Evolution of S/N surface functional group of zhungeer lignite/char during rapid combustion

Abstract

Surface characteristics of Chinese lignite were studied under the combustion conditions at temperatures ranging from 1037 to 1337 K. The characteristics of major pollution elements (nitrogen and sulfur) and their related functional groups on the surface of zhungeer (ZG) raw coal and chars were determined using the X-ray photoelectron spectroscopy (XPS) and element analysis. The research results showed that particle surface contained similar component of pyridinic and pyrrolic nitrogen and had six kinds of sulfur functionalities. Moreover, functional groups of major pollution elements on particle surface presented different evolution trends during combustion. 

Effects of Upgrading Treatment on the Physicochemical Structure, Moisture Re-Adsorption Ability, and NOx Emission Characteristic of Lignite Particles

“…This phenomenon could be attributed to the structural change of functionalities and aromatic ring systems after upgrading treatment under different conditions. The increase of drying temperature led to more obvious variations in the thermal stability of aromatic ring systems, reducing the activation energy of N-5 decomposition, which was the precursor of HCN from the particle surface. , Meanwhile, H 2 O molecules could decompose into hydrogen radicals and hydroxyl groups under high-temperature conditions . The oxidizing hydroxyl groups tended to oxidize HCN into NO, weakening the heterogeneous NO reduction ability of coal particles at the initial combustion stage.…”