NiO-MgO固溶体用于富氢气体中CO选择甲烷化反应

发布时间：2018-09-19 11:56

【摘要】：质子交换膜燃料电池（PEMFC）稳定发电要求富氢气体中CO含量低于10ppm，然而重整-变换反应后的富氢气体中含有约1%CO和18%CO2。CO选择甲烷化是除去富氢气体中CO的一种有效方法，其能量效率高、过程控制简单，，生成物甲烷和水均对电极以及环境无毒害作用，因此近年来逐渐引起关注。负载镍基催化剂是CO选择甲烷化反应的有效催化剂，而且比贵金属价格低廉。本工作利用NiO与MgO易形成固溶体的特点，首先制备了NiO-MgO固溶体，经还原处理后得到Ni/Mg1-xNixO催化剂，然后对其进行CO选择甲烷化反应活性的研究。主要的研究内容和结果归纳如下： 1、分别采用氢氮混合气（70%H2、30%N2）和反应混合气（70%H2、18CO2、11%N2、1%CO）作为还原气体，对氧化态样品进行还原处理，然后测定其甲烷化反应活性。结果表明，采用氢氮混合气还原得到的催化剂催化活性远高于采用反应气还原得到的催化剂催化活性。 2、采用不同的还原温度（500°C～800°C）对氧化态样品进行还原处理，然后测定其甲烷化反应活性。结果表明，还原温度越高，CO选择甲烷化活性越高，800°C下还原得到的催化剂活性最高。 3、采用不同H2浓度（50%～100%）的氢氮混合气，对氧化态样品进行还原处理，然后测定其甲烷化反应活性。结果表明，当H2浓度为85%时，催化活性最佳；当H2浓度为50%时，催化活性明显降低。 4、对不同Ni/Mg投料比（10%～40%）的氧化态样品，还原后测定其甲烷化反应活性。结果表明，Ni/Mg投料比为20%～30%的催化剂对CO选择甲烷化反应催化效果最好。 5、对不同温度（400°C～800°C）焙烧得到的氧化态样品，还原后测定其甲烷化反应活性。结果表明，随着焙烧温度升高，催化活性降低，特别是800°C焙烧的样品活性降低很明显。
[Abstract]:The stable generation of proton exchange membrane fuel cell (PEMFC) requires that the content of CO in the hydrogen-rich gas is less than 10 ppm. However, the methanation of about 1%CO and 18%CO2.CO in the hydrogen-rich gas after reforming and transformation reaction is an effective method to remove CO from the hydrogen-rich gas. Because of its high energy efficiency, simple process control and no toxic effect of methane and water to the electrode and environment, it has attracted more and more attention in recent years. The supported nickel-based catalyst is an effective catalyst for the methanation of CO and is cheaper than the precious metal. In this work, NiO and MgO are easy to form solid solution. Firstly, NiO-MgO solid solution was prepared. After reduction, Ni/Mg1-xNixO catalyst was obtained, and then the methanation activity of CO was studied. The main research contents and results are summarized as follows: 1. Hydrogen-nitrogen mixture (70H _ 2N _ 2) and reaction gas (n _ 2) (70 H _ 2O _ (18) CO _ (2) C _ (11) N _ (2) CO) were used as reducing gas to deoxidize the oxidized samples, and then their methanation activity was determined. The results showed that the catalytic activity of the catalysts obtained by hydrogen-nitrogen mixture reduction was much higher than that by reaction gas reduction. 2. The oxidized samples were treated with different reduction temperatures (500 掳C ~ 800 掳C). Then the methanation activity was determined. The results show that the higher the reduction temperature is, the higher the methanation activity of CO is, the higher the catalytic activity is at 800 掳C. 3. The hydrogen-nitrogen mixture with different H _ 2 concentration (50 ~ 100%) is used to deoxidize the oxidized samples. Then the methanation activity was determined. The results showed that the catalytic activity was the best when the H _ 2 concentration was 85 and the catalytic activity was significantly decreased when the H _ 2 concentration was 50. 4. The methanation activity of the oxidized samples with different Ni/Mg feed ratio (10 ~ 40%) was determined after reduction. The results show that the catalyst with 20% Ni / mg ratio is the best catalyst for the selective methanation of CO. 5. The methanation activity of oxidized samples calcined at different temperatures (400 掳C, 800 掳C) is determined after reduction. The results show that the catalytic activity decreases with the increase of calcination temperature, especially the activity of the sample calcined at 800 掳C.
【学位授予单位】：北京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O621.25;TM911.4

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