Characteristics of Hydrogen Production from Coal Tar with Subcritical Steam

A laboratory-scale batch reactor was used to perform a limited number of experiments on the steam gasification of coal tar formed by pyrolyzing Taiheiyo coal at 873 K for 2 h in N2. The study was intended to support the HyPr-RING process in which coal is gasified with steam in a fluidized bed containing Ca-based CO2 sorbent. H2 is the desired product, while substantial amounts of CH4 and small amounts of C2H6 were also produced. The amounts were decreased but the molar ratio of CH4 to H2 in the product gases was increased with a decrease of the temperature. The predominant production occurs in the initial stage including the heating period. The behavior for tar is similar to that for coal, suggesting that CH4 and H2 production from coal should be caused by tar produced from coal in the initial stage and especially that H2 production in the second stage should be by char from coal.