Abstract: This invention relates to a method of making an olefin from a dialkyl ether comprising (a) introducing an ether having a formula CxH2x+1CyH2y+1 into a thermal or catalytic cracking unit processing a hydrocarbon feedstock; and (b) decomposing at least a portion of the ether to form an olefin having a formula CxH2x and/or CyH2y and an alcohol having a formula CxH2x+1 and/or CyH2y+1OH, wherein x and y independently range from about 1 to about 30. This invention also relates to a method of reducing coking in a thermal or catalytic cracking unit comprising (a) introducing an ether, having a formula CxH2x+1OCyH2y+1, into the cracking unit processing a hydrocarbon feedstock in an amount effective to reduce coke formation relative to processing the hydrocarbon feedstock in the absence of the ether, wherein x and y independently range from about 1 to about 30.

Abstract: Spent FCC catalyst is regenerated under net reducing conditions in a regenerator to minimize the migration of vanadium on the spent FCC catalyst particles. Reducing conditions in at least the bottom 50% of the catalyst bed are maintained by using at least two air distribution grids located in the lower 50% of the catalyst bed.