Effect of Organic Additives on the Structure and Hydrotreating Activity of a CoMoS/Multiwalled Carbon Nanotube Catalyst

A comparative study of the effect of citric acid (CA), nitrilotriacetic acid (NTA), and diethylene glycol (DEG) used for the preparation of impregnation solution on the properties and catalytic performance of CoMoS/multiwalled carbon nanotube (MWCNT) hydrotreating catalyst was carried out. For a deeper understanding of the role of organic additives during CoMoS catalyst preparation, thermal analysis, nitrogen physisorption, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy were applied. It was shown that the use of various additives resulted in the formation of CoMoS/MWCNT catalysts with a similar morphology of sulfide particles and similar textural characteristics. However, depending on the type of the additive used, the catalysts exhibited different activities in hydrodesulfurization and hydrodenitrogenation, which changed in the following order: CoMoS-CA > CoMoS-NTA > CoMoS-DEG. CA was found to be the most effective organic additive to the impregnation solution that results in a significant improvement in the activity of the CoMoS catalyst in dibenzothiophene and quinoline conversion as compared to NTA and DEG.