Effect of modifications on the structure and hydrodenitrogenation activity of Ni Mo SBA 15 catalyst

Abstract

Petroleum refinery is an important industrial process which efficiently produces valuable products from a crude oil. Various processes such as distillation, extraction, reforming, cracking and hydrogenation are used in the refinery. The present investigation deals with the methods to improve the efficiency of Ni-Mo catalyst for hydrodenitrogenation of methylcyclohexylamine. In this view, series of supports viz., mesoporous SBA-15 and SBA-15 modified with Al, F and P at various doping levels were synthesized and used them as support for Ni-Mo catalyst and tested for hydrodenitrogenation activity. Experiments were performed with different liquid sulfiding agents to choose the best sulfiding agent for presulfidation of the catalyst as well to avoid handling gaseous sulfiding agent (H2S). After the careful analysis of sulfur level on the surface of the catalyst and sulfur loss during the reaction, it has been decided to use DMDS or DBPS as sulfiding agent for pre-sulfidation of the catalyst. The study involving the effect of Si/Al ratio and activity of the catalysts indicated that incorporation of aluminium into Si-SBA-15 is beneficial for hydrodenitrogenation activity of NiO-MoO3 catalyst. This study concluded that the high concentration of aluminium is required for maximum hydrodenitrogenation activity of Ni-Mo/Si-SBA-15 catalyst. A direct correlation was made between activity and the amount of aluminium present on the support. Al-SBA-15(10) supported catalyst possesses higher thermal stability than H-AlMCM-41 under the present experimental conditions. This particular catalyst preserved mesoporous nature on prolong reaction time and after 40 runs. The role of additives likes fluorine and phosphorous for the activity of MoO3-NiO supported SBA-15 catalyst was examined at different concentration of fluorine and phosphorous. The results indicated that the addition of fluorine into Si-SBA-15 improved the activity of SBA-15 support. However, addition of phosphorous did not show significant changes in the activity. newline newline