（毕业设计论文）《SO2在TiC表面的吸附行为研究》.doc

PAGE SO2在TiC表面的吸附行为研究题 目 二○一二年六月 SO2在TiC表面的吸附行为研究 题 目 二○一二年六月 毕 业 设 计(论文) ` 院 系 机械工程系 专业班级 机械制造专业0801班 学生姓名 指导教师 SO2在TiC表面的吸附行为研究 摘要 本文基于第一性原理的方法，利用CASTEP模块模拟分析了SO2在TiC不同表面的吸附行为。根据TiC的结构特征，分别构建了三种主要的TiC表面（001）、（011）及（111）面，并以此为基础，分析SO2在不同表面的三种吸附方式，即SO2中S与TiC中Ti的吸附，单个O与Ti的吸附及O+O与Ti同时吸附。研究结果表明，TiC各表面对SO2具有较强的吸附能力，其吸附能都为负值，电荷密度计算表明其吸附方式为化学吸附。对不同表面而言，SO2在TiC（001）面的吸附更趋向于Ti（001）+O吸附，其吸附能为--5.883eV，吸附后Ti-O键键长为2.206 ?；在TiC（011）面的吸附更趋向于Ti（011）+2O吸附，其吸附能为-7.471 eV，Ti-O键键长分别为2.132 ?和2.085 ?；而在TiC（111）面的吸附更趋向于Ti（111）+O吸附，其吸附能为-4.419eV，Ti-O键键长为1.944?。综合比较表明，上述三种情况中Ti（011）+2O这种吸附方式，吸附能更小，因此，SO2在TiC表面的吸附更加趋近于该种吸附。 关键词：过渡金属碳化物，催化脱氢，吸附，建模。 STUDY OF THE ADSORPTION OF SO2 ON SURFACE OF TiC Abstract In this dissertation, we using CASTEP module and in first principles method for the foundation to study the adsorption behavior of SO2 on different surfaces of the TiC. According to the structural characteristics of the TiC, three main TiC surface (001), (011) and (111) were constructed and as the basis for analysis the adsorption of SO2 and three possible adsorption manners, which are the adsorption of S on Ti sites, the adsorption of O on Ti sites and the simultaneous adsorption of O and O on Ti sites, are all calculated. Surfaces of TiC have high adsorption capacity of SO2, the adsorp -tion energy is negative, and the charge density calculations show that it is chemical adsorption. On different surfaces, the adsorption of SO2 on TiC(001) surface tends to Ti(001)+O adsorption, it’s adsorption energy is --5.883eV , the key long of Ti-O key after absorption is 2.206 ?;the adsorption on TiC(011) surface tends to Ti(011) +2O adsorption, it’s adsorption energy is -7.471 , the key long of Ti-O keys after absorp -tion are 2.132 ? and 2.085 ?;and the adsorption on TiC(111) surface tends to Ti(111)+O adsorption it’s adsorption energy is -4.419eV , the key long of Ti-O key after absorption is 1.944 ?. Comprehensive comparison showed that the adsorption of SO2 on TiC surfaces tends t