In Situ Study on K2CO3-Catalyzed CO2 Gasification of Coal Char: Interactions and Char Structure Evolution

To investigate the interactions between K2CO3 and coal char, a fixed-bed reactor was used to conduct catalytic pyrolysis and gasification of coal char. An in situ Raman spectroscopy system was applied to characterize the evolution of char structure. Three different ranks of Chinese coals were deashed first and pyrolyzed to chars before experiment. In catalytic pyrolysis of coal char, the release of CO proved that reactions occurred between K2CO3 and char and the release of a small amount of CO2 was connected with the oxygen content. In situ Raman spectra results showed that the char structure order decreased with rising temperature for the production of an intermediate. During the gasification process, the char structure order decreased first and then increased, attributed to the evaporation of K at high temperature. The ex situ data revealed that the intermediate did not exist at room temperature. For better understanding of the true form of chars at high temperature, an in situ Raman spectrometer is necessary.