Vacuum Gasoil Hydrocracking over Three-Layered Packages Consisting of Supported Sulfide NiMo and NiW Catalysts

摘要

A method for vacuum gas oil hydrocracking using a three-layered package of catalysts is proposed, in which the top layer is NiMo/Al_2O_3, the middle is NiM/AAS-Al_2O_3 and the bottom is NiM/Y-Al_2O_3, where M is molybdenum or tungsten, AAS-Al_2O_3 is a support with 70% amorphous aluminosilicate (AAS) and 30% aluminum oxide, and Y is an Al_2O_3 support with 30% zeolite Y and 70% alumina. The acidic properties of the catalysts are studied via the IR spectroscopy of adsorbed CO. The morphology of sulfide particles on a catalyst's surface is studied by means of transmission electron microscopy. Textural characteristics of the supports and catalysts are studied via nitrogen porosimetry. Packages containing NiMo and NiW catalysts in different combinations are tested in the hydrocracking of vacuum gas oil. It is shown that replacing NiMo/AAS-Al_2O_3 with NiW/AAS-Al_2O_3 in a catalyst package containing only NiMo considerably raises the yield of the diesel fraction.