An experiment and simulation study of the effect of using liquid additives on the selective non-catalytic reduction (SNCR) process is presented, providing a novel way for plants reducing NO
X
emissions. An experimental study is conducted in an entrained flow reactor, and CHEMKIN is applied for simulation study. Ethanol additive can effectively shift the temperature window of the NO
X
OUT process to a lower range and the NO
X
OUT efficiency ranges from 29 to 56% at 700–800°C. Furthermore, ethanol additive has a significant inhibitory effect on ammonia slip. Na
2
SO
4
and C
2
H
5
OH can be combined into a compound additive, which has a synergistic effect on NO reduction. The addition of methanol can greatly promote denitrification efficiency from 650°C to 725°C, indicating the potential of compound additives in NO reduction. The HNCO + OH = H
2
O + NCO pathway is also proven to be enhanced for ethanol decomposition, thereby providing OH•, which is active in NO reduction. Finally, the reaction routes for ethanol on the urea-based SNCR process at the proper temperature are proposed.
NO reduction by hydrocarbons and oxygenated compounds in O2 excess over a Pt/Al2O3 catalyst
