Synthesis of Ni/NiAlOx Catalysts for Hydrogenation Saturation of Phenanthrene

Dao-Cheng Liu; Yu Chen; Jie-Ying Jing; Antony Rajendran; Hong-Cun Bai; Wen-Ying Li

doi:10.3389/fchem.2021.757908

Synthesis of Ni/NiAlO_x Catalysts for Hydrogenation Saturation of Phenanthrene

Front Chem. 2021 Oct 8:9:757908. doi: 10.3389/fchem.2021.757908. eCollection 2021.

Authors

Dao-Cheng Liu^{1

2}, Yu Chen^{1

2}, Jie-Ying Jing^{1

2}, Antony Rajendran^{1

2}, Hong-Cun Bai³, Wen-Ying Li^{1

2}

Affiliations

¹ State Key Laboratory of Clean and Efficient Coal Utilization, Taiyuan University of Technology, Taiyuan, China.
² Key Laboratory of Coal Science and Technology Ministry of Education, Taiyuan University of Technology, Taiyuan, China.
³ State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering, Ningxia University, Yinchuan, China.

Abstract

The saturation of octahydrophenanthrene was the rate-determining step in the hydrogenation process from phenanthrene to perhydrophenanthrene, which was due to the steric hindrance and competitive adsorption of octahydrophenanthrene. In this work, a series of Ni/NiAlO_x catalysts with a uniform electron-deficient state of Ni derived from the nickel aluminate structure was synthesized to overcome the disadvantage of noble catalyst and the traditional sulfided catalysts in the saturation hydrogenation process of phenanthrene. Results showed that the catalyst calcinated at 650°C possessed more Ni²⁺ (∼98%) occupying octahedral sites and exhibited the highest r_obs (1.53 × 10^-3 mol kg^-1 s^-1) and TOF (14.64 × 10^-3 s^-1) for phenanthrene hydrogenation. Furthermore, its ability to overcome steric hindrance and promote the rate-determining step was proven by octahydrophenanthrene hydrogenation. Comparing the evolution of hydrogenation activity with the change in the electronic structure of surface Ni sites, it was shown that the increase of metallic electron deficiency hindered the π-back bonding between surface Ni and aromatic rings, which was unfavorable for aromatic adsorption. As a result, the phenanthrene hydrogenation saturation performance can be enhanced by stabilizing the electron-deficient state of surface Ni on an optimal degree.

Keywords: calcination temperature; competitive adsorption; metallic electron-deficient state; nickel aluminate; phenanthrene hydrogenation; steric hindrance.