摘要
恒定二价与三价阳离子比为3((nZn+nMg)/nAl=3),采用共沉淀法制备不同Zn含量的系列类水滑石前驱物ZnxMg3-xAl-HT(x=0,0.5,1.0,1.5,2.0,2.5,3.0),经焙烧得到其衍生复合氧化物催化剂ZnxMg3-xAlO,用于N2O的直接催化分解.采用X射线衍射(XRD)、比表面积分析(Brunauer-Emmett-Teller)、热分析(TG-DSC)和傅里叶变换红外(FT-IR)光谱等表征手段考察了Zn含量对材料前驱物及其衍生复合氧化物组成和结构的影响,研究了系列ZnxMg3-xAlO催化剂的N2O催化分解性能,同时探讨了反应条件,如N2O浓度、空速、O2和H2O等因素对催化剂活性的影响.结果表明,所有前驱物材料均能形成完整的层状水滑石结构;经高温焙烧后形成了以Zn-Al尖晶石为主相的复合氧化物,且Zn掺杂有助于促进尖晶石相的生成;Zn含量对材料的热稳定性、比表面积和N2O催化分解活性有显著的影响;随着Zn含量增加,催化剂比表面积下降,但其不是影响催化剂活性的主要因素;650℃焙烧后的Zn2.0Mg1.0AlO催化剂具有较好的N2O催化分解活性;N2O浓度、空速及O2对催化剂活性的影响较小,而H2O则对活性有较大的影响.
A series of hydrotalcite-like precursors with different Zn contents of ZnxMg3-xAl-HT （x=0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0） were synthesized by co-precipitation methods, and by keeping the atomic ratio of M^2＋/M^3＋ constant at 3. Mixed oxides derived from these precursors through calcination were applied to N2O catalytic decomposition. X-ray diffraction （XRD）, BET surface area, thermal analysis （TG-DSC）, and Fourier transform infrared （PT-IR） techniques were used to study the influence of Zn content on the composition and structure of precursors and corresponding mixed oxides. N2O catalytic decomposition behavior over ZrxMg3-xAlO catalysts was investigated and impacts of reaction conditions, such as N2O concentration, space velocity,O2 and H2O on catalytic activity, were studied in detail. The results showed that the complete hydrotalcite layer structure was formed in all precursors. After calcination the main catalyst phase is Zn-Al spinel. The introduction of Zn promotes the formation of the spinel. Mg can improve the thermal stability of catalysts to some degree. Zn content has an important influence on the thermal stability, surface area and activity of the catalyst. As Zn content increases the surface area of the catalyst decreases. Surface area is, however, not an important factor in N2O catalytic decomposition. Zn2.0Mg1.0AlO catalyst, calcined at 650 ℃, shows relatively good activity for N2O decomposition. The N2O concentration, space velocity, and O2 have little impact on activity, while H2O obviously influences the activity of N2O catalytic decomposition.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2009年第2期353-359,共7页
Acta Physico-Chimica Sinica
基金
国家863课题(2008AA06Z305)
北京市教委科技发展计划(KM200710017006)资助
关键词
氧化亚氮
类水滑石
复合氧化物
催化分解
催化活性
N2O
Hydrotalcite-like component
Mixed oxide
Catalytic decomposition
Catalytic activity
作者简介
Corresponding author. Email： hexuwen@sina.com.cn; Tel： ＋8610-62331025.
