in the feed with no indication of accelerated fouling in downstream equipment based on pilot unit results the amount of maya resid in the feed could have been raised to at least 50 without downstream plugging once the catalyst was conditioned at a lower concentration of mayan resid also effective in the reduction of transient carbon release is the substitution of regenerated catalyst for new replacement catalyst regenerated used catalyst contains amounts of vanadium as shown in table ix it was found experimentally that regenerated used catalyst with 6 1 vanadium accumulated about 28 wt carbon when first introduced into the bench unit new catalyst initially accumulated about 40 wt carbon it has been found that the amount of carbon on the catalyst decreases as the vanadium content of the catalyst increases other contaminant metals such as nickel iron chromium increase with vanadium table i______________________________________vacuum resid feedstock properties 18 82 50 50 feed amh maya amh maya amh______________________________________gravity api 4 8 u00b0 5 0 u00b0 5 3 u00b0 sulfur wt 5 0 5 0 5 0nitrogen wppm 4480 4770 5290nickel wppm 49 61 80vanadium wppm 166 208 388microcarbon 22 0 22 2 22 0residue1000 u00b0 f sup vol 87 5 84 6 81 1______________________________________ table ii______________________________________operating conditions 18 82 50 50 feed amh maya amh maya.