载体对Pd-Fe双金属吸附剂中温煤气脱汞活性及再生性能影响的研究

发布时间：2018-01-18 07:28

本文关键词：载体对Pd-Fe双金属吸附剂中温煤气脱汞活性及再生性能影响的研究　出处：《太原理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：煤气化是现代煤化工的基础,是应用最广泛的洁净煤技术之一,具有效率高,应用广泛等优点。而煤气化过程中的煤气是还原性气氛,比煤燃烧产生的气量小,导致其释放的单质汞远高于燃煤烟气。单质汞具有神经毒性和生物累积性,对人类健康和生态环境具有严重危害;单质汞又具有极高的挥发性、微溶于水和化学性质稳定等特点,与其他形式的汞相比,其最难除去。因此,研发脱汞性能优异的吸附剂显得尤其重要,同时为了使汞脱除剂在工业中能够得到应用,大大的降低商业化运营成本,对汞吸附饱和后的吸附剂进行再生处理,研究具有良好再生性能的脱汞剂具有重要的现实意义。本课题组前期考察了用等体积浸渍法、共沉淀法和溶剂热法制备Pd-Fe双金属吸附剂在中温模拟煤气中的脱汞性能,实验结果证明Pd-Fe双金属吸附剂优异的脱汞活性,同时进一步研究了吸附剂制备条件和脱汞实验条件对吸附剂脱汞活性的影响。本论文在此基础上选择以Beta分子筛、活性炭和γ-Al2O3作为载体,以贵金属Pd和Fe2O3作为脱汞活性组分,用等体积浸渍法和共沉淀法制备Pd-Fe双金属负载型吸附剂,重点考察了三种载体对吸附剂脱汞活性和再生性能的影响以及气氛对吸附剂脱汞活性的影响,并结合XRD、CO脉冲吸附、FTIR、XPS、BET和Hg0-TPD等表征结果,探讨载体对吸附剂的影响。得到如下主要结论:(1)载体对等体积浸渍法制备Pd-Fe双金属吸附剂的脱汞活性具有明显的影响。Pd-Fe/AC吸附剂的脱汞活性最好,脱汞效率在480 min后可以保持在95%左右。其次是Pd-Fe/Beta吸附剂,脱汞效率在480 min后可以保持在90%左右。Pd-Fe/Al2O3吸附剂的脱汞活性最差,脱汞效率在480min内从98%减小到75%。分析结果表明,Pd-Fe/AC吸附剂上活性组分Pd0的表面含量最高,Pd-Fe/Beta次之,Pd-Fe/Al2O3最小,同时Pd在Pd-Fe/AC吸附剂的分散度最好,Pd-Fe/Al2O3最差,从而导致Pd-Fe/AC的脱汞活性最好,Pd-Fe/Al2O3的脱汞活性最差。(2)载体对等体积浸渍法制备Pd-Fe双金属吸附剂再生性能影响较大。其中Pd-Fe/AC的再生性能最好,第一次脱汞效率在400 min内仍保持在95%以上,经过4次再生后,脱汞效率逐渐降低但仍保持在80%左右。其次是Pd-Fe/Beta吸附剂,初次脱汞效率在400 min内保持在90%左右,经过4次再生后,其脱汞效率逐渐降低但仍保持在75%左右。而Pd-Fe/Al2O3吸附剂再生性能最差,经4次再生后,其脱汞效率仅为25%。其原因是在再生实验中,Pd-Fe/Al2O3吸附剂上生成了较多的Pd S,导致活性组分Pd0含量降低,而Pd S在脱附中不能分解产生Pd0,从而Pd-Fe/Al2O3吸附剂的脱汞效率下降快,再生性能较差。(3)共沉淀法制备双金属吸附剂载体对其再生性能的影响较小,且其规律一致。Pd-Fe/AC吸附剂初次脱汞活性在400 min内保持在95%以上,经过4次再生后,其脱汞效率逐渐降低但仍保持在80%左右。Pd-Fe/Beta和Pd-Fe/Al2O3吸附剂的初次脱汞活性在400 min内保持在90%以上,经过4次再生后,其脱汞效率逐渐降低但仍保持在75%左右。(4)煤气中H_2S,H_2和CO对共沉淀法制备Pd-Fe/AC、Pd-Fe/Beta和Pd-Fe/Al2O3吸附剂脱汞活性的影响规律基本一致。H_2S气氛对吸附剂脱汞活性有明显抑制作用,这可能是加入的H_2S与Fe2O3反应生成S0,S0与Pd0反应生成Pd S使活性组分Pd0中毒,从而致使吸附剂的脱汞效率下降。H_2和CO气氛对吸附剂脱汞活性有明显促进作用,这可能是H_2和CO的加入会缓慢还原出活性组分Pd0,从而提高吸附剂的脱汞效率。
[Abstract]:Coal gasification is the foundation of modern coal chemical industry, clean coal technology is one of the most widely used, has the advantages of high efficiency, wide application. But in the coal gasification gas is reducing atmosphere than coal combustion gas is small, resulting in the release of mercury is much higher than that of coal-fired flue gas mercury neurotoxicity has. And bioaccumulation, with serious harm to human health and ecological environment; mercury has a high volatile, slightly soluble in water and the characteristics of chemical stability, compared with other forms of mercury, the most difficult to remove. Therefore, developing excellent adsorbent for mercury removal is particularly important, at the same time in order to make mercury removal agent can be applied in the industry, greatly reduce the cost of commercial operation, carry out regeneration adsorption of mercury after adsorption agent, has important practical significance to study the mercury removal agent has good regeneration performance. Ourprevious study by impregnation method, method and solvothermal synthesis of Pd-Fe double metal adsorbent in temperature simulation of mercury removal characteristic in gas co precipitation. The experimental results show that the Pd-Fe double metal adsorbent for mercury removal activity excellent, and further research the preparation conditions and the mercury removal effect of experimental conditions for mercury removal on the activity of adsorption agent. This paper chooses Beta molecular sieve, activated carbon and gamma -Al2O3 as the carrier, with the noble metal Pd and Fe2O3 as the active component for mercury removal, impregnation method and co precipitation method to prepare Pd-Fe double metal supported adsorbent, emphasis on the three effect of adsorbent carrier on mercury removal activity and regeneration performance and the atmosphere on the adsorbent for mercury removal activity, combined with XRD, CO FTIR, XPS, pulse adsorption, BET and Hg0-TPD characterization results, to explore the influence of carrier on the adsorbent. The main results are summarized as follows. Theory: (1) preparation has obvious effect of mercury removal activity of.Pd-Fe/AC adsorbent for mercury removal activity best Pd-Fe bimetallic sorbent carrier equal volume impregnation method, mercury removal efficiency can be maintained at around 95% in 480 after min. The second is Pd-Fe/Beta adsorbent, mercury removal efficiency at 480 min can be maintained at around 90%.Pd-Fe/Al2O3 adsorbent for mercury removal activity is the worst, the mercury removal efficiency of 480min decreased from 98% to 75%. analysis results show that the surface content of Pd0 Pd-Fe/AC group activity adsorbent was highest, followed by Pd-Fe/Beta, Pd-Fe/Al2O3 and Pd in the Pd-Fe/AC minimum, the best dispersion of absorbing agent, Pd-Fe/Al2O3 is the worst, which lead to Pd-Fe/AC the mercury removal activity is best, Pd-Fe/Al2O3 activity of mercury removal is the worst. (2) preparation of Pd-Fe double metal adsorbent regeneration has great influence on equal volume impregnation method. The carrier regeneration performance of Pd-Fe/AC is the best, the first time the mercury removal efficiency in 4 In 00 min remained at more than 95%, after the 4 regeneration, mercury removal efficiency gradually decreased but remained at around 80%. The second is Pd-Fe/Beta adsorbent, initial mercury removal efficiency in 400 min remained at around 90%, after the 4 regeneration, the mercury removal efficiency gradually decreased but remained at around 75%. While the Pd-Fe/Al2O3 adsorbent regeneration performance is the worst, after 4 times of regeneration, the mercury removal efficiency was only 25%., its reason is in the regeneration experiment, Pd-Fe/Al2O3 adsorbent to generate more Pd S, leading to the active components of Pd0 and Pd decreased, S in high school and can not be decomposed into Pd0, and the removal of mercury Pd-Fe/Al2O3 adsorption efficiency decreased quickly, the regeneration performance is poor. (3) preparation of double metal adsorbent has little effect on the performance of carrier regeneration co precipitation method, and the regularity of.Pd-Fe/AC adsorbent initial mercury removal activity within 400 min remained above 95% after 4 times of regeneration after its removal The efficiency of mercury decreased gradually but still maintain the first.Pd-Fe/Beta at about 80% Pd-Fe/Al2O3 and adsorbent for mercury removal activity within 400 min remained above 90% after 4 times of regeneration, the mercury removal efficiency gradually decreased but remained at around 75%. (4) the gas in H_2S, H_2 and CO on Pd-Fe/AC by co precipitation method for Pd-Fe/Beta and Pd-Fe/Al2O3 adsorbents for mercury removal activity of similar.H_2S atmosphere has obvious inhibitory effects on adsorption of mercury removal activity, which may be H_2S and Fe2O3 reaction of S0 with the reaction of S0 and Pd0 Pd S to generate the active components of Pd0 poisoning, resulting in adsorbents for mercury removal efficiency decreased by.H_2 and CO atmosphere on the adsorbent for mercury removal activity has obvious effect, which may be H_2 and CO will add the slow reduction of the active components of Pd0, so as to improve the efficiency of mercury removal adsorbent.

【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ546.5

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