| Co-Cu-Al水滑石的合成及对NO+CO反应性能的研究 |
| Co-Cu-Al Hydrotalcit: Preparation and Catalytic Activities in NO + CO Reaction |
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| 摘要: 本文研究了Co-Al水滑石中加入过渡金属(M)离子后对NO+CO反应的活性。结果表明Co-Al上引入Cu离子对NO+CO反应具有较高的催化活性；以Co-Cu-Al水滑石为研究对象，考察了Co和Cu含量的变化对NO+CO反应活性的影响，发现Co-Cu-Al对NO+CO反应存在一个最佳Co和Cu的含量配比；当nCo∶nCu∶nAl=5∶3∶1时，其催化活性为最佳，在反应温度120 ℃时，NO的转化率达100%；XRD结果表明Co-Cu-Al经450 ℃焙烧2 h后已有少量的尖晶石相形成，随焙烧温度的提高尖晶石相增多，尖晶石相的形成对催化还原NO有明显的影响；NO-TPD-MS结果表明NO吸附在Co-Cu-Al上的热脱附产物经质谱跟踪能检测到NO(m/e=30)、N2O(m/e=44)、N2(m/e=28)和O2(m/e=32)等4种脱附物种，推测低温脱附物种为吸附在弱位上的NO，而高温脱附物种为吸附在强位上的NO，400 ℃焙烧的Co-Cu-Al水滑石上NO的脱附峰温略低于600 ℃焙烧的，NO在Co-Cu-Al表面的解离是NO+CO反应的速控步骤。 |
| 关键词: Co-Al、Cu-Al和Co-Cu-Al水滑石 尖晶石结构 NO+CO催化反应 |
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| Abstract: The catalytic activities of Co-Al hydrotalcite and the addition of transition metal oxides in NO+CO reaction were examined with a microreactor-gas chromatography (GC) reaction system. Experimental results show that Co-Al with addition of Cu cation is with higher catalytic activity for NO + CO reaction, and the activity of Co-Cu-Al hydrotalcite is affected by the molar ratio of Co∶Cu∶Al. When nCo∶nCu∶nAl was equal to 5∶3∶1, the activity was the highest with 100% NO conversion at reaction temperature of 120 ℃. There were two CuO diffraction peaks at 2θ 35.5° and 38.7° but not a spinel diffraction peaks after Co-Cu-Al (5∶3∶1) was calcined at 350 ℃. But a small amount of spinel was formed after Co-Cu-Al being calcined at 450 ℃ and the amount of spinel increased with calcination temperature, indicating that spinel formation affected NO reduction. As shown in NO-TPD-MS analysis, the thermal desorption products of NO absorbed on Co-Cu-Al are NO (m/e=30), N2O (m/e=44), N2 (m/e=28) and O2 (m/e=32). We suggest that the desorption species of NO occur at the weak positions of Co-Cu-Al in low temperature but at strong positions in high temperature. In addition, the desorption peak temperature of NO on Co-Cu-Al calcined at 400 ℃ is slightly lower than that calcined at 600 ℃, indicating that the dissociation of NO on the surface of Co-Cu-Al is a rate-determining step in NO + CO reaction. |
| Keywords: Co-Al, Cu-Al and Co-Cu-Al hydrotalcite spinel structure NO + CO reaction |
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| 李惠娟,蒋晓原,陈顺林,郑小明.Co-Cu-Al水滑石的合成及对NO+CO反应性能的研究[J].无机化学学报,2006,22(4):633-638. |
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