负载型纳米TiO_2复合载体及其CoMo催化剂的酸性及孔特性的研究

PHYSICAL FEATURES OF SUPPORTED NANOSIZED TiO_2 COMPOSITES AND CoMo SUPPORTED CATALYSTS

总结了复载不同纳米尺度的复合载体及其CoMo催化剂的表面酸性及孔结构特性的表征结果。结果表明,负载型纳米TiO2与基载体γ Al2O3存在着相互作用。当负载比较少量的纳米TiO2时,复合载体的总酸量随着TiO2含量的增加而增加,超过γ Al2O3的酸量,但当TiO2的含量比较高时复合载体的酸量又降低,纳米TiO2优先负载在γ Al2O3的强酸中心位;负载了CoMo活性组分后酸量增加。不同粒径的纳米TiO2对复合载体和催化剂的酸分布没有明显影响,但对总酸量有影响。对不同尺度TiO2,随着TiO2负载量的增加以及负载金属活性组分的增加,表面积、孔容和最可几孔径均有不同程度的减少。

The physical features of nanosized combined support and CoMo supported catalysts with different nanosized scales were summarized. NH_3-TPD was used to determine the acidic features of nanosized TiO_2/Al_2O_3 composites and CoMo supported catalysts. The results showed that the supported nanosized TiO_2 and the matrix γ-Al_2O_3 interacted with each other. When a small quantity of TiO_2 was carried on the matrix, the total amount of acid sites increased with TiO_2 content, and the composites had larger acid amount than matrix. The CoMo catalysts had much larger acid amount. From the shape of the TPD traces of the composites, we reached the conclusion that nanosized TiO_2 is prior to support on the strong acid sites of the matrix. The crystalline size of TiO_2 had more influence on acid amount than on acid distribution. The novel CoMo supported catalysts possesse suitable aperture properties and high hydrogenation activity for oil refining.