Catalyst for the oxidation of hydrogen sulfide and process for the preparation of the catalyst

Claim 2

A process for the preparation of an oxidation catalyst comprising (i) hydrothermally treating at least a portion of an active alumina support with an aqueous medium, in liquid or vapor phase, comprising an acid, salt, or mixture thereof which dissociates in water to provide a solution having a pH of less than about 9, at a temperature ranging from about 80° C. to about 250° C. for up to 36 hours, and (ii) thence depositing upon said at least partially hydrothermally treated support a catalytically effective amount of a catalytically active oxide phase which comprises the oxides of at least one of the metals, Fe, Cu, Ag, W, Co, Ni, Bi, Cr and Cd, with the provision (iii) that at least one rare earth oxide, alkaline earth metal oxide, zirconium oxide or silica, or any precursor compound thereof, is incorporated into the catalyst during either of the steps (i) or (ii).

Claim 3

The process as defined by claim 1, wherein during the step (i) an active alumina powder having a poorly crystalline and/or amorphous structure is agglomerated into said active alumina support, and said support thus shaped is then hydrothermally treated.

Claim 4

The process as defined by claim 1, wherein during the step (iii) at least one of lanthanum, neodymium, praseodymium or zirconium oxide, or silica, is incorporated into the catalyst.

Claim 5

The process as defined by claim 1, said catalytically active oxide phase comprising from 1 to 15% by weight of the catalyst.

Claim 6

The process as defined by claim 1, said at least one oxide or silica incorporated during the step (iii) comprising from 0.5 to 20% by weight of the catalyst.

Claim 7

The process as defined by claim 1, comprising hydrothermally treating from 10 to 100% of said support.

Claim 8

The process as defined by claim 1, comprising hydrothermally treating from 30 to 100% of said support.

Claim 9

The process as defined by claim 1, wherein said step of depositing upon said at least partially hydrothermally treated support a catalytically active oxide phase comprises the steps of (i) impregnating said support with a solution of a precursor of said catalytically active oxide phase and (ii) calcining the product catalyst at a temperature ranging from 300° to 1000° C.

Claim 10

The process as defined by claim 1, wherein said step of depositing upon said at least partially hydrothermally treated support a catalytically effective amount of a catalytically active oxide phase comprises the steps of (i) mixing said catalytically effective oxides with the alumina while said active alumina support is shaped and (ii) calcining the product catalyst at a temperature ranging from 300° to 1000° C.

Claim 11

The process as defined by claim 8, wherein the precursors of said catalytically active elements comprise at least one of a salt and an acid of said elements.

Claim 12

A process as defined in claim 8, wherein the precursors of catalytically active elements comprise at least one of the nitrates of the elements Fe, Cu, Ag, Co, Ni, and Bi, the halides of Cd and the acids comprising the elements Cr or W.

Claim 13

A process as defined by claim 1, wherein said rare earth oxide, alkaline earth oxide, zirconium oxide or silica, or precursor thereof, is incorporated into said catalyst during step (ii), simultaneously with the process in which the catalytically active oxide phase is deposited upon the at least partially hydrothermally treated alumina support.

Claim 14

A process for the preparation of an oxidation catalyst, comprising the steps of: (i) hydrothermally treating at least a portion of an active alumina powder having a poorly crystalline and/or amorphous structure with an aqueous medium comprising an acid, salt, or mixture thereof, which dissociates in water to provide a solution having a pH of less than about 9, at a temperature ranging from about 80° C. to about 250° C. for up to about 36 hours, (ii) admixing with the hydrothermally treated powder at least one of a untreated active alumina and hydrothermally treated, spheroidal particulates of an active alumina, (iii) shaping the resulting admixture of active alumina powder which is at least partially hydrothermally treated into an active alumina support, and (iv) depositing upon the at least partially hydrothermally treated active alumina support a catalytically effective amount of a catalytically active oxide phase which comprises oxides of at least one of the metals Fe, Cu, Ag, W, Co, Ni, Bi, Cr and Cd, with the proviso (v) that at least one rare earth oxide, alkaline earth metal oxide, zirconium oxide or silica, or any precursor compound thereof, is incorporated into the catalyst during either of the steps (i) or (iv).

Claim 15

A process for the preparation of an oxidation catalyst, comprising the steps of: (i) hydrothermally treating at least a portion of an active alumina powder having a poorly crystalline and/or amorphous structure with an aqueous medium comprising an acid, salt, or mixture thereof, which dissociates in water to provide a solution having a pH of less than about 9, at a temperature ranging from about 80° C. to about 250° C. for up to about 36 hours, (ii) admixing with the hydrothermally treated powder at least one of a untreated active alumina and hydrothermally treated, spheroidal particulates of an active alumina, (iii) shaping the resulting admixture of active alumina powder which is at least partially hydrothermally treated into an active alumina support, and (iv) depositing upon the at least partially hydrothermally treated active alumina support a catalytically effective amount of a catalytically active oxide phase which comprises oxides of at least one of the metals Fe, Cu, Ag, W, Co, Ni, Bi, Cr and Cd, with the proviso (v) that at least one rare earth oxide, alkaline earth metal oxide, zirconium oxide or silica, or any precursor compound thereof, is incorporated into the catalyst during either of the steps (i) or (iv).

Claim 16

A process as defined by claim 13, wherein said catalytically active oxide phase is deposited upon said active alumina support by impregnating said support or the active alumina powder from which it is formed with a solution of at least one precursor compound of oxides of at least one of said metals Fe, Cu, Ag, W, Co, Ni, Bi, Cr and Cd, and thereafter calcining at least one of said alumina support and said alumina powder to form said oxides.

Claim 17

A process as defined by claim 14, wherein said rare earth oxide, alkaline earth metal oxide, zirconium oxide or silica, or precursor thereof, is incorporated into said catalyst during step (iv), simultaneously with the process in which the catalytically active oxide phase is deposited upon the at least partially hydrothermally treated alumina support.

Claim 18

The process as defined by claim 14, said untreated active alumina comprising spheroidal particulates.

Claim 19

The process as defined by claim 14, wherein said admixture is shaped into the active alumina support by extrusion.

Claim 20

The process as defined by claim 14, wherein said admixture is shaped into the active alumina support by oil drop technique.

Claim 21

The process as defined by claim 14, wherein said admixture is shaped into the active alumina support by extrusion.

Claim 22

The process as defined by claim 14, wherein said admixture is shaped into the active alumina support by oil drop technique.

Claim 23

An oxidation catalyst comprising an at least partially hydrothermally treated active alumina support upon which is deposited a catalytically effective amount of a catalytically active oxide phase which comprises the oxides of at least one of the metals, Fe, Cu, Ag, W, Co, Ni, Bi, Cr and Cd, said catalyst also having incorporated therein at least one rare earth oxide, alkaline earth metal oxide, zirconium oxide or silica, said catalyst having a specific surface area of greater than 40 m 2 /g, a bulk density ranging from 0.38 to 0.9 g/cm 3 , and a total pore volume ranging from 1.30 to 0.3 cm 3 /g, wherein the hydrothermal treatment of said portion of the active alumina support comprises contacting said support with an aqueous medium, in liquid or vapor phase, comprising an acid, salt, or mixture thereof which dissociates in water to provide a solution having a pH of less than about 9, at a temperature ranging from about 80° C. to about 250° C. for up to 36 hours.

Claim 24

An oxidation catalyst comprising an at least partially hydrothermally treated active alumina support upon which is deposited a catalytically effective amount of a catalytically active oxide phase which comprises the oxides of at least one of the metals, Fe, Cu, Ag, W, Co, Ni, Bi, Cr and Cd, said catalyst also having incorporated therein at least one rare earth oxide, alkaline earth metal oxide, zirconium oxide or silica, said catalyst having a specific surface area of greater than 40 m 2 /g, a bulk density ranging from 0.38 to 0.9 g/cm 3 , and a total pore volume ranging from 1.30 to 0.3 cm 3 /g, wherein the hydrothermal treatment of said portion of the active alumina support comprises contacting said support with an aqueous medium, in liquid or vapor phase, comprising an acid, salt, or mixture thereof which dissociates in water to provide a solution having a pH of less than about 9, at a temperature ranging from about 80° C. to about 250° C. for up to 36 hours.

Claim 25

The oxidation catalyst as defined by claim 21, said catalytically active oxide phase comprising from 1 to 15% by weight thereof.

Claim 26

The oxidation catalyst as defined by claim 22, said at least one oxide or silica incorporated therein comprising from 0.5 to 20% by weight thereof.