Kinetic modeling of low temperature catalytic steam gasification of Powder River Basin coal and petcoke

A semi-batch fixed differential bed reactor was designed and built to obtain the data in real time for the analysis of kinetics for low temperature catalytic steam gasification of Power River Basin coal and petcoke. The kinetics for various pure alkali metal salt and alkali metal base (KOH, NaOH, Na2CO3 and K2CO3) catalysts were studied for steam-char gasification at 700°C. The effectiveness of these four catalysts were in the order of KOH > K2CO3 > NaOH > Na2CO3 > raw coal. The effect of steam flow rates on coal-char gasification was studied. At higher steam to carbon ratio, it showed a higher concentration of CO2 and H2 and vice versa. Also, at a lower steam to carbon ratio, methane formation was more favorable compared to the higher steam to carbon ratio. The study on the effects of purge gases like H2 and H2:CO (2:1) showed an inhibition effect on all the catalyst systems. The empirical reaction orders of these catalytic gasification were determined for different purge gases used in the range of zero to first order. A detail of the gas composition under different steam and catalytic gasification conditions were recorded.