中文摘要：

用量子化学中的密度泛函理论，在B3LYP／6—31G＋水平上，对二苯并噻吩（DBT）的直接加氢脱硫（DDS）过程进行理论研究。通过对DBT分子在反应过程中的中间体以及过渡态进行量子化学计算，得到各中间产物的能量以及其它参数，从而证明DBT在酸性催化剂上C—S键可自行断裂，完成开环过程。能量差的分析结果表明，C—S键的断裂需要较大的能量，是反应过程中的速率决定步骤，一旦C—S键断裂，在后续的反应过程中硫的脱除相对容易，活泼氢在反应中起到重要作用。

英文摘要：

The direct hydrodesulfurization （DDS） of dibenzothiophene （DBT） is theoretically studied using density functional theory method with 6-31G＊ basis set. The energy and main geometry parameters of the intermediates and transition states of DBT molecules during reaction process are calculated by means of quantum chemistry. Consequently,it is validated that the cleavage of C--S bond in DBT can be happened to achieve ring opening over acidic catalyst. From the results of energy-analysis,it is shown that the cleavage of C--S bond needs high energy,it is the key step,as well as the most difficult step,in the DDS reaction pathway,once it happens sulfur removal in the following steps becomes easy. The active hydrogen atoms existing in the system play an important role in reaction process.