Xiangyang Liu,Yue Pan,Yichen Huang,Yubin Li,Qianqian Wang,Sha Li,Li Qiu,Ruifeng Li,Xiaoliang Yan
Simultaneous hydrogenation of polycyclic aromatic hydrocarbons and sulfur contaminates (dibenzothiophene, DBT) in coal tar remains a challenge for energy utilization and environmental remediation. Herein, Ni 3 Zn/ZnO–Al 2 O 3 catalysts with different ZnO loading were prepared for deep hydrogenation of phenanthrene (PHE) and synchronous removal of DBT in a fixed-bed reactor. Compared to Ni/Al 2 O 3 , the optimal Ni 3 Zn/ZnO–Al 2 O 3 exhibited superior catalytic performance of 100.0% PHE conversion and 92.5% perhydrophenanthrene selectivity with 100.0% DBT conversion at 300 °C under 6 MPa for 10 h in a fixed-bed reactor. The kinetic study for PHE hydrogenation and mechanism for DBT hydrodesulfurization on Ni catalysts were discussed. Electron transfer from Zn to Ni over the active sites weakened DBT adsorption rather than PHE adsorption. The strong interactions between Ni 3 Zn and ZnO–Al 2 O 3 supports facilitated sulfur migration from the alloy to intimate ZnO, preventing the deactivation of Ni active centers by sulfur deposition and poisoning.
Chong Peng,Peng Liu,Zhiming Zhou,Xiangchen Fang,Yun-Xiang Pan
Phenanthrene hydrogenation is a key reaction for improving the quality of gasoline and diesel. Herein, we conduct detailed thermodynamic and kinetic analyses for phenanthrene hydrogenation on a Ni-Mo/HY catalyst. We establish a comprehensive reaction network for phenanthrene hydrogenation, and calculate equilibrium constant, rate constant, adsorption constant, activation energy barrier, and reaction energy for each step in the reaction network. All of the steps in the reaction network are revealed to be exothermic. A kinetic model with 28 parameters is constructed for phenanthrene hydrogenation. The deviation of the product yields calculated by the kinetic model from those obtained in experiments is less than 4.5%, indicating the reasonability and accuracy of the kinetic model. The most favorable pathway for phenanthrene hydrogenation is demonstrated to be phenanthrene → tetrahydrophenanthrene → sym-octahydrophenanthrene → 5,6-butyl-tetrahydronaphthalene → tetralin. These results are helpful for efficiently tuning catalyst properties and optimizing reaction conditions for enhancing phenanthrene hydrogenation.
Ze-Min Zhao,Yu Zhang,Yu Chen,Jieying Jing,Wen-Ying Li
Nickel–aluminum (Ni–Al) spinel catalysts with distinct Ni/Al molar ratios were synthesized to construct Ni 2+ coordination sites. Owing to the favorable distribution of Ni 2+ coordination sites and the presence of suitable concentration of Ni 2+ in octahedral sites, Ni/Al-0.725 catalyst achieved an 86.1 % average yield of perhydrophenanthrene, which was higher than that obtained with Ni/Al-0.25 (6.3 %). Characterization results indicated that Ni 2+ of the Ni/Al-0.725 catalyst was present in octahedral sites and ∼ 40.4 % Ni 2+ was reduced to Ni, whereas the active Ni metal of Ni/Al-0.25 catalyst mainly comprised Ni 2+ occupying tetrahedral sites as precursors. Furthermore, the Ni/Al-0.725 catalyst exhibited the smallest Ni particle size (2.82 nm) and the largest Ni available surface (19.62 m 2 /g sample ), which helped alleviate competitive adsorption among aromatic hydrocarbons. The Ni reduced by the spinel catalysts was in an electron-deficient state, which enhanced the adsorption of polycyclic aromatic hydrocarbons.
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