煤焦油重组分沸腾床加氢处理过程中的结构变化

STUDY ON STRUCTURE CHANGE OF MEDIUM-TEMPERATURE COAL TAR HEAVY FRACTION IN EBULLATED BED HYDROTREATING PROCESS

在沸腾床加氢中型试验装置上开展了中温煤焦油加氢预处理试验,并对中温煤焦油原料沥青和加氢尾油进行了核磁共振氢谱(^(1)H-NMR)测试,考察了中温煤焦油重组分在沸腾床加氢预处理过程中的结构变化。结果表明:与原料沥青相比,加氢尾油平均分子的总碳数和平均侧链长度降低;由于芳香环饱和生成环烷环,加氢尾油的芳环数降低、环烷环数增加;由于部分芳环发生加氢-开环裂化反应和环烷环发生开环反应,加氢尾油平均分子的总环数降低;反应温度越高,上述重组分分子结构变化趋势越明显。在试验温度范围内,加氢尾油的芳环缩合参数(H_(AU)/C_(A))随反应温度的升高呈先增大后减小的趋势,为避免稠环芳烃缩合、减少轻烃生成,应控制煤焦油沸腾床加氢预处理的反应温度不超过(基准+20)℃。

The hydrotreating experiment of medium-temperature coal tar was carried out on the pilot plant of ebullated bed,the hydrogen nuclear magnetic resonance spectroscopy(^(1)H-NMR)of the medium-temperature coal tar feedstock pitch and hydrotreated tail oil were measured,and the structural changes of the medium-temperature coal tar heavy fraction during the ebullated bed hydrotreating process were investigated.The results showed that the total carbon number and the average side chain length of the average molecular structure of the hydrotreated tail oil decreased,the number of aromatic rings decreased and the number of naphthenic rings increased due to the saturation of aromatic rings to naphthenic rings.Because of the partial hydrogenation-ring-opening cracking of aromatic rings and ring-opening of naphthenic rings,the average total number of rings of the hydrotreated tail oil decreased.The higher the reaction temperature was,the more significant the structural change trend of the heavy fraction became.Within the range of experimental temperature,the aromatic ring condensation parameter(H_(AU)/C_(A))of the hydrotreated tail oil increased firstly and then decreased with the increase of reaction temperature.It was suggested that the reaction temperature should be strictly controlled below(base+20℃)in order to avoid macromolecular condensation and reduce the generation of light hydrocarbons.