The stability and activity of alkaline carbonate catalysts in supercritical water coal gasification has been investigated using density functional theory method.Our calculations present that the adsorption of Na_2CO_3 on coal are more stable than that of K2CO3,but the stability of Na_2CO_3 is strongly reduced as the cluster gets larger.In supercritical water system,the dispersion and stability of Na_2CO_3 catalyst on coal support is strongly improved.During coal gasification process,Na_2CO_3 transforms with supercritical water into NaOH and NaHCO_3,which is beneficial for hydrogen production.The transformation process has been studied via thermodynamics and kinetics ways.The selectively catalytic mechanism of NaOH and the intermediate form of sodium-based catalyst in water-gas shift reaction for higher hydrogen production has also been investigated.Furthermore,NaOH can transform back to Na_2CO_3 after catalyzing the water-gas shift reaction.Thus,the cooperative effects between supercritical water and Na_2CO_3 catalyst form a benignant circle which greatly enhances the reaction rate of coal gasification and promotes the production of hydrogen. The stability and activity of alkaline carbonate catalysts in supercritical water coal gasification has been investigated using density functional theory method. These calculations present that the adsorption of Na_2CO_3 on coal are more stable than that of K2CO3, but the stability of Na_2CO_3 is strongly reduced as the cluster gets larger.In supercritical water system, the dispersion and stability of Na_2CO_3 catalyst on coal support is strongly improved. Fluid coal gasification process, Na_2CO_3 transforms with supercritical water into NaOH and NaHCO_3, which is beneficial for hydrogen production.The transformation process has been studied via thermodynamics and kinetics ways. The selectively catalytic mechanism of NaOH and the intermediate form of sodium-based catalyst in water-gas shift reaction for higher hydrogen production has also been investigated. Morerther, NaOH can transform back to Na_2CO_3 after catalyzing the water- gas shift reaction.Thus, the cooperative effects between supercri tical water and Na_2CO_3 catalyst form a benignant circle which greatly enhances the reaction rate of coal gasification and promotes the production of hydrogen.