Acid rain abatement
AssigneeUniversity of Delaware
InventorAlvin B. Stiles
Life of this patent
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Abstract
The process of this invention will remove acid rain precursors, sulfur oxides (SOX) and nitrogen oxides (NOX) by catalytically reducing the NOX to water and elemental nitrogen and the SOX to either H.sub.2 S or elemental sulfur as desired. The process employs specific catalysts in the heteropoly acid or salt group and the spinel or inverse spinel group. The process conditions achieve an oxygen-free environment and reduction is effected with stoichiometric to 100% excess above stoichiometric H.sub.2 or H.sub.2 and CO as reducing gas. Temperatures can be 200.degree. to 900.degree. C. with the lower temperature range being favored space velocity can be 2000 to 20,000 and still achieve 95+% abatement. The only product of the reaction which must be disposed of is saleable elemental sulfur.
Claims25
A method of obtaining acid rain abatement from a flue gas containing nitrogen oxides (NOX) and sulfur oxides (SOX) comprising the steps of treating the flue gas with a reducing agent to remove the remaining oxygen and produce an effluent, the reducing agent being selected from group consisting of natural gas, methane, a mixture of CO and hydrogen derived from steam, hydrocarbon, and hydrogen, passing the effluent over a catalyst to simultaneously reduce the NOX to water and elemental nitrogen and the SOX to H.sub.2 S or elemental sulfur, the catalyst being selected from the group consisting of spinels and inverse spinels, calcined at a temperature no greater than 700.degree. C. and stabilized by a co-precipitated refractory oxide, the refractory oxide being selected from the group consisting of alumina, magnesia, thoria, zirconia, titania, the lanthanides, tin oxide and uranium oxide, the reducing of the NOX and SOX taking place in a temperature range of 200.degree.-900.degree. C., and removing the sulfur or sulfur compounds from the reduced flue gas to thereby remove essentially all of the NOX and SOX.
Dependencies are inferred from the claim text.