Low pressure cyclic hydrocracking process using multi-catalyst bed reactor for heavy liquids

Claim 1

A catalytic hydrocracking process for direct conversion at low pressure of high-boiling point residua, comprising heteroatoms, metals, sulfur and asphaltenes, to distillate and naphtha, said process comprising cyclic operation of a multi-catalyst bed reactor, containing large-pore catalysts and small-pore catalysts which are Al 2 O 3 impregnated with tungsten and nickel oxides, said large-pore catalysts having a pore size distribution which is characterized by the majority of pores therein being larger than 100 Angstroms in diameter, and said small-pore catalysts having a pore size distribution which is characterized by substantially all pores therein being no more than 80 Angstroms in diameter, wherein said small-pore catalysts have about twice as much NiO and WO 3 as said large-pore ctalysts, have a surface area which is about the surface area of said large-pore catalysts, have a pore volume which is about 70% of the pore volume of said large-pore catalysts, and have an average pore diameter that is about 1/3 of the average pore diameter of said large-pore catalysts, at a pressure of 200-1000 psig, a temperature of 700°-900° F., and a LHSV of 0.1-1-10 by admixing said process-generated distillate, after recycling thereof, with said residua to form solvent-diluted residua and then catalytically hydrocracking, demetalizing, desulfurizing, and decarbonizing said solvent-diluted residua in a single pass-through operation through said reactor in which said large-pore catalysts and said small-pore catalysts are sequentially contacted, said recycled process-generated distillate boiling at about 400°-700° F., so that said operation: (1) converts said high-boiling point residua to low-boiling point hydrocarbons by forming said distillate and said naphtha while removing said heteroatoms, said metals, and carbon residuals from said high-boiling point residua; (2) hydrodesulfurizes said high-boiling point residua; and (3) minimizes metals deposition on said catalysts and blocking of said catalysts pores by said asphaltenes, whereby said catalysts remain usable for runs of commercially acceptable length.