Accurate Adsorption Thermodynamics of Small Alkanes in Zeolites. Ab initio Theory and Experiment for H-Chabazite
Accurate Adsorption Thermodynamics of Small Alkanes in Zeolites. Ab initio Theory and Experiment for H-Chabazite
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DOI：
10.1021/acs.jpcc.5b01739
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发表时间：
2015-03
影响因子：
3.7
通讯作者：
G. Piccini;Maristella Alessio;J. Sauer;Yuchun Zhi;Yuanshuai Liu;R. Kolvenbach;A. Jentys;J. Lercher
中科院分区：
文献类型：
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作者：
G. Piccini;Maristella Alessio;J. Sauer;Yuchun Zhi;Yuanshuai Liu;R. Kolvenbach;A. Jentys;J. Lercher
测量了 H-菱沸石 (Si/Al = 14.4) 中甲烷、乙烷和丙烷的吸附热，并从吸附等温线导出了熵。对于这些系统，已经进行了吉布斯自由能的量子化学从头算。甲烷、乙烷和丙烷的焓和吉布斯自由能与实验值的偏差低于 3 kJ/mol。使用混合高水平（MP2/CBS）：低水平（DFT+色散）方法来确定吸附结构和能量。振动熵和热焓贡献是从 DFT+色散势能面的振动配分函数获得的。已分别评估每种正态模式的非谐波校正。使用内坐标表示来求解一维薛定谔方程，以求出通过正常模式的（曲线）畸变获得的势。
Heats of adsorption of methane, ethane, and propane in H-chabazite (Si/Al = 14.4) have been measured and entropies have been derived from adsorption isotherms. For these systems quantum chemical ab initio calculations of Gibbs free energies have been performed. The deviations from the experimental values for methane, ethane, and propane are below 3 kJ/mol for the enthalpy, and the Gibbs free energy. A hybrid high-level (MP2/CBS): low-level (DFT+dispersion) method is used to determine adsorption structures and energies. Vibrational entropies and thermal enthalpy contributions are obtained from vibrational partition functions for the DFT+dispersion potential energy surface. Anharmonic corrections have been evaluated for each normal mode separately. One-dimensional Schrodinger equations are solved for potentials obtained by (curvilinear) distortions of the normal modes using a representation in internal coordinates.