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2h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。
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：nco：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）, N20 （m/e=44）, N2 （m/ e=28） and 02 （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.
出处
《无机化学学报》
SCIE
CAS
CSCD
北大核心
2006年第4期633-638,共6页
Chinese Journal of Inorganic Chemistry
基金
浙江省自然科学基金资助项目(No.Y504131)。
