H-ZSM-5分子筛Brфnsted酸性位吸附NO_x的DFT研究

The DFT Study of NO_x Adsorption on the Brфnsted Acid Sites of the H-ZSM-5 Zeolite

基于量子化学的密度泛函理论(DFT),研究了NOx(NO,N2O)分子在H-ZSM-5分子筛Brфnsted酸性位的吸附。计算采用7T簇模型和B3LYP/6-31G(d,p)方法,得到了H-ZSM-5分子筛孔道中不同B酸位的吸附能和红外光谱。结果表明,NO和N2O分子分别以η1-N模式和η1-O模式吸附于H-ZSM-5分子筛的B酸位。处于分子筛孔道中的B酸吸附NO和N2O的能力不同,H-ZSM-5分子筛直孔道处α位酸吸附能力最强,正弦孔道β位酸次之,吸附能力最弱的是孔道交叉处的γ位酸。

Density functional theory（DFT） was applied to study the adsorption of NOx（NO,N2O） molecules on the Brфnsted acid sites of the H-ZSM-5 zeolite.The calculation was carried out at B3LYP/6-31G（d,p） level based on the 7T cluster model.According to the calculated the infrared spectrum（IR） and the adsorption energies of the different B acid sites,NO and N2O molecules adsorption on the B acid sites in the channel of the H-ZSM-5 zeolite are in the form of the η1-N model and the η1-O model,respectively is proposed.And the adsorption abilities of the B acid sites are different.The highest adsorption ability is α site of the straight channel.The adsorption ability of β site in the sinusoidal channel is secondly.The ability of the γ site is the lowest.