Investigation of the possibility to combine bulk and supported catalysts to increase the efficiency of hydrotreating process

Hydrotreating catalysts are of great interest for researchers in oil refining. Nowadays, bulk NiMoW catalysts attract significant attention due to much higher activity in target hydrotreating reactions. The use of these catalysts as an additional catalyst layer in the main catalyst bed can significantly improve hydrotreating process efficiency, but it is a “know-how” knowledge of the catalyst’s producers. In this work we studied the effects of the order of the bulk and supported catalysts in the bed. The experiments include treating the model feedstocks with DBT or quinoline with the bulk catalyst first and then with the supported catalyst, and vice versa. It was shown that when the bulk catalyst was used first, total HDS and HDN activities of the individual compounds are higher than in the case of the supported catalyst to be first. Hence, using the bulk catalyst first increases total activity of the catalyst bed. In the case of simultaneous presence of sulfur and nitrogen compounds, the greater HDN activity of the bulk catalyst at the first stage facilitates HDS and HDN reactions occurring at the second stage over the supported catalyst. Then, the best catalyst order in bed is the bulk catalyst at the top of the reactor and the supported catalyst at the bottom.