Release characteristics of gaseous products during CO2 gasification of char

Abstract

We investigated the release behaviors and reaction reactivities of gaseous products during CO2 gasification of three chars (Guanghui char, Hongshagang char, and Shenmu char) and graphite using thermogravimetric–mass spectrometry. The three chars with different sulfur contents had similar release behaviors. CO was the primary gaseous product, while SO2 was the main gaseous sulfur product. CO forms through the reaction between carbon and CO2. The temperature ranges at which H2 and COS evolved are similar to that of CO, and both H2S and SO2 were released at around 1100 °C. For the same gas, the differences in release behaviors were mainly due to the reactivity of the evolution reactions. Alkali mineral species had a catalytic effect on char gasification, while the increasing degree of graphitization tended to increase gasification reaction resistance. Larger surface area resulted in decreased reaction resistance at the initial stage of the gasification reaction. The most important factor influencing sulfur release reactivity was gasification activity rather than sulfur species in char. Moreover, acidic minerals may accelerate the release of sulfur.