A sequential processing for heavy petroleum residues is disclosed which
uses a separate mixture of catalyst and adsorbent. The solid adsorbent and
FCC (fluids catalytic cracking) catalyst particles differ significant at
least on particle size or density or both. The adsorbent preferably
consist of calcined coke or metal oxides of Al, Si, or Mg having enhanced
ability of selectively capture different impurities of the residual oil.
The adsorbent particles first treat the residual hydrocarbons in the riser
bottom end subsequently the actual catalyst tales care of catalytic
cracking in the upper section of the riser. The spent solid mixture is fed
to the catalyst separator which uses steam at sufficiently high velocity
but at lower temperature to lift the catalyst particles out of the
separator. Such a novel low temperature faster separation minimizes
Vanadium mobility and deactivation of the catalyst. A net coke stream is
withdrawn from the separator/burner especially while processing residues
above 5 wt % CCR. This allows successful processing of even very heavy
residues with CCR of 20 wt % and metals (vanadium & nickel) or 300 ppm,
without requiring higher catalyst make up or catalyst and edsorbent
cooling.