Residue additives bottoms cracking

When residual fractions boiling above 450°C are cracked on a high-activity matrix, the matrix is quickly deactivated by the high levels of metal impurity and Coruadson earbom A bottom-ciaeking additive can be added to reduce eoke deposition when using a high proportion of residue in the feed. If neeessary, a vanadium metal trap can also be included. 

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