Combustion Performance and Mechanism of Sodium-Impregnated Loy Yang Lignite

Na + is one typical alkali metal ion in Loy Yang lignite (LY). To investigate the mechanism of Na + catalyzing LY combustion, Na + was implanted into the acid-washed LY using an impregnation method, and the combustion performance of all samples was studied using thermogravimetric analysis. Activation energy ( E ) was calculated using the Kissinger–Akahira–Sunose equation. Moreover, the Fourier transform infrared spectrum, X-ray diffraction pattern, and pore size distribution were also analyzed. The results showed that the implanted Na + was in the type of amorphous state carboxylates. The peak temperature ( T p ) values of the Na + -impregnated samples decreased compared with that of the acid-washed sample, and T p decreased as the Na + content increased. The opposite result was found for the maximum combustion rate (MCR). According to the changes in the T p , MCR, and E , a mechanism of Na + catalyzing LY combustion is proposed. Na + enhances the devolatilization and burning of volatiles and char during LY combustion. Moreover, the Na + functions as an oxygen carrier, promoting the transport of oxygen, and it also block partial pores, hindering the transport of oxygen. The final combustion reactivity is determined by the competitive effects of the above two sides.