Molybdenum Carbide and Sulfide Nanoparticles as Selective Hydrotreating Catalysts for FCC Slurry Oil to Remove Olefins and Sulfur.

He Liu,Huihui Pan,Shouhui Jiao,Zhipeng Qiu,Zongxian Wang,Aijun Guo,Feng Wang,Kun Chen

doi:10.3390/nano11102721

Abstract

As the two types of major impurities in FCC slurry oil (SLO), olefins and sulfur seriously deteriorate the preparation and quality of mesophase pitch or needle coke. The development of a hydrotreatment for SLO to remove olefins and sulfur selectively becomes imperative. This work presents the potentiality of dispersed Mo2C and MoS2 nanoparticles as selective hydrotreating catalysts of SLO. Mo2C was synthesized by the carbonization of citric acid, ammonium molybdate and KCl mixtures while MoS2 was prepared from the decomposition of precursors. These catalysts were characterized by XRD, HRTEM, XPS, BJH, BET, and applied to the hydrotreating of an SLO surrogate with defined components and real SLO. The conversion of olefins, dibenzothiophene and anthracene in the surrogate was detected by GC-MS. Elemental analysis, bromine number, diene value, 1H-NMR and spot test were used to characterize the changes of the real SLO. The results show that hydrotreating the SLO surrogate with a very small amount of Mo-based nanoparticles could selectively remove olefins and sulfur without the overhydrogenation of polyaromatics. Mo2C exhibited much better activity than MoS2, with 95% of olefins and dibenzothiophene in the surrogate removed while only 15% anthracene was hydrogenated. The stability of the real SLO was significantly improved. Its structural parameters changed subtly, proving the aromatic macromolecules had been preserved.

Highlights

Slurry oil (SLO) is an important byproduct in the fluidized catalytic cracking (FCC)process
Since SLO is enriched with 3–5 rings of polycyclic aromatic hydrocarbons (PAHs) with short side chains, it is widely known as an excellent potential raw material to produce mesophase pitch and needle coke, which could heighten its utilization value remarkably [2,3,4]
To explore the morphology of the Mo-based nanoparticles, molybdenum carbide (Mo2 C) and MoS2 were prepared according to the steps illustrated in Figure 1 and characterized in detail

Summary

Introduction

Slurry oil (SLO) is an important byproduct in the fluidized catalytic cracking (FCC)process. Due to the ever-increasing supply of heavy oil with the short fall of conventional crudes and persistent high demand for light fuels, the production of SLO rises and its quality inevitably becomes inferior [1]. Since SLO is enriched with 3–5 rings of polycyclic aromatic hydrocarbons (PAHs) with short side chains, it is widely known as an excellent potential raw material to produce mesophase pitch and needle coke, which could heighten its utilization value remarkably [2,3,4]. The olefins are important chemically active intermediates and products in the FCC process. Our group has identified the olefins widely distributed in SLO, and found that they could worsen the thermal stability of SLO, induce a premature coke of SLO thermal processing, and hamper the orderly development of mesophase pitch [7,10]

Methods

Results

Conclusion