Abstract: The acidity of zeolite with RTH structure had been studied using the density functional theory generalized gradient approximation(GGA) method for the first time. The Al substitution energy of four different T sites and the deprotonation energies of sixteen different Brnsted acid sites were calculated to found the preferred Al substitution energy and acidic strength of different B acid sites. The results show that T4, locating in the opening (0.56 nm×0.25 nm) of 8-membered ring, is the most favorable T site for Al substitution in the RTH structure. With considerations on both structure and acidity, Al₄-O₉(H)-Si₂ and Al₄-O₁₆(H)-Si₄, locating in the intersection part of the two 8-membered ring channel, show stronger Brnsted acidity and are the most possible active sites for acid catalytic reaction.

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摘要： 采用密度泛函理论中的广义梯度近似方法(GGA)对RTH 结构分子筛的酸性进行了研究。考察了4 个不同T 位的Al 的替代能以及16 个不同Brö nsted 酸位的脱质子能, 从而推断可能的Al 的取代位以及不同酸位的酸性强弱。结果表明, RTH 结构分子筛上最有可能的Al 的取代位为T4 , 位于八元环的孔口(0 .56 nm ×0.25 nm); 从结构和酸性考虑, 易与反应物接触且酸性较强的Brö nsted 酸位点在Al4 -O9(H)-Si2 和Al4 -O16(H)-Si4 上, 并且这两个酸位点都指向两个八元环孔口。

关键词: RTH , 酸性 , 分子筛 , 密度泛函理论