MgO对Co-Mo/Al2O3-MgO催化剂性能的影响

摘要

采用尿素螫合剂法制备了不同MgO含量的Co-Mo/Al2O3-MgO催化剂,采用N2吸附-脱附法、TPR、HRTEM等技术对催化剂进行了表征,在管式固定床反应器中以二苯并噻吩(DBT)的二甲苯溶液为模型化合物对催化剂的加氢脱硫活性进行了评价.实验结果表明,添加MgO可显著改善Co-Mo/Al2O3催化剂的结构和性能,Co-Mo/Al2O3-MgO催化剂呈现出多孔径中心的特点；随MgO添加量的增加,Co-Mo/Al2O3-MgO催化剂中的Co.-O-Mo物相增多,硫化后易形成更多高活性Co-Mo-S物相.与Co-Mo/A12O3和Co-Mo/Al2O3-TiO2催化剂相比,Co-Mo/Al2O3-MgO-0.8(载体中MgO的质量分数为0.8)催化剂在氢烃体积比为300时即呈现出很高的DBT脱除率(97.0％),具有低氢烃比下即可实现高加氢脱硫活性的优点.%Co-Mo/Al2O3-MgO catalysts with different MgO content were prepared by urea chelating method and were characterized by means of N2 adsorption-desorption, TPR and HRTEM. The activity of Co-Mo/Al2O3-MgO catalysts in hydrodesulfurization was investigated with xylene solution of dibenzothiophene(DBT) as the model compound in a tubular fixed-bed reactor. The results showed that the addition of MgO evidently changed the structure and performances of the catalysts. Co-Mo/ Al2O3-MgO presented the character of different pore diameter centers. The Co-O-Mo phase in the Co-Mo/Al2O3-MgO catalysts increased with the increase of MgO dosage, which trended to forming more Co-Mo-S phase with high desulfurization activity after sulfurization. DBT removal ratio on the Co-Mo/Al2O3-MgO-0.8(mass fraction of MgO in the support was 0.8) catalyst could reach 97.0% at H2/ hydrocarbon volume ratio 300.