首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Theoretical study of the aluminum distribution effects on the double proton transfer mechanisms upon adsorption of 4,4′-bipyridine on H-ZSM-5
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Theoretical study of the aluminum distribution effects on the double proton transfer mechanisms upon adsorption of 4,4′-bipyridine on H-ZSM-5

机译:H-ZSM-5吸附4,4'-联吡啶对铝分布对双质子转移机理影响的理论研究

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摘要

The aluminum distribution effects on the adsorption of 4,4′- bipyridine (44BPY) in the straight channel of H-ZSM-5 simulated by two ten-membered ring clusters (2-10T) have been investigated by DFT methods. The energetic and structural properties of the complexes formed upon interaction of 44BPY with the zeolite Br?nsted acid sites for six different aluminum distributions were determined by B3LYP/6-31+G* calculations. Dispersion energies were estimated by performing single point calculations at the MP2 and M06-2X levels. Interaction energies were corrected for basis set superposition error (BSSE). The minimum energy pathways of the double proton transfer from H-ZSM-5 to 44BPY were characterized. Two mechanisms are proposed: a concerted mechanism in which both protons are simultaneously transferred giving the bidentate ion pair complex (44BPYH22+/2-10T ~(2-)) and a consecutive mechanism in which one proton is transferred directly leading to the monodentate ion pair complex (44BPYH +/2-10T -), whereas the second proton can be transferred according to Al distribution. The formation of monodentate or bidentate complexes strongly depends on the Al distribution.
机译:通过DFT方法研究了铝分布对H-ZSM-5直通道中4,4'-联吡啶(44BPY)吸附的影响,该直通道由两个十元环簇(2-10T)模拟。通过B3LYP / 6-31 + G *计算确定了44BPY与沸石布朗斯台德酸位点相互作用形成的六种不同铝分布的配合物的能量和结构性质。通过在MP2和M06-2X级别上执行单点计算来估算分散能。校正了相互作用能,以校正基集叠加误差(BSSE)。表征了从H-ZSM-5到44BPY的双质子转移的最小能量途径。提出了两种机理:一种协同机理,其中两个质子同时转移,产生双齿离子对复合物(44BPYH22 + / 2-10T〜(2-));以及一种连续机理,其中一个质子直接转移导致单齿离子对。 (44BPYH + / 2-10T-),而第二个质子可以根据Al分布进行转移。单齿或双齿配合物的形成在很大程度上取决于Al的分布。

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