The effects of alkali and alkaline earth metals such as potassium (K) and calcium (Ca) on CO2 gasification reactivity of Japanese cypress (hinoki) char under various temperatures (1123-1223 K) and CO2 concentration (20-80 vol.%) were studied using thermal gravimetric analysis. The presence of K and Ca compounds in char improved the reactivity of hinoki char for CO2 gasification catalytically. It was also confirmed that K and Ca compounds can be supported on char to exhibit an enhanced catalytic effect during CO2 gasification of K-char and Ca-char. The char gasification rate increased with the increase of CO2 concentration at higher temperatures (1173-1223 K), however at lower temperature (1123 K) the gasification rate decreased at 80% CO2. The retardation of char gasification rate at higher CO2 concentration is caused by the inhibition effect of CO: CO is disproportionated on alkali metal catalysts to CO2 and carbon, and affected the CO2 gasification rate. The dependence of char gasification rate on reaction temperature yielded a straight line in an Arrhenius-type plot which indicated that there was no significant change in the gasification mechanism in the temperature range of 1123-1223 K.
- Alkali and alkaline earth metals
- Biomass char
- CO gasification
ASJC Scopus subject areas
- Chemical Engineering(all)
- Fuel Technology
- Energy Engineering and Power Technology