Abstract:

The hydrosulfurization catalyst deactivation by sodium poisoning was studied by element analysis, pore property and acid property characterization and it was confirmed that the significant reduction of acid content was responsible for the poisoning, rather than carbon deposition or impurities blocking the pore. XRD, H₂-TPR and hydrodesulfurization activity characterization confirmed that sodium poisoning strengthened the aggregation of MoO₃, increased the reduction temperature of active metal, and decreased the hydrodesulfurization activity. The catalyst deactivation mechanism was that the macro-molecular sulfides with substituent aromatic rings could not be removed by direct desulfurization, and must be saturated by hydrogenation of the aromatic rings before desulfurization. The reduction of acid content of sodium poisoning catalyst reduced the hydrogenation capacity, resulting in the deactivation of the catalyst. Meanwhile, SEM-EDS analysis confirmed that Na impurities were evenly distributed along the radial direction of the catalyst, and the catalyst had no obvious adsorption to Na impurities. Therefore, even a small amount of Na impurities could penetrate the entire catalyst bed, leading to a significant reduction in the operating run-time of the industrial unit.

Key words: sodium poisoning, hydrodesulfurization (HDS), catalyst, deactivation

摘要：

钠中毒失活加氢脱硫催化剂的元素分析、孔结构和酸性质表征结果证实酸量的显著降低是钠中毒催化剂失活的原因，而非积炭或杂质堵塞孔道。X射线衍射（XRD）、程序升温还原（H₂-TPR）表征和脱硫活性评价结果证实钠中毒强化了MoO₃聚集现象，且活性金属的还原温度随着钠沉积量增加而提高，脱硫活性降低。催化剂失活机理是对于含取代基芳环的大分子硫化物，无法通过直接脱硫途径脱除，必须是先芳环加氢饱和后再脱硫。钠中毒催化剂酸量的下降使其加氢能力降低，催化剂因此失活。扫描电镜能谱（SEM-EDS）分析表征证实Na杂质沿催化剂径向均匀分布，催化剂对Na杂质无明显吸附效果，少量Na杂质即可穿透整个催化剂床层，导致工业装置运行周期显著下降。

关键词: 钠中毒, 加氢脱硫, 催化剂, 失活