧化铈脱硫剂可以成功地进行高温煤气粗脱硫,尤其是在强还原性的煤气中。 在500℃-800℃的范围内,随着焙烧温度的升高,氧化铈脱硫剂的比表面积迅速增大,孔容也大幅度上升,机械强度增加。 适量造孔剂的加入,改善了氧化铈脱硫剂的脱硫活性,但过量的造孔剂则影响脱硫剂的强度。 煤气含有的水分对氧化铈脱硫剂的还原与硫化有抑制作用。 氧化饰高温煤气脱硫剂的粒度对CeO:脱硫剂的脱硫性能影响很大。小颗粒脱硫剂的脱硫性能明显高于大颗粒脱硫剂。 赤泥的加入对二氧化饰的晶相结构基本没有影响,可明显改善脱硫剂的脱硫性能。 铁饰复合脱硫剂在NZ、O:含量分别为95%、5%、再生温度为500℃再生条件下再生,再生完全,但单质硫回收率低。 CeO:高温煤气脱硫剂的还原价态约为+3,与膨润土中的硅结合形成了Ce4.667(5104)O,与Ceon(1 .5(n<2)相比,Ce4667(5104)O脱除HZS的能力相对要低。

【Abstract】 Coal is the most abundant fossil energy in the world. The Integrated Gasification Combined Cycle(IGCC) is considered to be one of the most promising way for high efficiency and clean utilization of coal in the 21th century. The high temperature coal gas desulfurization is regarded as a key technique in the whole IGCC process. Up to now, the one of main problem of high temperature gas desulfurization technology is the regeneration of desulfurization sorbents, which is considered to be a obstacle for industrial development. Cerium oxide sorbent has been studied as a candidate second-generation sorbent for high temperature gas desulfurization. It has been widely noticed in recent years due to the primary advantage of producing element sulfur during the regeneration phase of the process.In this paper, Cerium oxide and Cerium oxide added redmud sorbents were prepared from cereous nitrate and redmud, bentonite was chosen as the additive. An attempt was made to investigate the effects of preparing condition of Cerium oxide on pore volume, strength and desulfurization performance. The Cerium oxide sorbent was subjected reduction/sulffidation experiment in a fixed-bed, simulated Texaco coal-derived was utilized for the experiment; the cerium oxide adding redmud sorbents was subjected sulffidation and regeneration experiment; the fresh and sulfided sorbent having representation were characterized by means of several techniques, such as BET andXRD. It was found that:Cerium oxide sorbents is suitable to removal most of sulfur at high temperature, specially in a strong reducing gas.In the range of 500C to 800C, the BET was rapid enlarge, the pore volume was wide-range increment and the mechanical robustness was augmentation with the heighten of temperature.The activity of desulfurization exhibited pretty well by addition of pore-forming agent in proper quantities, but effects mechanical robustness due to excess.The desulfurization efficiency could be increased by curium oxide reduction, and the longer the time and the higher the temperature became, the higher the desulfurization efficiency reached.The presence of water vapor always inhibited reduction and sulfidation process.The grain size of cerium oxide sorbent had greatly effects on desulfurization performance. The performance of the smaller grain size sorbent was obviously better than the larger grain size ones.Cerium oxide sorbent added redmud improved sulfur capacity and had no primary effects on curium oxide sorbent structure.The regeneration of added redmud sorbent was complete in the temperature of 500C and in the gas having 95% N2 and 5% O2, but had low element sulfur recovery ratio.The reduced valence of cerium oxide sorbents is +3, which combine with Si contained in bentonite and form Ce4.667(SiO4)O. It has low removal H2S ability compared with CeOn(1.5<n<2).

  • 【分类号】X701.2
  • 【被引频次】6
  • 【下载频次】317
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