Gasification process using ion-exchanged coal

Abstract

A process wherein Group I-A or Group II-A metals, or both, can be ion-exchanged onto coal, especially a high rank coal, notably a subbituminous or bituminous coal, to produce a highly reactive carbonaceous feed for use in gasification reactions, especially to produce high-BTU fuel gases, but also intermediate-BTU or synthesis gas. The coal is treated by contact with an alkaline solution of an admixture of compounds, inclusive of a soluble alkali metal salt and an excess of an alkaline earth metal hydroxide, each of which interacts one with the other to form an alkali metal hydroxide, and an insoluble alkaline earth metal salt precipitate. The coal is treated in a single step by contact with the solution within which both the Group I-A and II-A metal compounds are dispersed, or dissolved. Where the coal does not contain adequate ion-exchange sites, these are formed by reaction between the alkali metal hydroxide, generated by the reaction, and the coal, and in turn all or a portion of the alkali metal cations are exchanged or replaced by alkaline earth metal cations which are present in the alkali metal hydroxide solution that is formed. Preferably, the treatment is continued until substantially all of the alkali metal cations have been replaced by the alkaline earth metal cations, and then the solution is evaporated while in contact with the coal to redeposit and physically disperse the alkali metal upon the coal.