State Key Laboratory of Clean and Efficient Coal Utilization,Taiyuan University of Technology

Abstract:Coal tar is rich in dense cyclic aromatic hydrocarbons phenanthrene, and perhydrophenanthrene is an ide⁃al component for high energy density fuels used in aerospace because of its high energy, high density and high stabili⁃ty. The key is to design efficient hydrogenation catalysts. Noble metal catalysts have the characteristics of high hydro⁃genation capacity, but have the disadvantage of high cost. Traditional nickel⁃molybdenum⁃sulfur catalysts haveweak hydrogenation capacity, and nickel based catalysts are widely used in the aromatics hydrogenation saturationfield due to their low price and high hydrogenation saturation capacity. The Ni/ NiAlOx catalysts are used by the stronginteraction between the active nickel metal and the support nickel aluminum spinel, which makes the active compo⁃nent nickel show the “ electron deficient” state and promote the adsorption and activation of aromatics. This catalyst has high perhydrophenanthrene selectivity, but perhydrophenanthrene selectivity decreases gradually as the re⁃action proceeding, mainly due to the change of nickel’s electron density during the reaction. Considering that co⁃balt has a similar structure to nickel, it is easy to dissolve into the nickel lattice and directly modulate nickel's elec⁃tronic structure. The catalysts with different cobalt contents were prepared by the sol⁃gel method followed by impregna⁃tion method, and then the effect of cobalt doping on the structure and the performance of Ni/ NiAlOx catalysts withphenanthrene hydrosaturation was investigated. The catalysts were evaluated at a reaction temperature of 300 ℃, pres⁃sure of 5.0 MPa, reaction feed: 1% phenanthrene/ decahydronaphthalene solvent, feed rate: 6 mL/ h, hydrogen flowrate: 60 mL/ min, and weight hourly space velocity: 52 h-1. The catalyst with cobalt doping of 2% had a perhydro⁃phenanthrene selectivity of 53.6% at the 6th of the reaction, which was higher than that of the Ni/ NiAlOx catalyst.This is due to the fact that the appropriate content of cobalt doping promotes the reduction of active metal,reduces the catalyst particle size, stabilizes the “electron deficiency” of the active component Ni, promotes the ad⁃sorption of aromatics, and finally improves the catalyst stability.