Three-stage catalyst regeneration

Claim 1

A method for burning nitrogen-containing coke off a coke-containing particulate catalyst, which comprises: (a) separating said coke-containing particulate catalyst into a first portion and a second portion; (b) burning substantially all coke off said first portion of said coke-containing catalyst with a regeneration gas comprising free oxygen in a first regeneration zone, and burning substantially all carbon monoxide formed in said first zone, sufficient free oxygen being introduced into said first zone to provide at least 1 volume percent residual free oxygen in said regeneration gas after burning said coke and carbon monoxide, whereby nitrogen oxides are formed in said first zone; (c) passing said regeneration gas from said first zone into a second zone, forming carbon monoxide and carbon dioxide and generating a substantially oxygen-free atmosphere in said second zone by burning coke off said second portion of said coke-containing catalyst and burning carbon monoxide with substantially all said residual free oxygen, and decreasing the amount of nitrogen oxides in said regeneration gas by reacting at least a portion of said nitrogen oxides in said oxygen-free atmosphere to form free nitrogen; and (d) passing said regeneration gas from said second zone into a third regeneration zone, burning substantially all carbon monoxide generated in said second regeneration zone with additional free oxygen in contact with substantially coke-free catalyst in said third zone.

Claim 2

A method for burning nitrogen-containing coke off a coke-containing particulate catalyst, which comprises: (a) separating said coke-containing particulate catalyst into a first portion and a second portion; (b) burning substantially all coke off said first portion of said coke-containing catalyst with a regeneration gas comprising free oxygen in a first regeneration zone, and burning substantially all carbon monoxide formed in said first zone, sufficient free oxygen being introduced into said first zone to provide at least 1 volume percent residual free oxygen in said regeneration gas after burning said coke and carbon monoxide, whereby nitrogen oxides are formed in said first zone; (c) passing said regeneration gas from said first zone into a second zone, forming carbon monoxide and carbon dioxide and generating a substantially oxygen-free atmosphere in said second zone by burning coke off said second portion of said coke-containing catalyst and burning carbon monoxide with substantially all said residual free oxygen, and decreasing the amount of nitrogen oxides in said regeneration gas by reacting at least a portion of said nitrogen oxides in said oxygen-free atmosphere to form free nitrogen; and (d) passing said regeneration gas from said second zone into a third regeneration zone, burning substantially all carbon monoxide generated in said second regeneration zone with additional free oxygen in contact with substantially coke-free catalyst in said third zone.

Claim 9

A method for burning nitrogen-containing coke off a coke-containing particulate catalyst, which comprises: (a) introducing a major portion of said coke-containing catalyst into a first fluidized bed comprising substantially coke-free catalyst in a lower zone in a vertically extending regeneration vessel; (b) passing a regeneration gas comprising free oxygen upwardly through said lower zone, burning substantially all coke off said major portion of coke-containing catalyst in said first bed, and burning substantially all carbon monoxide formed in said first bed within said lower zone, sufficient free oxygen being introduced into said lower zone to provide at least 1 volume percent residual free oxygen in said regeneration gas at the upper end of said lower zone, whereby nitrogen oxides are generated in said lower zone; (c) introducing a minor portion of said coke-containing catalyst into a second fluidized bed of catalyst in a vertically intermediate zone in said regeneration vessel, passing nitrogen oxides-containing regeneration gas from said lower zone upwardly through said intermediate zone, forming carbon monoxide and carbon dioxide and generating a substantially oxygen-free atmosphere in said second bed by reacting substantially all said residual free oxygen with coke and carbon monoxide in said second bed, and decreasing the amount of nitrogen oxides in said regeneration gas by reacting at least a portion of said nitrogen oxides in said intermediate zone to form free nitrogen; and (d) passing carbon monoxide-containing regeneration gas from said intermediate zone upwardly through a third fluidized bed comprising substantially coke-free catalyst in an upper zone in said regeneration vessel, and burning substantially all carbon monoxide introduced into said upper zone with additional free oxygen in contact with said third bed.

Claim 10

A method for burning nitrogen-containing coke off a coke-containing particulate catalyst, which comprises: (a) introducing a major portion of said coke-containing catalyst into a first fluidized bed comprising substantially coke-free catalyst in a lower zone in a vertically extending regeneration vessel; (b) passing a regeneration gas comprising free oxygen upwardly through said lower zone, burning substantially all coke off said major portion of coke-containing catalyst in said first bed, and burning substantially all carbon monoxide formed in said first bed within said lower zone, sufficient free oxygen being introduced into said lower zone to provide at least 1 volume percent residual free oxygen in said regeneration gas at the upper end of said lower zone, whereby nitrogen oxides are generated in said lower zone; (c) introducing a minor portion of said coke-containing catalyst into a second fluidized bed of catalyst in a vertically intermediate zone in said regeneration vessel, passing nitrogen oxides-containing regeneration gas from said lower zone upwardly through said intermediate zone, forming carbon monoxide and carbon dioxide and generating a substantially oxygen-free atmosphere in said second bed by reacting substantially all said residual free oxygen with coke and carbon monoxide in said second bed, and decreasing the amount of nitrogen oxides in said regeneration gas by reacting at least a portion of said nitrogen oxides in said intermediate zone to form free nitrogen; and (d) passing carbon monoxide-containing regeneration gas from said intermediate zone upwardly through a third fluidized bed comprising substantially coke-free catalyst in an upper zone in said regeneration vessel, and burning substantially all carbon monoxide introduced into said upper zone with additional free oxygen in contact with said third bed.