Catalytic CO2 gasification of a Powder River Basin coal

• CO2 was used as gasifying agent for gasifying a Powder River Basin coal.
• The composition of main gas products during coal pyrolysis was studied.
• XRD was used to detect the sodium forms during the coal char gasification.
• Grain, integrated, and random pore models were used in the kinetic analysis.

CO2 gasification of Wyodak low-sulfur sub-bituminous coal from the Powder River Basin (PRB) of Wyoming was conducted in a fixed-bed laboratory gasifier at atmospheric pressure with Na2CO3, an inexpensive catalyst widely available in Wyoming. The sodium effect on the coal pyrolysis and the sodium forms existing during the char gasification were investigated using thermo-gravimetric analyses (TGA) and X-ray diffraction (XRD) analyses, respectively. Sodium was found to decrease the tar production and promote the char condensation during the pyrolysis. The interaction between added sodium and the minerals in Wyodak coal were observed during the char gasification. Grain, integrated, and random pore models were employed to fit the kinetic data obtained under both non-catalytic and catalytic conditions. The apparent activation energies of the coal-CO2 gasification without and with use of the catalyst (3 wt.% Na) are ~ 91 kJ/mol and ~ 64 kJ/mol, respectively, a 30% decrease. Thus, Na2CO3 is a promising catalyst for the PRB coal-CO2 gasification.

Figure optionsDownload as PowerPoint slide