It is generally believed that the presence of sulfur in the feedstock is contributing to HDM reaction, however the nitrogen will inhibit that; experiment proved that sulfur exist in the form of hydrogen sulfide promoting HDM reaction is much larger than that of organic sulfur, in particular the newborn has the greater role which partially offsets the suppressing effect of nitrogen. Thus, catalyst with both desulfurization and demetallization has a higher performance, and can be used in the hydroprocessing of feedstock with high nitrogen.

 

Tungsten trioxide is an important active component of the desulfurization catalyst. We describe a method for preparing heavy oil HDM desulfurization catalyst as following:

1. Select two different forms of aluminum-containing material, aluminum oxide after calcined and aluminum hydroxide dry powder, the aluminum hydroxide dry powder is mixed with the adjuvants or additives containing solution, then get the carrier which the main ingredient is aluminum oxide by molding and activation;

2. The catalyst carrier is carried out an impregnation according to the needed content of active metal components and additives, and then generates the heavy oil HDM desulfurization catalyst containing WO3 by drying and roasting. Wherein the active ingredient are tungsten trioxide (or molybdenum trioxide) and nickel oxide, cobalt oxide, tungsten trioxide takes 0.5%~5.0% of the total mass of the catalyst; additive is alkali metal or alkaline earth metal oxides, such as lithium, sodium, potassium, accounting 0.1~3.0% of the total catalyst mass. Additives and active ingredients can be impregnated simultaneously and also step by step impregnation. Drying and calcining conditions are usually as follows: drying at 100~130 ℃ for 2~6 hours, calcining at 400~650 ℃ for 1~6 hours.

 

The feature of the catalyst prepared in this way is that the additives distributing non-uniformly, expressed as more distributing in the strong acid portion at the surface, and less in the weak acid portion, thus to equilibrium reducing the surface acidity of catalyst.