| 摘要 |
This invention relates to an improved catalytic process for carrying out heavy hydrocarbon conversion, usually, but not necessarily, in the presence of nickel and vanadium on the catalyst and in the feedstock, by catalytic cracking gas oils and heavy carbometallic oils to lighter molecular weight fractions. The process is facilitated by the continuous addition of one or more heavy rare earth additives, including gadolinum, terbium, dysprosium, holmium, erbium, and thulium, all having exceptionally high paramagnetic properties, which as they accumulate on aged catalyst, are used to achieve enhanced magnetic separation of aged catalyst. These additives are unusual in that they not only act dramatically as magnetic hooks to assist in removing old, nickel and vanadium poisoned catalyst, but also act to achieve increased activity and improve selectivity of the remaining catalyst, and of equal importance, tend to resist catalyst deactivation. This invention takes advantage of the unusual paramagnetic properties of unpaired sheltered f shell electrons of the heavy rare earths, as well as the enhanced catalytic properties resulting from accumulation of the heavy rare earths on circulating catalyst, and utilizes them as so-called enriching or amplifying "magnetic hooks" to separate more magnetically active, older, less catalytically active and selective, higher metals containing catalyst particulates from less magnetically active, lower metal containing particulates. More importantly, by continuous addition of one or more of these elements, continuous isolation of the more catalytically active and selective catalysts fractions are achieved, enabling them to be recycled back to the unit, thus reducing fresh catalyst addition rates and high costs associates therewith. |
