改性渣油加氢催化剂硫化期活性相的研究

分别以水蒸气改性和酸碱改性γ-Al₂O₃为载体制备了2种NiMoP/ Al₂O₃渣油加氢催化剂(SR和MG)，并进行不同硫化条件的处理得到硫化态催化剂。构建了原位红外光谱、Raman、XPS、TEM、TG-MS等系统表征体系，全方位研究了硫化态催化剂活性中心的分布、形貌、配位状态以及含碳物种等。结果表明：硫化温度由230℃升高到370 ℃时能促进2种渣油加氢催化剂样品硫化度的提升和NiMoS相的生成，同时含碳物种的含量增加且缩合度增大。与SR催化剂相比，MG催化剂较易硫化，MoS₂条纹较长且层数稍低，NiMoS相占比稍高，说明通过载体改性适当减弱载体与活性相作用，可提高硫化度和活性相助剂化效果，进而提高渣油加氢脱硫率，与反应活性数据一致。通过设计实验证实了硫化过程伴随着积炭前驱体的吸附和生成，高温净化过程中活性相也能发生动态重排、转变和新生。合适的酸中心和活性中心密度、合适的助剂化程度、能够在反应温度下保持活性相的平衡浓度以及积炭前驱体脱附转化能力是理想的渣油加氢催化剂硫化后的特征。

Study on Active Phases of Modified Residue Hydrotreating Catalysts in Sulfurization Stage

Two kinds of residue hydrogenation catalysts (referred as to SR and MG) were prepared by using steam modified and acid-base modified γ-Al₂O₃ materials as support, respectively, and were treated under different curing conditions to obtain the sulfurized catalysts. A series of characterization methods, such as TG-MS, TEM, XPS, Raman and in situ CO-adsorbed FTIR at low temperature, were successfully employed for the sulfurized catalysts of residue hydrotreating, to provide the detailed information on the type of distribution, morphology, chemical states, coordination states of active phases and carbonaceous species at different HDS stages. With the temperature increasing from 230 ℃ to 370 ℃, the degree of sulfurization becomes increased, and the proportion of NiMoS phase gets raised. At the same time, both carbon species content and the degree of condensation are increasing as well. Compared with SR catalyst, MG catalyst is easier to be sulfurized, with longer MoS₂ stripe, lower layers, and higher proportion of NiMoS phase, which indicates that the modification of support appropriately weakens the interaction between support and active phase, improves the degree of sulfurization and promoter effect of catalyst, and then improves the residue hydrodesulfurization rate, which is consistent with the reaction activity data. Results show that sulfurization process is accompanied by the adsorption and formation of carbon precursors, and the active phase is dynamically rearranged, transformed and regenerated. The optimum density of acid sites and active sites, the proper degree of promoter, the ability to maintain the equilibrium concentration of active phase at reaction temperature, and the conversion and desorption ability of coke precursors are the major characteristics of residue hydrotreating catalyst after sulfurization. It provides important support information on vulcanization optimization and initial deactivation control.