Catalytic gasification characteristics of mixed black liquor and calcium catalyst in mixing (air/steam) atmosphere

The catalytic effect of single and mixed catalysts including two single catalysts with 3% Ca and 5% Na-BL, and one 3% Ca+5% Na-BL mixed catalyst on carbon conversion, gasification reaction rate, relative amount of harmful pollutant like sulphur containing gases under temperature ranging from 750°C to 950°C and ambient pressure conditions were investigated by thermogravimetry in mixing (air/steam) gasification for three high-metamorphous anthracites of Longyan, Fenghai, and Youxia coals. The mixed BL+Ca catalyst has a synergetic effect in comparison with only using single BL and Ca catalyst. At mixing gasification the mixed catalyst of 3% Ca+5% Na-BL greatly increases the carbon conversion and reaction rate by accelerating the reactions of C+CO2→2CO and C+H2O→CO+H2 because of the presence of alkali surface compounds [COM] and [CO2M], and exchanged calcium phenolate and calcium carboxylate (COO)2. This catalytic action is stronger than steam gasification. By adding CaCO3 into BL catalyst in gasification less than 900°C, the catalytic ability is improved with increasing coal conversion and effective desulphurization.