摘要
制备了Ni/Al=4.1(原子比)的NiAl类水滑石,焙烧获得NiAl复合氧化物,浸渍K2CO3溶液制备了K改性NiAl复合氧化物催化剂,其中K/Ni=0.05～0.2(原子比),用于N2O催化分解反应。通过元素分析、XRD、BET、H2-TPR、XPS等技术表征了催化剂的组成结构,考察了NiAl类水滑石的预处理方式、K负载量、焙烧温度等制备参数及反应条件对催化剂活性的影响。结果表明,K2CO3溶液浸渍焙烧态NiAl类水滑石(NiAl复合氧化物)制备的催化剂活性高于K2CO3溶液浸渍新鲜类水滑石制备的催化剂,而K/Ni=0.1、400℃焙烧的催化剂活性较高;在NiAl复合氧化物中引入K离子,增大了催化剂表面Ni2+周围的电子云密度,从而减弱了催化剂表面Ni-O键强度,降低了表面NiO的还原温度,提高了催化剂活性。
NiAl mixed oxides derived from hydrotalcite-like compounds（HLCs） with Ni/Al atomic ratio of 4.1 were incipiently impregnated by potassium carbonate solution to prepare K-promoted NiAl mixed oxide catalysts with K/Ni atomic ratio in the range of 0.05 to 0.2,and applied in catalytic decomposition of N2O.The catalysts were characterized by ICP-AES,XRD,BET,H2-TPR,XPS techniques,and their catalytic activities for N2O decomposition were tested.The results show that the catalytic activity of NiAl mixed oxide impregnated by K2CO3 solution is much higher than that of NiAl mixed oxide without K species and superior to the catalyst prepared by fresh NiAl-HLC impregnated using K2CO3 solution.The effect of K loadings and calcination temperatures of catalysts on catalytic activity has been investigated.It is found that the catalytic activity of NiAl mixed oxide,especially the one with K/Ni=0.1 and calcinated at 400 ℃,is largely enhanced by the addition of K species in the presence of oxygen and/or steam.XPS and H2-TPR results show that the electron binding energy of surface active NiO species in K-promoted NiAl mixed oxides shifts to lower value,and the surface Ni-O bond is weakened,thus the reduction peak of surface NiO moves to lower temperature,and the catalytic activity is improved.
出处
《燃料化学学报》
EI
CAS
CSCD
北大核心
2011年第2期115-121,共7页
Journal of Fuel Chemistry and Technology
基金
教育部留学回国人员科研启动基金(2004-527)
中国科学院山西煤炭化学研究所煤转化国家重点实验室开放基金(06-603)
