Relation of coal properties to gasification reactivity and the effect of alkali metal catalysts on the kinetics of coal gasification. Final report, January 1972-March 1978
Chars derived from a large number of coal and coal maceral concentrates, varying in rank from anthracite to lignite, have been gasified in hydrogen, steam-hydrogen, and synthesis gas mixtures in a thermobalance apparatus at temperatures from 1400 to 1700F and pressures from 4 to 69 atmospheres. The reactivity factors for different coals were analyzed for possible correlation with such properties as elemental composition, petrographic properties, development of internal surface area and porosity during gasification, and concentration of exchangeable cations (sodium and calcium). A direct correlation between relative reactivity factor and the carbon content of the parent coal was established. The above correlation was applicable to lignites only when the raw lignite was initially treated with acid to remove the exchangeable cations. The sodium and calcium concentrations in 2 lignite samples were varied by acid washing followed by base exchange. For the derived chars, sodium was a more efficient catalyst compared with calcium for gasification in hydrogen. For gasification in steam and steam-hydrogen mixture, the rate for these chars, unlike those in hydrogen, was independent to total pressure. Within the range of catalyst concentration used (up to 3.5% by weight of char), both sodium and calcium enhanced the rate of gasification in proportion to their concentration in the chars
Book, 1980