Hydrodesulfurization and hydrodenitrogenation processes

Catalysts based on MoSi are used to remove sulfur and nitrogen from organic molecules in hydrodesulfurization and hydrodenitrogenation processes. 

In general, it can be concluded, that although a large scale biphasic solution process for hydrodesulfurization and hydrodenitrogenation is not likely to come soon, there are promising results in homogeneous catalysis which can lead to constmction of such processes in the future. 

On the other hand, zeolite-based catalysts have not developed any significant interest in other important processes such as catalytic reforming, hydrogenation of olefins and aromatics, hydrodesulfurization and hydrodenitrogenation. This lack of utility is attributable, in part, to the high cracking activity exhibited by active zeolite-based catalysts. 

Tungsten alloyed with nickel, cobalt, or rhodium in thin layers on alumina supports, also sulfided, is used on an industrial scale as a catalyst in crude oil processing (hydrotreating, hydrocracking, reforming, hydrodesulfurization, and hydrodenitrogenation), as well as in Fischer-Tropsch synthesis (alcohol formation from CO + H2). 

In a number of petrochemical processes, a gas (hydrogen) is present as reactant. In hydrodesulfurization (HDS), hydrocracking (HC), and hydrodenitrogenation (HDN), the reaction products H2S and ammonia, respectively, are known to decrease the catalyst activity, but are partly transferred to the gas phase. Therefore, also these processes profit from reactive stripping. 

Transition metal complexes containing coordinated small molecules such as CO, 02, and N2 have been known for many decades and are of critical importance in industrial and biological processes and coordination chemistry as a whole (Table 1.1). Of all the industrially relevant molecules, H2 is arguably the most important. Catalytic hydrogenation reactions represent the most massive man-made chemical reactions in the world All crude oil is treated with hydrogen to remove sulfur and nitrogen in hydrodesulfurization/hydrodenitrogenation processes. Ten billion tons of ammonia is produced worldwide by the Haber process ... 

S-compounds, N-compounds and M (Metal) compounds have different reactivities and chemistry depending on the boiling ranges of fractions in which they are found. Thus, specific processes have been developed for the removal of each of these impurities. These are classified as hydrodesulfurization (HDS), hydrodenitrogenation (HDN) and hydrodemetallation (HDM) processes, respectively. These are in turn subdivided into processes, which are optimized for the boiling range of the particular feedstock being treated. 

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