The reaction characteristics and mechanism of polymer non-catalytic reduction (PNCR) for NOx removal

Abstract

To overcome the defects of the traditional selective non-catalytic reduction (SNCR) process (e.g., low efficiency, narrow temperature range), a new modified SNCR technology based on the solid complex polymer reducing agents, also called polymer non-catalytic reduction (PNCR), was investigated both in the laboratory and pilot scale to reveal its reaction characteristics and mechanism. The PNCR process demonstrates excellent removal efficiency (about 90%) of NO in furnace in the wide temperature range (850–1150 °C), and possesses promising application feasibility with an average NOx emission concentration of 68.72 mg·m−3 even on unstable industrial operating conditions. The NO removal behaviors influenced by O2, temperature, or water steam illuminate the unique O2-independent and H2O-promoted reaction characteristics of PNCR in the wide temperature range. The thermogravimetric infrared spectra/mass spectrometry (TG-IR/MS) results further reveal a pyrolysis-assisted formation mechanism of active NH2/NH free radicals without the requirement of O2 and high temperature, which avoids the overoxidation of active radicals and accounts for the wide denitrification temperature window, low oxygen compliance and high denitrification efficiency of PNCR process. The excellent NO removal performance as well as the unique reaction characteristics/mechanism of PNCR forebode its broad industrial application prospect in the field of flue gas cleaning.