Na2CO3 catalyzed CO2 gasification of coal char and its intermediate complexes

Abstract

The catalytic effect of Na2CO3 on the CO2 gasification of Zhundong coal char was analyzed using the thermo-gravimetric analyzer. Besides, the structural characteristics of the sodium-added chars were examined using scanning electron microscopy (SEM), X-ray photoelectric spectroscopy (XPS), confocal laser scanning microscopy (CLSM), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy. The results indicate that the Na2CO3 induces the remarkably promotional effect on the CO2 gasification of the Zhundong coal char. As the catalyst content increased from 2.5 to 10 wt%, the reactivity index increases by approximately eight times. Furthermore, the SEM, CLSM and Raman reveal that the addition of Na2CO3 contributes to the formation of disordered and amorphous carbon structure. The sodium-added chars exhibit relatively rough morphology with the multi-particles and large size of pores. In addition, the Na2CO3–carbon interactions occur at low temperature, together with the release of CO2. As the temperature increased, complex precursors containing O and Na start to generate. The existence of the complex –CONa is proven through the analysis of the XPS and FT-IR results. These complexes make it easy for CO2 to attack the char, thereby prompting the gasification reactivity of the Zhundong char.