Catalytic process for removing sulfur dioxide from gas streams

Claim 2

A process for removing sulfur dioxide from a gas stream containing sulfur dioxide comprising passing a gas stream containing sulfur dioxide and a sufficient amount of carbon monoxide and/or hydrogen to reduce at least a portion of said sulfur dioxide to elemental sulfur through a reaction chamber containing a material x La 2 O 3 . y Co 2 O 3 , where x and y are varied independently from 1 to 3, inclusive, to catalytically produce at a sufficiently elevated temperature a product stream comprising elemental sulfur and carbon dioxide or water, and thereafter removing said elemental sulfur from said product stream.

Claim 3

The process of claim 1 wherein said gas stream is heated to a temperature in the range from about 450°C to about 700°C.

Claim 4

The process of claim 1 wherein said material is LaCoO 3 .

Claim 5

The process of claim 1 wherein x ≠ y.

Claim 6

The process of claim 1 wherein said process is characterized by a sulfur dioxide to sulfur conversion efficiency greater than about 90%.

Claim 7

The process of claim 1 wherein said process is characterized by a sulfur dioxide to sulfur conversion efficiency greater than about 90% even after prolonged exposure to substantial proportions of oxygen in said heated gas stream.

Claim 8

The process of claim 1 wherein the production of said product stream proceeds even in the presence of substantial percentages of oxygen in said heated gas stream.

Claim 9

The process of claim 1 wherein not greater than minimal amounts of hydrogen sulfide and carbonyl sulfide are contained in said product stream.

Claim 10

The process of claim 1 wherein said carbon monoxide or hydrogen in said gas stream is in an amount not greater than the stoichiometric amount thereof required for reduction of all oxidants in said gas stream.

Claim 11

The process of claim 1 wherein said carbon monoxide or hydrogen in said gas stream is within ± 15% of the stoichiometric amount required for complete reduction of all oxidants in said gas stream.

Claim 12

The process of claim 1 wherein a portion of said carbon monoxide or hydrogen in said gas stream is generated in situ.

Claim 13

The process of claim 1 wherein a portion of said carbon monoxide or hydrogen in said gas stream is added thereto from an external source.

Claim 14

A process for removing sulfur dioxide from a gas stream containing sulfur dioxide comprising adding carbon monoxide to a gas stream containing sulfur dioxide and oxygen to thereby provide a gaseous reaction stream, the total amount of carbon monoxide in said gaseous reaction mixture being approximately the stoichiometric amount required for reduction of all of said oxygen and said sulfur dioxide in said gaseous reaction stream, heating said gaseous reaction stream to a temperature in the range from about 450°C to about 700°C, passing said heated gaseous reaction stream through at least one reaction chamber containing a material represented by the formula xLa 2 O 3 . yCo 2 O 3 , where x and y are varied independently from 1 to 3, inclusive, to catalytically produce a product stream comprising elemental sulfur, carbon dioxide, and not greater than minimal quantities of hydrogen sulfide and carbonyl sulfide, the sulfur dioxide to sulfur catalytic conversion efficiency being greater than about 90%, and thereafter removing said elemental sulfur from said product stream.

Claim 15

A process for removing sulfur dioxide from a gas stream containing sulfur dioxide comprising adding carbon monoxide to a gas stream containing sulfur dioxide and oxygen to thereby provide a gaseous reaction stream, the total amount of carbon monoxide in said gaseous reaction mixture being approximately the stoichiometric amount required for reduction of all of said oxygen and said sulfur dioxide in said gaseous reaction stream, heating said gaseous reaction stream to a temperature in the range from about 450°C to about 700°C, passing said heated gaseous reaction stream through at least one reaction chamber containing a material represented by the formula xLa 2 O 3 . yCo 2 O 3 , where x and y are varied independently from 1 to 3, inclusive, to catalytically produce a product stream comprising elemental sulfur, carbon dioxide, and not greater than minimal quantities of hydrogen sulfide and carbonyl sulfide, the sulfur dioxide to sulfur catalytic conversion efficiency being greater than about 90%, and thereafter removing said elemental sulfur from said product stream.

Claim 16

The process of claim 13 wherein said material is LaCoO 3 .

Claim 17

The process of claim 13 wherein x ≠ y.

Claim 18

The process of claim 13 wherein said catalytic conversion efficiency is not substantially adversely affected even after prolonged exposure of said catalytic material to said oxygen in said gaseous reaction stream.

Claim 19

The process of claim 13 wherein said carbon monoxide in said gaseous reaction stream is within ± 15% of the stoichiometric amount required for complete reduction of all oxidants in said gaseous reaction stream.

Claim 20

The process of claim 1 wherein said material is supported on a magnesia carrier.

Claim 21

The process of claim 13 wherein said material is supported on a magnesia carrier.

Claim 22

The catalytic material of claim 18 wherein said catalytic material is supported on a magnesia carrier.

Claim 23

The process of claim 1 wherein said material is supported on a zirconia carrier.

Claim 24

The process of claim 13 wherein said material is supported on a zirconia carrier.

Claim 25

The process of claim 1, wherein the elevated temperature is in the range from about 450°C. to about 700°C.