Rejuvenation of damaged zeolite-supported metal catalysts

Claim 1

A method for rejuvenating a catalyst comprising about 0.1-3 wt.% of a non-zeolitic Group VIII noble metal supported on a siliceous zeolite carrier having an ion exchange capacity of at least about 0.1 meq/g, and wherein at least about 50% of the original zeolitic metal content of said zeolite carrier has been replaced with hydrogen ions and/or polyvalent metal ions, but which still contains some zeolitic sodium and/or magnesium ions, said catalyst having been previously subjected to thermal and/or hydrothermal conditions resulting in a maldistribution of said Group VIII noble metal on said carrier with resultant reduction in hydrogenation activity and in a deleterious migration of said zeolitic sodium and/or magnesium cations resulting in a reduction in cracking activity, which comprises: (A) contacting said catalyst in an oxidized or sulfided state with a volumetric excess of a reagent consisting essentially of a 0.1-30 weight-percent aqueous ammonium hydroxide solution, and correlating the contacting time with the temperature and reagent strength so as to effect a substantial improvement in hydrogenation activity of said catalyst while retaining therein at least about 90 percent of said Group VIII noble metal; (B) exchanging out a measurable portion of said zeolitic sodium and/or magnesium ions by adding an acid component to said ammonium hydroxide solution while said solution remains in contact with said catalyst, said acid component being added in an amount such that said catalyst is contacted with an extractive proportion of an aqueous ammonium salt solution having a pH below about 8; (C) separating the catalyst from the resulting ammonium salt extract of zeolitic metal cations; and (D) drying and calcining the separated catalyst at temperatures in the range of about 500°-950° F. while maintaining water vapor partial pressures below about 10 psi.

Claim 2

A method for rejuvenating a catalyst comprising about 0.1-3 wt.% of a non-zeolitic Group VIII noble metal supported on a siliceous zeolite carrier having an ion exchange capacity of at least about 0.1 meq/g, and wherein at least about 50% of the original zeolitic metal content of said zeolite carrier has been replaced with hydrogen ions and/or polyvalent metal ions, but which still contains some zeolitic sodium and/or magnesium ions, said catalyst having been previously subjected to thermal and/or hydrothermal conditions resulting in a maldistribution of said Group VIII noble metal on said carrier with resultant reduction in hydrogenation activity and in a deleterious migration of said zeolitic sodium and/or magnesium cations resulting in a reduction in cracking activity, which comprises: (A) contacting said catalyst in an oxidized or sulfided state with a volumetric excess of a reagent consisting essentially of a 0.1-30 weight-percent aqueous ammonium hydroxide solution, and correlating the contacting time with the temperature and reagent strength so as to effect a substantial improvement in hydrogenation activity of said catalyst while retaining therein at least about 90 percent of said Group VIII noble metal; (B) exchanging out a measurable portion of said zeolitic sodium and/or magnesium ions by adding an acid component to said ammonium hydroxide solution while said solution remains in contact with said catalyst, said acid component being added in an amount such that said catalyst is contacted with an extractive proportion of an aqueous ammonium salt solution having a pH below about 8; (C) separating the catalyst from the resulting ammonium salt extract of zeolitic metal cations; and (D) drying and calcining the separated catalyst at temperatures in the range of about 500°-950° F. while maintaining water vapor partial pressures below about 10 psi.

Claim 9

A method for rejuvenating a catalyst comprising about 0.1-3 wt.% of palladium supported on a Y zeolite base having an ion exchange capacity of at least about 0.1 meq/g, and wherein at least about 50% of the original zeolitic metal content of said zeolite carrier has been replaced with hydrogen ions but which still contains some zeolitic sodium ions, said catalyst having previously been utilized in a hydrocarbon conversion process to substantial deactivation and subsequently regenerated by oxidative combustion to remove carbonaceous deposits, and during said hydrocarbon conversion and/or regeneration having been subjected to thermal and/or hydrothermal conditions resulting in a reduction in hydrocarbon conversion activity not recoverable by oxidative combustion of carbonaceous deposits, which comprises: (A) contacting said regenerated catalyst in its oxidized state with a volumetric excess of a reagent consisting essentially of a 0.1-30 weight-percent aqueous ammonium hydroxide solution, and correlating the contacting time with the temperature and reagent strength so as to effect a substantial improvement in hydrogenation activity of said catalyst while retaining therein at least about 90 percent of said palladium; (B) exchanging out a measurable portion of said zeolitic sodium cations by adding an acid component to said ammonium hydroxide solution while said solution remains in contact with said catalyst, said acid component being added in an amount such that said catalyst is contacted with an extractive proportion of an aqueous ammonium salt solution having a pH below about 8; (C) separating the catalyst from the resulting ammonium salt extract of zeolitic sodium cations; and (D) drying and calcining the separated catalyst at temperatures in the range of about 500°-950° F. while maintaining water vapor partial pressures below about 10 psi.

Claim 10

A method for rejuvenating a catalyst comprising about 0.1-3 wt.% of palladium supported on a Y zeolite base having an ion exchange capacity of at least about 0.1 meq/g, and wherein at least about 50% of the original zeolitic metal content of said zeolite carrier has been replaced with hydrogen ions but which still contains some zeolitic sodium ions, said catalyst having previously been utilized in a hydrocarbon conversion process to substantial deactivation and subsequently regenerated by oxidative combustion to remove carbonaceous deposits, and during said hydrocarbon conversion and/or regeneration having been subjected to thermal and/or hydrothermal conditions resulting in a reduction in hydrocarbon conversion activity not recoverable by oxidative combustion of carbonaceous deposits, which comprises: (A) contacting said regenerated catalyst in its oxidized state with a volumetric excess of a reagent consisting essentially of a 0.1-30 weight-percent aqueous ammonium hydroxide solution, and correlating the contacting time with the temperature and reagent strength so as to effect a substantial improvement in hydrogenation activity of said catalyst while retaining therein at least about 90 percent of said palladium; (B) exchanging out a measurable portion of said zeolitic sodium cations by adding an acid component to said ammonium hydroxide solution while said solution remains in contact with said catalyst, said acid component being added in an amount such that said catalyst is contacted with an extractive proportion of an aqueous ammonium salt solution having a pH below about 8; (C) separating the catalyst from the resulting ammonium salt extract of zeolitic sodium cations; and (D) drying and calcining the separated catalyst at temperatures in the range of about 500°-950° F. while maintaining water vapor partial pressures below about 10 psi.