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 N-2. 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. H-2 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 H-2 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 H-2 production from coal should be caused by tar produced from coal in the initial stage and especially that H-2 production in the second stage should be by char from coal.