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首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >IR Study of the Adsorption and Isotopic Scrambling of Thiophene on CaO
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IR Study of the Adsorption and Isotopic Scrambling of Thiophene on CaO

机译：噻吩在CaO上的吸附和同位素加扰的IR研究

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摘要

Thiophene, thiophene-2,5-d_2, and thiophene-d_4 adsorption on CaO activated at 723-973 K has been investigated at 170-300 K by means of IR spectroscopy and IR analysis of desorbed gas. Molecular adsorption of thiophene occurs on surface oxygen ions and basic OH groups by weak H-bonding of CH groups with the lone electron pairs of oxygen. On the most basic oxygen ions of CaO activated at 973 K, thiophene dissociates already at 200 K with the formation of surface OH groups and thiophenide C_4H_3S~- anions. This reversible dissociation accounts for the catalytic reaction of isotopic scrambling of thiophene-2,5-d_2 that takes place already at 220 K and leads to the appearance of all 10 possible thiophene isotopomers in the desorbed gas. Experiments with thiophene coadsorption with CO enable one to associate the sites of thiophene dissociation with those oxygen ions that bound CO giving carbonite CO_2~(2-) ions. Three kinds of such sites could be distinguished, which differ in the band positions of the resulting OH groups and in thermal stability of corresponding thiophenide anions.
机译：通过红外光谱和解吸气​​体的红外分析，研究了噻吩，噻吩-2,5-d_2和噻吩-d_4在723-973 K活化的CaO上的吸附。噻吩的分子吸附发生在表面氧离子和碱性OH基团上，这是由于CH基团与单独的氧电子对之间的弱H键结合所致。在以973 K活化的CaO的最碱性氧离子上，噻吩已经在200 K下解离，形成了表面OH基团和噻吩C_4H_3S〜-阴离子。这种可逆离解解释了噻吩-2,5-d_2同位素加扰的催化反应，该反应已在220 K下发生，并导致在脱附气体中出现所有10种可能的噻吩异构体。噻吩与CO共吸附的实验使人们能够将噻吩解离的位点与那些结合CO的氧离子结合，从而产生亚碳酸盐CO_2〜（2-）离子。可以区分出三种这样的位点，它们在所得的OH基团的能带位置和相应的噻吩阴离子的热稳定性上不同。

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