Combined process for upgrading spent alkylation acid and reducing noxious gas content of waste gaseous streams

In the continuous formation of carbon dioxide, nitrogen and concentrated sulfuric acid from industrial flue gas comprising nitrogen oxides, sulfur dioxide, oxygen, and water and spent alkylation acid including hydrocarbons, water and sulfuric acid, the steps that comprise:

• a. contacting said flue gas with a first oxidation catalyst to effect conversion of the nitrogen oxides to nitrogen dioxide and a portion of said sulfur dioxide to sulfur trioxide,
• b. admixing the oxidized flue gas of step (a) with spent alkylation acid to absorb at least a part of the oxides of sulfur and nitrogen resulting in step (a),
• c. treating the unabsorbed gases from step (b) composed of sulfur dioxide and nitrogen oxides with carbon monoxide in the presence of a second oxidation catalyst to yield nitrogen, carbon dioxide and sulfur and separating said nitrogen and carbon dioxide from said sulfur,
• d. burning said alkylation acid containing absorbed flue gases in the presence of oxygen to reduce hydrocarbon and water content thereof to produce a mixture comprising carbon dioxide, nitrogen oxides and sulfur dioxide,
• e. contacting said mixture resulting from step (d) with a third oxidation catalyst in the presence of oxygen to effect conversion therein of said sulfur dioxide to sulfur trioxide,
• f. combining the sulfur trioxide containing mixture resulting from step (e) with a portion of the sulfur trioxides formed in step (i) with water to form sulfuric acid in the aqueous phase,
• g. separating the sulfuric acid formed in step (f) from unabsorbed nitrogen oxides and carbon dioxide gases of step (f), contacting said unabsorbed carbon dioxide and nitrogen oxides with carbon monoxide in the presence of a fourth oxidation catalyst to form carbon dioxide and nitrogen,
• h. adding a portion of the sulfur trioxide formed in step (i) to the separated sulfuric acid of step (g) to effect greater concentration thereof,
• i. oxidizing the sulfur separated in step (c) in the presence of a fifth oxidation catalyst and oxygen to produce sulfur trioxide.