Rejuvenation of supported group VIII metal catalysts

Claim 1

A method for rejuvenating a catalyst comprising a non-zeolitic Group VIII metal supported on a siliceous zeolite base, said catalyst having been subjected to thermal and/or hydrothermal conditions resulting in a maldistribution of said Group VIII metal on said zeolite base with resultant reduction in hydrogenation activity, which comprises: A. contacting said catalyst in an oxidized or sulfided state and at a temperature below about 300° F with water or water vapor and with ammonia to adsorb therein about 5-40 weight-percent of water containing at least about 5 weight-percent of dissolved ammonia; B. drying and calcining the hydrated-ammoniated catalyst in a non-reducing atmosphere to effect deammoniation thereof, and dehydration to a water content of less than about 25% of its adsorptive capacity for water; C. partially rehydrating the calcined catalyst at a temperature below about 300° F to an extent of not more than about 80% and not less than about 10% of its adsorptive capacity for water; and D. activating the rehydrated catalyst for about 2-40 hours in a stream of essentially dry hydrogen at temperatures gradually increasing to a level between about 600° and 800° F.

Claim 2

A method for rejuvenating a catalyst comprising a non-zeolitic Group VIII metal supported on a siliceous zeolite base, said catalyst having been subjected to thermal and/or hydrothermal conditions resulting in a maldistribution of said Group VIII metal on said zeolite base with resultant reduction in hydrogenation activity, which comprises: A. contacting said catalyst in an oxidized or sulfided state and at a temperature below about 300° F with water or water vapor and with ammonia to adsorb therein about 5-40 weight-percent of water containing at least about 5 weight-percent of dissolved ammonia; B. drying and calcining the hydrated-ammoniated catalyst in a non-reducing atmosphere to effect deammoniation thereof, and dehydration to a water content of less than about 25% of its adsorptive capacity for water; C. partially rehydrating the calcined catalyst at a temperature below about 300° F to an extent of not more than about 80% and not less than about 10% of its adsorptive capacity for water; and D. activating the rehydrated catalyst for about 2-40 hours in a stream of essentially dry hydrogen at temperatures gradually increasing to a level between about 600° and 800° F.

Claim 7

A method for rejuvenating a catalyst comprising a non-zeolitic Group VIII metal supported on a siliceous zeolite base, said catalyst having previously been utilized at elevated temperatures in a hydrocarbon conversion process to substantial deactivation, and having been subsequently regenerated by oxidative combustion to an activity level substantially below that of the original fresh catalyst, which comprises: A. contacting said regenerated catalyst at a temperature below about 300° F with water or water vapor and with ammonia to adsorb therein about 5-40 weight-percent of water containing at least about 5 weight-percent of dissolved ammonia; B. drying and calcining the hydrated-ammoniated catalyst in a non-reducing atmosphere to effect deammoniation thereof, and dehydration to a water content of less than about 25% of its adsorptive capacity for water; C. partially rehydrating the calcined catalyst at a temperature below about 300° F to an extent of not more than about 80% and not less than about 10% of its adsorptive capacity for water; and D. activating the rehydrated catalyst for about 2-40 hours in a stream of essentially dry hydrogen at temperatures gradually increasing to a level between about 600° and 800° F.

Claim 8

A method for rejuvenating a catalyst comprising a non-zeolitic Group VIII metal supported on a siliceous zeolite base, said catalyst having previously been utilized at elevated temperatures in a hydrocarbon conversion process to substantial deactivation, and having been subsequently regenerated by oxidative combustion to an activity level substantially below that of the original fresh catalyst, which comprises: A. contacting said regenerated catalyst at a temperature below about 300° F with water or water vapor and with ammonia to adsorb therein about 5-40 weight-percent of water containing at least about 5 weight-percent of dissolved ammonia; B. drying and calcining the hydrated-ammoniated catalyst in a non-reducing atmosphere to effect deammoniation thereof, and dehydration to a water content of less than about 25% of its adsorptive capacity for water; C. partially rehydrating the calcined catalyst at a temperature below about 300° F to an extent of not more than about 80% and not less than about 10% of its adsorptive capacity for water; and D. activating the rehydrated catalyst for about 2-40 hours in a stream of essentially dry hydrogen at temperatures gradually increasing to a level between about 600° and 800° F.