【摘要】 利用一个3T簇模型模拟分子筛催化剂的酸性位,采用密度泛函理论(DFT)的B3LYP/6-31G(d,p)方法,研究了分子筛催化1-丁烯双键异构为trans-2-丁烯的反应机理.对反应各驻点进行了全优化,经过零点能校正后,得到了反应的活化能.研究表明,反应分三步进行:物理吸附→化学反应→物理脱附.分子筛的酸性位OH基团首先吸附1-丁烯的双键形成了π配位复合物,然后按协同反应机理发生双键异构反应,生成吸附态的trans-2-丁烯,最后脱附成产物.计算得到的表观活化能为57.1kJ·mol-1,与实验结果接近.更多还原

【Abstract】 Using density functional theory(DFT), the double-bond isomerization of 1-butene to trans-2-butene overzeolites is investigated with a 3T cluster model simulating zeolite. At the B3LYP/6-31G(d, p) level, the completegeometry optimization and the activation energy calculation are performed with a EZP correction. It is found thatthe process include three steps, physical adsorption→chemical reaction→physical desorption. Firstly, the OHgroup of the acidic site of zeolite adsorbs the double-bond of 1-butene and forms a π-complex. Secondly, thedouble-bond isomerization reaction shows a concerted mechanism and yields the adsorbed trans-2-butene. Lastly,trans-2-butene is produced by desorption and the zeolite active site is restored. The calculated apparent activationenergy is 57.1 kJ·mol-1, which is in agreement with the experimental data.更多还原