Ruthenium oxide catalysts for conversion of sulfur dioxide to sulfur trioxide
AssigneeMECS, Inc.
InventorsTimothy R. Felthouse, Abraham Bino
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Abstract
The present invention relates generally to catalysts comprising ruthenium oxide and to processes for catalyzing the oxidation and conversion of sulfur dioxide (SO2) to sulfur trioxide (SO3) using such catalysts. SO2 at low concentrations in process gas streams can be effectively oxidized to SO3 at relatively low temperatures using the ruthenium oxide catalysts of the present invention. In one application, the ruthenium oxide catalysts are used in the final contact stage for conversion of SO2 to SO3 in multiple stage catalytic converters used in sulfuric acid manufacture.
Claims38
A process for the catalytic oxidation of sulfur dioxide to sulfur trioxide, the process comprising contacting a feed gas mixture comprising sulfur dioxide and oxygen with an oxidation catalyst comprising an active phase comprising ruthenium oxide thereby producing a conversion gas comprising sulfur trioxide, wherein the temperature of the gas in contact with the ruthenium oxide oxidation catalyst is no greater than about 400° C.
A process for making sulfuric acid and/or oleum from a source gas comprising sulfur dioxide, the process comprising:
- forming a converter feed gas mixture by combining the source gas with an oxygen source;
- introducing the converter feed gas mixture into a catalytic converter comprising a plurality of catalyst stages in series, each catalyst stage containing an oxidation catalyst effective for oxidizing sulfur dioxide to sulfur trioxide, thereby contacting the converter feed gas mixture with the oxidation catalyst contained in at least the first catalyst stage in said series to form a partial conversion gas comprising sulfur trioxide and residual sulfur dioxide and oxygen;
- passing the partial conversion gas through at least one further catalyst stage in said series, the oxidation catalyst contained therein comprising an active phase comprising ruthenium oxide, thereby oxidizing residual sulfur dioxide in the partial conversion gas to sulfur trioxide and forming a conversion gas comprising sulfur trioxide and residual sulfur dioxide;
- and
- contacting the conversion gas with an aqueous solution comprising sulfuric acid for absorption of sulfur trioxide therefrom in a sulfur trioxide absorption zone to produce additional sulfuric acid and/or oleum and a sulfur trioxide-depleted gas comprising sulfur dioxide.
A process for the preparation of an oxidation catalyst, the process comprising:
- combining a ruthenium salt solution and an acid-resistant support to form a slurry;
- adding a base to the slurry to form a catalyst precursor comprising a ruthenium oxide coating on the surface of the support;
- and
- heat treating the catalyst precursor at a first temperature of from about 200° C. to about 350° C. for from about 0.1 hour to about 5 hours, and at a second temperature from about 50° C. to about 500° C. for from abut 0.1 hour to about 5 hours to convert the catalyst precursor to the oxidation catalyst comprising the support and an active phase thereon comprising ruthenium oxide.
Dependencies are inferred from the claim text.