Study Of Hydrodenitrogenation Catalyst For FCC Feedstock

The nitrogen compounds in FCC feedstock are inclined to be adsorbed in the surface acidic center of FCC catalysts which can result in the deactivation of FCC catalysts. In addition, processing huge amount of FCC feedstock with high nitrogen content will cause high nitrogen content in the product gasoline and diesel which does not conform to the increasingly stringent cleaning oil quality requirements. Therefore, the significance of hydropretreatment which is one of the most important technology to reduce the nitrogen content in FCC feedstock become increasingly prominent. On account of that FCC feedstock hydropretreatment technology is the worldwide mature application, the development of catalysts is the key to the development of FCC feedstock hydropretreatment technology.The paper used a variety of methods to modify the pore structure and surface physical and chemical characteristics ofγhe paper in order to make it has larger pore size and volume and proper acidic center which is important to improve the activity of FCC feedstock pretreatment catalyst. BET,XRD,FT-IR,SEM methods etc were employed to characterize and analysis the properties of alumina modified by various of pore enlarging methods and adding boric acid, examining the modification rules of pore structure and surface acidity. The results show that adding 5wt% or 10wt% of 13nm carbon black in the process of preparing alumina can make the alumina carrier have larger average pore size and pore volume. Impregnation of boric acid in alumina can increase its surface Lewis acidity. Finally, the paper prepared a series of catalysts with alumina carrier modified by adding different amount of carbon black and boric acid, using a variety of characterized methods to analysis the properties of them and examining their HDN activity through vacuum gas oil evaluation in reactor. Results show that with the increase of pore size and pore volume, the HDN activity increased slightly; With the increase of boron content in carrier, the number of Br?nsted acid on the surface of catalysts increased and the number of Lewis acid decreased, the crystallinity of MoO₃ and NiMoO₄ increased and so did the agglomeration of metal granular until to the condition of longitudinal agglomeration. With the boron content reached to 3wt%, the HDN activity of catalysts improved slightly, nevertheless, when the boron content reached 5wt%, the HDN activity improved dramatically. The nitrogen conversion of vacuum gas oil reached 77wt%, 15wt% higher to it of catalysts with no boric acid modified.