The Variability And Reaction Mechanisms Of Sulfides In The Process Of Black Liquor Gasification

Gaseous sulfides are produced in the process of black liquor gasification. These gaseous sulfides can pollute the air and can damage the follow-up combustion equipment or synthesis reactors. This paper focuses on the variability and reaction mechanisms of sulfides in the process of gasification. Based on the variability of sulfides, a tentative hypothesis of reaction mechanisms is proposed and then confirmed by the experimental evidence. The following conclusions can be drawn:(a) The conversions of Na2SO4, Na2S, Na2S2O3and lignin are53.6%,95.2%,92.7%and100%, respectively, and92.3%of the total sulfur (TS) was converted to gaseous sulfides including H2S, CS2, COS, CH3SH, CH3SCH3and CH3S S CH3.(b) The path of black liquor gasification reaction:after the pyrolysis reaction of lignin.H2, C, H2S, CH4, CO, CO2, H2O, CH3OH and other substances were produced in the teaction. Na2SO4and Na2S2O3which were in the black liquor were reduced by C and H2, then, Na2S, CS2, CO2, H2S and H2O was produced, Na2S were reduced by H2and CO2. H2S, Na2CO3, COS and Na was produced in the reaction.The COS was reduced by H2and H2O.The H2S was reduced by CH3OH which was produced in the pyrolysis reaction of lignin,resulting in CH3SH and H2O. CH3SH was reduced by CH3OH, resulting in CH3SCH3, CH3OCH3and CH3SSCH3.