摘要
合成了含Co ,Cu和Ni的M /Mg Al HTL类水滑石 ,并将其焙烧产物用于N2 O催化分解反应 .实验结果表明 ,Co/Mg Al HTL对N2 O分解反应的催化活性明显高于Cu/Mg Al HTL和Ni/Mg Al HTL的活性 .在保持样品中Al含量不变的条件下 ,催化活性随着Co含量的增加及Mg含量的减少而升高 ,各催化剂的活性顺序为 :Co/Al HTL >Co/Mg Al HTL >Cu/Mg Al HTL >Ni/Mg Al HTL .在此基础上 ,进一步考察了Co/Al HTL中Co/Al原子比调变对催化剂活性的影响 .对含Co类水滑石及其焙烧产物进行了XRF ,XRD和N2 O TPD表征 .结果表明 ,含Co类水滑石具有典型的水滑石结构 ,其高温焙烧产物都含尖晶石相 .由于尖晶石相中Co O Al活性中心的作用 ,含Co类水滑石对N2 O分解反应表现出较高的催化活性 .随着Co/Al原子比的增大 ,含Co类水滑石焙烧产物的尖晶石相特征更加突出 ,Co O Al活性中心数目随之增多 ,催化剂的活性也相应升高 .
Some hydrotalcite-like (HTL) compounds, M/Mg-Al-HTL (M=Co,Cu,Ni), were prepared, and their calcination products were applied to the decomposition of N 2O. The decomposition reactivity of N 2O over Co/Mg-Al-HTL is much higher than that over Cu/Mg-Al-HTL or Ni/Mg-Al-HTL. Keeping Al content unchanged, the catalytic activity of Co/Mg-Al-HTL increases with the increase of Co content but decreases with the increase of Mg content. The catalytic activity of these compounds are in the following order: Co/Al-HTL>Co/Mg-Al-HTL>Cu/Mg-Al-HTL>Ni/Mg-Al-HTL. The effect of Co/Al ratio in Co/Mg-Al-HTL on the catalyst activity was studied. The HTL compounds containing Co (Co/Al-HTL and Co/Mg-Al-HTL) and their calcination products were characterized by means of XRF, XRD and N 2O-TPD techniques. The results showed that Co/Al-HTL and Co/Mg-Al-HTL have typical hydrotalcite structure and their calcination products possess spinel phase, the Co-O-Al active centers in the spinel phase are responsible for the high decomposition activity of N 2O. The spinel structure in the calcination product of Co/Al-HTL becomes more apparent when Co/Al ratio increases, therefore the Co-O-Al active centers increase, leading to the increase of the catalyst activity. The active center Co-O-Al can adsorb N 2O very fast and then the adsorbed N 2O can react easily with the oxygen ion of Co-O-Al in spinel to produce O 2 and cause decomposition of N 2O. However, the oxygen ion of M-O is not easy to react with the adsorbed N 2O resulting in that the catalytic activity of the calcined Co/Mg-Al-HTL is lower than that of Co/Al-HTL. The calcined Co/Al-HTL can completely decompose N 2O at 350 ℃, but the calcined Co/Mg-Al-HTL ( n(Co)∶ n(Mg)∶ n(Al)=3∶1∶1)can completely decompose N 2O at 400 ℃. When n(Co)/ n(Al) of Co-Al-HTL is up to 7, the calcined Co-Al-HTL can completely decompose N 2O only at 320 ℃.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2003年第8期595-599,共5页
关键词
钴
铜
镍
类水滑石
尖晶石
一氧化二氮
催化分解
cobalt, copper, nickel, hydrotalcite-like, spinel, nitrogen monoxide, catalytic decomposition
