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Alternative TitleStudies on water gas shift reaction suitable for pre-combustion carbon capture technology
Thesis Advisor李春山
Degree Grantor中国科学院研究生院
Degree Discipline化学工艺
Keyword水煤气变换反应   碳化物催化剂   制备
Abstract水煤气变换(WGS)反应是整体煤气化联合循环发电(IGCC)系统的重要组成部分,开发适于燃烧前碳捕集技术的IGCC系统的高效水煤气变换催化剂,对降低系统能耗和操作成本、应对国际碳减排压力具有重要而深远的意义。 本论文研究了适于燃烧前碳捕集工艺的IGCC系统中水煤气变换反应催化剂的制备与优化。开发了四种新型的碳化物催化剂,并对其活性进行了考察,优化后的无载体碳化钼催化剂显示了较好的WGS活性,在此基础上添加了活性组分Fe、Co、Ni、Cu、Zn等过渡金属元素,考察了第二组分的添加对无载体碳化钼催化剂WGS活性的影响。研究表明,Mo2C负载后相比于其他三种碳化物(W2C、FexC和CoxC)显示了较好的活性;无载体单组份碳化钼催化剂的WGS活性在450 °C时达到最高,CO转化率为55.6%,第二组分的添加形成多种物相,反应活性未发生明显改变。 为降低催化剂成本并提高稳定性,对碳化钼催化剂进行了负载,考察了不同催化剂载体(AC,TiO2,CeO2,Al2O3)对WGS催化性能的影响。碳化钼负载后,活性组分为纯净的β-Mo2C相,无其它杂质,在合成过程中实现了前驱体的完全碳化。 对于最优的载体Al2O3负载的碳化钼催化剂,最佳Mo2C的负载量为40 wt.%,并进行了XRD、SEM、TEM、BET等表征,研究了WGS反应活性与催化剂结构特性之间的关系。随活性组分钼负载量的升高,负载型催化剂Mo2C/Al2O3中碳化钼的晶粒逐渐增大,比表面积逐渐减小,WGS活性先升高后降低,分析其主要原因为活性组分碳化钼的负载量增加导致团聚现象。40 wt.% Mo2C/Al2O3催化剂的最佳活性温度为450 °C,此时CO转化率可达60.1%。 对负载型催化剂中活性最好的40 wt.% Mo2C/Al2O3和无载体碳化钼这两种催化剂,进行了86 h长周期稳定性实验,结果表明,Al2O3负载能有效地提高催化剂的寿命,催化剂稳定性得到了较大的改善。综合催化剂制备成本、WGS反应活性以及催化剂的长周期稳定性等,将碳化钼负载到三氧化二铝载体上比直接使用无载体碳化钼催化剂更优。
Other AbstractWater-Gas-Shift (WGS) reaction is a very important part for Integrated Gasification Combined Cycle (IGCC) system. Hence high efficiency WGS catalysts development is the key factor for WGS reaction. In this paper, catalysts for WGS reaction in IGCC system combined with pre-combustion carbon capture technology were prepared and optimized. Four kinds of carbides catalysts (W2C, FexC, CoxC, Mo2C) were prepared and optimized. The activity of WGS was studied. Then the traditional active components such as Fe, Co, Ni, Cu and Zn were added to the catalysts and the influences were investigated. The results suggested that the catalytic activity of bulk molybdenum carbide was higher than that of others. The CO conversion reached the maximum value of 55.6% at 450 °C. The addition of the second component resulted in various phases, and the activity has not exhibited well improvement. To reduce preparation cost and improve stability of the catalyst, further optimization of the supported molybdenum carbides were conducted. The influences of different supporters (AC, TiO2, CeO2, Al2O3) were investigated. It was found that pure β-Mo2C without any other impurities was obtained. The best supporter was found to be Al2O3 and the optimal Mo2C content was 40 wt.%. XRD, SEM, TEM and BET techniques were employed to study the relationship between WGS reactivity and structural properties of the catalysts. The study indicated that with the increasement of the Mo loading, the crystal size of molybdenum carbide enlarged, the specific surface area of the catalysts decreased, while the WGS reactivity increased at first and then decreased. Based on the specific surface area data, the decrease of the catalytic activity was due to the agglomeration of the active component for overloading. For 40 wt.% Mo2C/Al2O3, the CO conversion reached the maximum value of 60.1% at 450 °C. For the optimal supported carbides 40 wt.% Mo2C/Al2O3 and bulk molybdenum carbide, stability tests for a long period of 86 hours were conducted. After the molybdenum carbide was loaded to the alumina supporter, the lifetime and stability of the catalysts were found to be effectively improved. Alumina supported molybdenum carbide catalyst was a better choice than bulk molybdenum carbide, considering the preparation cost, catalytic activity of WGS reaction and long-term stability.
Document Type学位论文
Recommended Citation
GB/T 7714
王木荣. 适于燃烧前碳捕集工艺的水煤气变换反应研究[D]. 中国科学院研究生院,2014.
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