| abstract |
In a hydrocracking process a feed mixture comprising: heavy oil containing asphaltenes and sulfur moieties; an oil-soluble, metal-containing compound additive (such as iron pentacarbonyl or molybdenum 2-ethyl hexanoate), which additive is operative to impede coalescence of coke precursors and which forms hydrocracking catalytic particles in situ; and, optionally, a hydrocarbon diluent which is a solvent for asphaltenes and which will assist with dispersion of the additive; is mixed for a prolonged period at low temperature (e.g., 80 DEG C.-190 DEG C.) in a first vessel or vessels to disperse the additive without significantly decomposing the additive. Preferably, the product mixture is then digested in a second vessel or vessels by mixing it at an elevated temperature (e.g., 250 DEG C.), to decompose the additive. The resulting mixture is then heated to hydrocracking temperature (e.g., 450 DEG C.) and introduced into a reactor. A hydrogen flow, sufficient to maintain mixing in the reactor and efficient (e.g., greater than 98%) stripping of light ends (e.g., end point boiling 20 DEG C.), is provided. the steps of low temperature mixing to achieve dispersion without additive decomposition, preferably digesting to decompose the additive under mixing conditions, and mixing in the reactor with stripping, combine to yield well dispersed, colloidal catalytic particles which function to impede coke evolution and provide high conversion of the high boiling (504 DEG C.) fraction of the feedstock. |