LOW-TEMPERATURE SCR METHOD BASED ON UREA IN THE PRESENCE OF EXHAUST GASES WITH HIGH SULFUR CONTENT Russian patent published in 2020 - IPC B01D53/86 

FIELD: chemical or physical processes.

SUBSTANCE: group of inventions relates to a selective catalytic reduction (SCR) system and methods of reducing emissions of nitrogen oxides in waste gases. System can operate continuously with SCR catalyst at low temperatures (250–350 °C) with waste gas with high content of SO_x (20 ppm or higher) without deactivation due to formation of ammonium bisulphate and/or with improved NO_x removal efficiency at low temperatures. SCR system for continuous urea-based operation includes a source of a solution containing urea and at least one NO₂-forming compound, where at least one compound which forms NO₂ contains: metal nitrate salt; mixture of a compound containing metal nitrate, and N₂O₄, N₂O₅ or mixture thereof; SCR catalyst; and a device for introducing solution from a source of solution into a stream of waste gas, before the exhaust gas comes into contact with the SCR catalyst.

EFFECT: group of inventions provides continuous operation of urea-based SCR system at low temperatures, operation in presence of waste gas with high content of SO_x.

11 cl, 1 ex, 1 tbl, 3 dwg