摘要
采用高温固相法合成Li1-x Nb1-x W1+x O6(x=0.1,0,-0.1),通过H+交换制备出相应的固体酸H1-x-Nb1-x W1+x O6。采用XRD和FT-IR技术表征固体酸的物相和层板骨架结构,NH3-TPD方法表征其酸性特征。结果表明,3种酸样品的物相相同,但它们的主晶面(002)面间距略有变化。与HNbWO6中的NbO6和WO6八面体结构单元相比,H0.9Nb0.9W1.1O6和H1.1Nb1.1W0.9O6中的NbO6和WO6八面体发生变形。3种酸样品均有两种不同强度的酸位,它们的弱酸位强度基本相等,强酸位强度大小顺序为H1.1Nb1.1W0.9O6>H0.9Nb0.9W1.1O6>HNbWO6,两种酸位的酸量大小顺序均为H1.1Nb1.1W0.9O6>HNbWO6>H0.9Nb0.9W1.1O6。
Layered solid acids H1-xNb1-xW1＋xO6 were prepared by proton exchange of Li1-xNb1-xW1＋xO6（x=0. 1,0,--0. 1）, which were obtained by the high-temperature solid-state method. The phase strueture and lami- nate structure of the as-prepared solid acids were studied by means of powder X-ray diffraetion （XRD） and Fourier transform infrared spectroseopy（FT-IR）. The acid characteristics of the as-prepared sample were characterized with method of ammonia temperature-programmed desorption （NHa-TPD）. The results of XRD indicated that there is the same phase structure and slight difference in the （002） crystal plane spaeing for the three acid samples. And FT-IR analysis state elearly that the NbO6 and WO6 octahedral unit in Ho. 9 Nbo. 9 W1.1 06 and H1.1 Nb1. 1 W0. 9 06 are deformed comparing to HNbWO6. The results of NH3-TPD show that there are two acid sites for each as-prepared sample. For the weak acid sites, their strength is almost equal. However, the acid site strength with higher strong is in order of H1.1Nb1. 1W0. 9 O6 〉 H0. 9 Nb0. 9 W1.1 O6 〉 HNbWO6. The acid amounts of the two acid sites for the three samples are all in order of H1.1 Nbl. 1W0. 9O6〉 HNbWO6 〉 H0. 9 Nb0. 9 W1.1 O6.
出处
《材料导报》
EI
CAS
CSCD
北大核心
2013年第16期67-69,共3页
Materials Reports
基金
安徽省自然科学基金(11040606M38)
关键词
层状化合物
铌钨酸
结构
酸性
layered compound, H1-xNb1-xW1＋xO6, structure, acidic property
