废润滑油加氢催化剂失活机理研究

Study on the deactivation mechanism of waste lubricating oil hydrogenation catalyst

关键词:  废润滑油  加氢  失活  硅中毒  Ni-Mo催化剂 

Key words:  waste lubricating oil  hydrogenation  deactivation  silicon poisoning  Ni-Mo catalyst

摘要:

目的 研究废润滑油加氢催化剂失活机理。方法 以NiMo/γ-Al₂O₃催化剂为研究对象,对加氢前后的催化剂和油品进行表征分析,从而找出催化剂失活的原因。结果 该催化剂的初始加氢活性很好,对硫(S)、氮(N)及氯(Cl)3种杂元素的脱除率可分别达到83.6%、81.7%和99.7%。但随着反应的进行,从第4周起,催化剂活性下降严重。对反应前后的催化剂进行表征发现,反应后催化剂比表面积和孔容大幅下降,且反应后催化剂成分中硅含量显著增多。结论 造成催化剂活性下降的原因并不是活性金属纳米颗粒的流失,也不是催化剂微观结构的破损,而是随着加氢反应的进行,一方面,油品中的硅加氢后沉积在催化剂表面,致使活性位点被覆盖而无法与反应物接触；另一方面,在固定床管路中堆积的硅限制了传质传热效率,降低了反应活性。 

Abstract:

Objective The aim is to study the deactivation mechanism of waste lubricating oil hydrogenation catalyst. Methods Taking NiMo/γ-Al₂O₃ catalyst as the research object, the catalyst and oil before and after hydrogenation were characterized and analyzed, so as to find out the cause of catalyst deactivation. Results The catalyst showed superior initial hydrogenation activity, and the removal rates of sulfur(S), nitrogen(N) and chlorine (Cl) could reach 83.6%, 81.7%, and 99.7%, respectively. However, with the progress of the reaction, the activity of the catalyst decreased seriously from the 4th week. The characterization of the catalyst before and after the reaction showed that the specific surface area and pore volume of the catalyst decreased significantly after the reaction, and the silicon content in the catalyst composition increased significantly after the reaction. Conclusion sThe reason for the decrease of catalyst activity was neither the loss of active metal nanoparticles, nor the damage of catalysts microstructure, but with the hydrogenation reaction, the silicon in the oil was gradually deposited on the catalyst surface after hydrogenation, resulting in the active site being covered and unable to contact with the reactants. On the other hand, the accumulation of silicon in the fixed bed pipeline limited the mass transfer and heat transfer efficiency, and reduced the reactivity.