Reduction of toxic substances, nitrogen oxides, in waste gas emissions

摘要

A process for the removal of pollutants, particularly the reduction or elimination of nitrogen-containing pollutants from gaseous industrial plant effluents. The process involves contacting the waste gas stream with a nitrogen-based reducing agent at a temperature in the range of 150-1300oC, converting part of the nitrogen oxides to nitrogen. Remaining nitrogen oxide in the waste is converted to nitric acid and nitric acid precursors by contacting the waste gas with ozone. The nitric acid and nitric acid precursors are then contacted with an aqueous medium having a pH greater than 7. The aqueous medium converts the nitric acid and precursors to nitrate salt which are then scrubbed from the waste gas. Alternatively the process may involve contacting the waste gas with ozone at a temperature of 25-100oC in an aqueous medium at a pH of at least 9 and with the use of a catalyst, tungsten, palladium, platinum, iridium and rhodium, after the initial ozone contact.