Quantitative Investigation of MgO Bronsted Basicity: DFT, IR, and Calorimetry Study of Methanol Adsorption
Quantitative Investigation of MgO Bronsted Basicity: DFT, IR, and Calorimetry Study of Methanol Adsorption
复制标题
MgO 布朗斯台德碱度的定量研究：甲醇吸附的 DFT、IR 和量热研究
DOI：
--
复制
发表时间：
2010
期刊：
影响因子：
--
通讯作者：
G. Costentin
中科院分区：
文献类型：
--
作者：
H. Petitjean;K. Tarasov;F. Delbecq;P. Sautet;J. Krafft;P. Bazin;M. Paganini;E. Giamello;M. Che;H. Lauron;G. Costentin
采用周期性密度泛函方法计算了甲醇在MgO缺陷表面的吸附几何构型、能量和振动频率。结果与用水获得的结果非常相似，并且与微量热法和红外实验也非常一致。在低覆盖率下，在涉及低配位离子的所有缺陷上观察到解离。在表面离子的配位数之上，吸附能强烈地受表面拓扑结构的支配：在受限位点上的解离通过桥接两个甚至三个阳离子而产生高度稳定的甲氧基。通过微量热法证实了MgO粉末上这种非常强的位点的发生。的解离能力取决于甲醇的覆盖，因为它修改的表面弛豫和网络的H键，导致，对于一个给定的缺陷，在类似的吸附能的分子和解离的物种在高覆盖率。这就解释了为什么有更强的网站...
The adsorption geometries, energies, and vibrational frequencies of methanol on MgO defective surfaces have been calculated by periodic DFT simulations. The results are very comparable with those obtained with water and are also in very good accordance with microcalorimetry and infrared experiments. At low coverage, the dissociation is observed on all defects involving ions in low coordinations. Over and above the coordination number of surface ions, the adsorption energy is strongly governed by the surface topology: dissociation on confined sites gives rise to methoxy groups highly stabilized by bridging two or even three cations. The occurrence of such very strong sites on MgO powder is confirmed by microcalorimetry. The dissociation ability depends on the methanol coverage because it modifies the surface relaxation and the network of H bonds, resulting, for a given defect, in similar adsorption energies for molecular and dissociated species at high coverage. This explains why there are more strong site...