Effect of preparation method of nanosized zeolite HY-Al2O3 composite as NiMo catalyst support on diesel HDS
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摘要: 以纳米HY分子筛-氧化铝混合物为载体，根据两者混合方式的不同（溶胶凝胶法和机械混合法）制备了两种NiMo加氢脱硫催化剂，并对其进行了XRD、BET、TPD、H2-TPR、HRTEM和FT-IR等表征。与溶胶凝胶法催化剂相比，机械混合法催化剂表现出了较好的纹理结构和更高酸量，其金属相更易还原，边角位Mo原子的分散度更高，表现出了更高的加氢脱硫性能。但溶胶凝胶法催化剂的type-Ⅱ Ni-Mo-S活性相前驱物比例更高，MoS2晶片长度更大，堆垛程度更高，活性组分分散度较差。虽然溶胶凝胶法有利于提高type-Ⅱ Ni-Mo-S活性相前驱物比例，但是该方法导致的较差孔结构抑制了这种优势，并且降低了活性组分分散度，减弱了催化活性。Abstract: Two NiMo catalysts using the nanosized zeolite HY-Al2O3 composite (labeled as NYA) prepared by mechanical mixing method and sol-gel method as the support were prepared and characterized by XRD, BET, TPD, H2-TPR, HRTEM and FT-IR spectroscopy. The former catalyst possessed larger pore volume and specific surface area, more acid amount, superior reducibility of metal phase and higher dispersion of edge and corner Mo atoms, and showed higher hydrodesulfurization (HDS) performance. Compared with the former catalyst, the latter catalyst had more MoO3 to be converted to active type-Ⅱ NiMoS phase, possessed higher stacking degree and bigger length of MoS2 slabs, and showed lower active phase dispersion. Although the sol-gel method was beneficial to increase the precursor ratio of type-Ⅱ NiMoS phase, the poor pore structure caused by this method inhibited this advantage and reduced the catalytic activity of the catalyst.
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Key words:
- nanosized zeolite /
- hydrodesulfurization /
- hybrid mode
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Table 1 Textural properties of two catalysts
Sample SBET/
(m2·g-1)Smi/
(m2·g-1)Pore volume
v/(cm3·g-1)Pore size
d/nmCat-S 124.9 15.3 0.27 9.1 Cat-M 207.6 27.6 0.41 9.2 
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Table 2 Amounts of the acid sites of two catalysts
Sample Amount of acid sites/(mmol·g-1 catalyst) B/L (ratio) L B Cat-S 0.32 0.27 0.84 Cat-M 0.53 0.45 0.85
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Table 3 Average stacking degree (NA), average slab length (LA) and fraction available Mo (fMo) of two catalysts
Catalyst NA LA /nm fMo Cat-M 3.1 3.52 0.32 Cat-S 3.6 4.32 0.27
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Table 4 Hydrotreating activity results of FCC diesel over two catalysts
Feedstock Cat-M Cat-S d20 ℃/(g·cm-3) 0.970 0.930 0.935 S concentration, w/(μg·g-1) 7216 652 981 HDS rate/% - 91.7 86.4 Distillation range t/℃ IBP 222 198 201 5% 234 214 219 10% 245 221 226 50% 288 249 255 90% 357 319 306 FBP 380 326 327
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Table 5 S removal rate of DBT, 4-MDBT and 4, 6-DMDBT over different catalysts
Removal rate Cat-M Cat-S DBT/% 99.93 95.47 4-MDBT/% 81.11 76.15 4, 6-DMDBT/% 63.42 61.22
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