【作者】 郭婷；

【导师】 米杰；

【作者基本信息】 太原理工大学 ， 化学工艺， 2010， 硕士

【摘要】 近年来,随着经济社会的进步与发展,人们已经意识到环境污染的严重性,环境保护工作成为整个社会的首要任务。煤气应用的发展与普及给日趋成熟的脱硫剂研发产业提出了更高要求,必须解决目前脱硫剂存在的各种不足,开发出工艺适用性强的新型脱硫剂产品。提高脱硫剂性能,首先必须对脱硫剂的脱硫机理、脱硫工艺影响因素进行充分的研究。铁酸锌是目前新一代高温煤气脱硫剂,它同时具备了氧化锌的高脱硫精度和氧化铁的高硫容和反应活性,且具有含阳离子空位的尖晶石结构,更易于H₂S与其反应。氧化铈由于其自身的变价储放氧和良好的分散特性,被视为二代新型脱硫剂应用于煤气脱硫中。本论文主要考察了氧化铈助剂和载体活化半焦的加入对铁酸锌脱硫剂的脱硫效率、硫容和孔结构特性的影响;对复合型脱硫剂进行了硫化和再生性能的研究;通过XRD、BET、XPS和SEM等测试手段,对样品进行了物性表征。由此得出如下结论:1.实验证明,欲使用超声波辅助共沉淀法制备的、添加氧化铈助剂的、炭基铁酸锌脱硫剂是可行的。通过对所得前驱体颗粒进行粒度测试,得出最佳制备条件为:0.5mol/L的Fe（NO₃）₃、Zn（NO₃）₂和Ce（NO₃）₃的混合溶液,在50℃水浴、超声波作用1h,选用氨水进行沉淀反应,之后在烘箱中干燥,在700℃下焙烧2小时。2.脱硫剂活性组分粉末与载体半焦的混合物的焙烧温度和成型脱硫剂前驱体的焙烧温度对铁酸锌、氧化铈晶粒的大小以及脱硫性能有很大影响。前者温度在700℃,后者温度在500℃时,脱硫剂具有较高的脱硫活性。3.助剂在脱硫剂中主要起到造孔、分散活性组分、增大金属氧化物活性和增强机械强度的作用。适当的添加氧化铈,有利于脱硫剂晶粒减小、氧化物分散性增加、延长脱硫剂穿透时间。比较未添加氧化铈的脱硫剂和添加不同质量百分数4.6%、8.2%、11.2%（对应摩尔比4:4:1,4:4:2,4:4:3）氧化铈的脱硫剂,虽然氧化铈本身有助于脱硫活性的提高,但添加氧化铈量不是越多越好,添加量为4.6%的脱硫剂表现出较高的脱硫活性。4.活性半焦具有高的比表面积、发达的微孔结构和良好的低温催化氧化活性等特点,作为载体,可以对活性组分起到一定的分散作用。适当的负载比例,可以有效防止活性组分的烧结,有助于提高脱硫剂的脱硫活性。通过比较8:10、10:10、12:10三种负载比例脱硫剂的硫化性能,认为负载比8:10为最佳比例。5.活性组分是脱硫剂的主要组成部分。活性组分的含量不是越高越好,它与脱硫剂的机械强度有一定的关系,而机械强度则直接关系到脱硫剂的重复使用。本实验选择了四个不同的活性组分含量10%、20%、25%和30%。随着含量的增加,脱硫剂穿透时间和一次硫容都明显增加,但是机械强度却有所下降。综合考虑各物性因素,选择活性组分含量为25%的脱硫剂为重点再生研究对象。6.本实验中由于加入了一定量的氧化铈,以期找到一个在保证铁酸锌硫化活性的基础上能够提高氧化铈转化率的适宜温区或温度。本实验选择320℃-520℃的中高温区考察该脱硫剂活性,结果表明在370℃-470℃范围内,脱硫剂活性较高;之后通过与脱硫精度综合考虑,选择最佳硫化温度为450℃。该复合型脱硫剂可以成功的进行中高温煤气脱硫。7.再生实验部分选择再生条件:再生温度650℃,再生气氛为H₂O-13%,O₂-2%,H₂O/O₂=6.5,其余为N₂补充,空速为2000h^-1。在相同条件下分别对30%、25%、20%的脱硫剂进行再生,其中只有含量为25%的脱硫剂表现出较好的再生性能。8.对活性组分含量为25%的脱硫剂连续进行了三次硫化—再生循环实验,二次硫容比一次硫容增加了2.52%,而第三次硫容则急剧减少,仅为一次硫容的36.87%。三次硫化时间由长到短为:1st>2nd>3rd;三次再生时间由长到短为:2nd>1st>3rd。最后,通过实验过程中的思考与分析,提出对今后该课题研究工作的建议。更多还原

【Abstract】 In recent years, with the development of economic and society, people have realized the seriousness of environmental pollution, thus environmental protection work has been a primary task of the whole society. Application development and popularization of coal gas put forward a higher requirement for desulfurizer industry which is becoming mature, we must address the current various existence shortage of the desulfurizer to develop a new process applicability desulfurizer products.Cerium oxide has been regarded as a new second-generation desulfurizer because of its variable price of oxygen storage and good dispersion characteristics.The purpose of this thesis is try to investigate the effects of the doping of cerium oxide and supports of semi-coke for the desulfurization efficiency, sulfur capacity and pore structure characteristics through the operation of desulfurization and regeneration. And at present time, the next research must be aimed at improving the properties （physical and chemical） of the desulfurizer to enlarge their application limit. Zinc ferrite sorbents are considered to be the novel sorbents, which maintains the high desulfurization efficiency of zinc oxide and the high sulfur capacity and reactivity of iron oxide. The structure of zinc ferrite spinel possesses positive ion-spaces that is favorable to reacting with hydrogen sulfide. Characterization of desulfurizer was carried out by using powder X-ray diffraction, BET methods, X-ray photoelectron spectroscopy and mechanical strength.1. Experiments showed that the desulfurizer which obtained by adding cerium oxide into the carbon-based zinc iron under ultrasonic wave-assisted was feasible. According to the test of particles size of precursor, the optimum preparation conditions were as follows: the concentration of mixed solution of Zn（NO₃）₂,Fe（NO₃）₃, and Ce（NO₃）₃ was 0.5mol/L, the temperature of water bath was 50℃, the time of ultrasonic action was 1h, ammonia was used to precipitation, then dried in the oven, calcined at 700℃for 2 hours.2. The calcination temperature of both active components powder mixed with activated carbon and precursors of desulfurizer had great influence on the grain size of iron zinc, cerium oxide and desulfurization performance. The desulfurizer had the higher desulfurization activity when the former temperature was 700℃, the latter temperature was 500℃.3. Promoter acted as pore-forming, dispersing the active component, increasing the activity of metal oxides and enhance the role of mechanical strength in the desulfurizer. The appropriate addition of cerium oxide would help to reduce the grain size of sorbent, increase the dispersion of oxide, and extend the breakthrough time. Compared with the desulfurizers with different adding amount （0%,4.6%, 8.2%, 11.2%）of cerium oxide, the desulfurizer with 4.6% cerium oxide showed higher desulfurization activity while cerium oxide itself owned desulfurization activity, the large amount of cerium oxide addition was not possible.4. Activated carbon could be used as a carrier for its high surface area and well-developed porous structure. The appropriate mass ratio of activated components to activated carbon could effectively prevent sintering, to improve the desulfurization activity of desulfurizer. Compared with different mass ratio of 8:10, 10:10 and 12:10, the best ratio was 8:10.5. Active component was a major component of sorbent. The content of active component was not as high as possible, it had a certain relationship with mechanical strength which was directly related to the desulfurizer of the re-use. In this study, four content of active component 10%, 20%, 25% and 30% was selected. With the increase of concentration, the breakthrough time and sulfur capacity were significantly increased, but the mechanical strength had declined somewhat. Through the comprehensive consideration, the active component content of 25% was selected for the regeneration of the study focused.6. Due to adding a certain amount of cerium dioxide into the desulfurizer, one purpose of this study is to find out the suitable temperature or temperature zone when the conversion of cerium dioxide could be enhanced on the basis of ensuring the activity of zinc ferrite. In this study, the temperature range of 320℃-520℃was selected to study the activity of desulfurizer, the results show that during the range of 370℃-470℃, the desulfurizers could display the higher activity ; according to the desulfurization accuracy with a comprehensive consideration, the best temperature is 450℃. The compound desulfurizer could be successfully used in medium and high temperature coal gas desulfurization.7. In this study, the selected regeneration conditions are: the temperature is 650℃, the atmosphere is H₂O-13%, O₂-2%, H2O/O2=6.5, N₂ supplement, space velocity is 2000h^-1. Active components of 30%, 25% and 20% of the desulfurizer were regenerated under the same conditions, only the content of 25% showed better regeneration performance.8. For the active component content of 25% of the desulfurizer, three consecutive desulfurization—regeneration recycling experiments were operated, the second sulfur capacity increased 2.52% than the first sulfur capacity, while the third sulfur capacity was drastically reduced, just was 36.87% of the first sulfur capacity. Three times of desulfurization time from long to short was: 1st>2nd>3rd; three regeneration time from long to short was: 2nd>1st> 3rd.Finally, through consideration and analysis in the process of experiments, several points on the subject of future research had been proposed.更多还原