# US 8,784,762 B2 · Treatment of NOx-containing gas streams > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,784,762 B2 - Document ID: US8784762B2 - Status: Granted - Kind: B2 - Application number: 13/027,312 - Filed: 2011-02-15 - Published: 2012-08-16 - Granted: 2014-07-22 - Earliest claimed: 2011-02-15 - Assignees: ATI Properties, Inc. - Applicants: James A. Moore - Inventors: James A. Moore - Web page: https://patentgrep.com/patent/US8784762B2 ## CPC - B01D 53/8631: {Processes characterised by a specific device} - B01D 53/56: Nitrogen oxides (B01D53/60 takes precedence) - C01B 21/40: Preparation by absorption of oxides of nitrogen {(C01B21/26 takes precedence)} - B01D 2251/104: Ozone - C23G 1/02: with acid solutions - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} - C23G: CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS ## Abstract Methods and systems for treating a gas stream comprising NOx are disclosed. In one embodiment of the method, the gas stream comprising NOx is reacted with ozone to form oxidation products including nitrogen sesquioxide and nitrogen pentoxide. At least a portion of the nitrogen sesquioxide and nitrogen pentoxide is reacted with water to form nitric acid, and a solubilized form of the nitric acid is collected and may be reused or otherwise utilized. Systems for conducting the method also are disclosed. ## Claims ### Claim 1 A method of treating a gas stream comprising NOx, the method comprising: generating a gas stream comprising NOx from an acid pickling solution in an acid pickling tank, bath, or spray; contacting the gas stream comprising NOx with ozone in a first chamber, thereby forming oxidation products including nitrogen sesquioxide and nitrogen pentoxide; directly following the preceding step, reacting at least a portion of the nitrogen sesquioxide and nitrogen pentoxide with water in the first chamber, thereby forming nitric acid in the first chamber; collecting at least a portion of the nitric acid in a second chamber in direct fluid communication with the first chamber; and recycling the nitric acid from the second chamber into the acid pickling tank, bath, or spray; wherein the gas stream comprising NOx is not treated with a caustic scrubbing solution in a scrubber between generating the gas stream comprising NOx and recycling the nitric acid. ### Claim 2 (depends on 1) The method of claim 1, wherein the acid pickling solution comprises nitric acid. ### Claim 3 (depends on 1) The method of claim 1, wherein the acid pickling solution has a temperature of at least 140° F. ### Claim 4 (depends on 1) The method of claim 1, wherein generating the gas stream comprising NOx comprises treating one of a metal and an alloy with the acid pickling solution. ### Claim 5 (depends on 4) The method of claim 4, wherein generating the gas stream comprising NOx comprises treating one of stainless steel, titanium, and titanium alloys with the acid pickling solution. ### Claim 6 (depends on 1) The method of claim 1, further comprising mixing the gas stream comprising NOx and the ozone with a mixing device. ### Claim 7 (depends on 6) The method of claim 6, wherein mixing the gas stream comprising NOx and the ozone comprises mixing in a static mixer. ### Claim 8 (depends on 1) The method of claim 1, wherein collecting at least a portion of the nitric acid comprises collecting solubilized nitric acid in a mist eliminator. ### Claim 9 (depends on 8) The method of claim 8, wherein water vapor is introduced into the mist eliminator. ### Claim 10 (depends on 1) The method of claim 1, wherein a flow rate of the gas stream comprising NOx is at least 500 cubic feet/min. ### Claim 11 A method of treating a gas stream comprising NOx, the method comprising: generating a gas stream comprising NOx from a pickling solution; contacting the gas stream comprising NOx with ozone in a first chamber to form oxidation products including nitrogen sesquioxide and nitrogen pentoxide; directly following the preceding step, reacting at least a portion of the nitrogen sesquioxide and nitrogen pentoxide with water to form nitric acid; collecting at least a portion of the nitric acid in a second chamber in direct fluid communication with the first chamber; and recycling the nitric acid from the second chamber into a process or apparatus that generated the gas stream comprising NOx; wherein the gas stream comprising NOx is not treated with a caustic scrubbing solution in a scrubber between generating the gas stream comprising NOx and recycling the nitric acid. ### Claim 12 (depends on 11) The method of claim 11 comprising treating one of a metal and an alloy with a pickling solution comprising the recycled nitric acid. ### Claim 13 (depends on 1) The method of claim 1 comprising introducing the gas stream comprising NOx to the first chamber at a first inlet and introducing the ozone to the first chamber at a second inlet. ### Claim 14 (depends on 13) The method of claim 13, wherein each of the ozone and the gas stream comprising NOx have a flow rate of at least 500 cubic feet/min. ### Claim 15 (depends on 13) The method of claim 13 comprising introducing water to the first chamber at a third inlet.