Embodiments described herein generally relate to a composite carbonate utilized as a catalyst in coal gasification processes. Methods described herein also include suitable processing conditions for performing coal gasification with the composite catalyst. In certain embodiments the composite catalyst may comprise an alkali carbonate and a transition metal carbonate, for example, an FeCO3—Na2CO3 catalyst. An FeCO3—Na2CO3 catalyst, compared to raw coal, may increase the carbon conversion rate by about two times within the 700° C.-800° C. range due to its ability to reduce the activation energy of gasification by about 30-40%. Compared to pure sodium and pure iron catalysts, the composite catalyst may increase the yields of desired products H2 and CO at 800° C. by 14.8% and 40.2%, respectively.