Effect of mineral matters in biomass on the gasification rate of their chars

Abstract

In order to develop the effective utilization of biomass, the gasification behavior (changes in gasification rates against conversion) of various chars prepared from biomass at 1,000°C was studied. The gasification rate of char with CO2 measured at 900°C by a thermogravimetric balance was affected by the content of indigenous mineral matter such as calcium and potassium. The gasification behavior of chars were classified into following three groups: (1) the gasification rate reached a maximum in the higher conversion region, (2) the gasification rate profile showed two peaks around char conversion of 0.2 and 0.6 or higher, (3) the gasification rate profile fitted the random pore model. An increase in the gasification rate in a higher char conversion region was attributed to the promotion effect of the potassium catalyst. The number of active centers in the char was obtained by the O2 uptake at 200°C using pulse technique. The number of active sites was increased by potassium and calcium in biomass and the amount of O2 uptake well correlated the char gasification rate.