Abstract:

With the deterioration of crude oil supply and the introduction of strict environmental regulations, fluidized bed residue hydrogenation technology has attracted widespread attention. Cylindrical and spherical Ni-Mo/Al₂O₃ catalysts were prepared by the extrusion molding method and the special molding method of STRONG fluidized bed, respectively, and the effect of the catalyst particle morphology on the active phase and residual oil hydrogenation performance was systematically studied. Multiple techniques, including X-ray diffraction (XRD), N₂ adsorption-desorption, H₂ temperature-programmed reduction (H₂-TPR), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and electron microprobe analysis (EMPA), were employed to determine the physico-chemical properties of the catalysts. It was found that spherical catalyst had more active Type Ⅱ MoS₂ phase, excellent textural properties and better fluidization characteristic,which made it exhibited superior hydrogenation activity than that in cylindrical catalyst. The weaker metal-support interaction in spherical catalyst is beneficial for a higher sulfidation degree and the formation of Ni-Mo-S Type Ⅱ active phase with a higher staking degree. Moreover, the spherical catalyst with a larger pore size and pore volume facilitates the diffusion of larger molecular impurities into the pore and adsorption on the catalyst active sites, which results in a uniform distribution of metal deposits in the spherical catalyst rather than concentrated distribution near the pore mouth. Finally, spherical catalyst with a smaller pore size may be easier to be fluidized, enhancing the mass transfer performance of the catalyst. The results provide new ideas for the design and development of more efficient industrial hydrogenation catalyst based on morphology effect.

Key words: catalysis, hydrogenation, alumina, morphology effect, ebullated bed, residue

摘要：

随着原油供应趋于劣质化和严格的环保法规出台，沸腾床渣油加氢技术引起了广泛关注。采用挤压成型法和STRONG沸腾床的特殊成型法分别制备了圆柱形和球形Ni-Mo/Al₂O₃催化剂，系统地研究了催化剂的颗粒形貌对活性相和渣油加氢性能的影响。采用XRD、N₂物理吸脱附、H₂-TPR、HRTEM、XPS和电子微探针分析等手段对催化剂进行了表征。结果表明，球形催化剂具有活性更强的Type Ⅱ类型活性位点、更优异的孔道结构性质和更好的流化性能，这使得其具有更高的渣油加氢活性。球形催化剂中的金属和载体之间相互作用较弱，这有利于形成更高硫化程度和堆垛层数的Ni-Mo-S Ⅱ型活性相，这种活性相在渣油加氢中具有更高的活性。此外，球形催化剂具有比圆柱形催化剂更大的孔径和孔体积，这有利于大分子杂质在孔道中的扩散和活性位点上的吸附，并且使得金属沉积物均匀分布在球形催化剂中，而不是集中分布在孔口。而且球形催化剂尺寸更小，可能更易于流化，这增强了催化剂的传质性能。

关键词: 催化, 加氢, 氧化铝, 形貌效应, 沸腾床, 渣油