Significance of the reduction of alkali carbonates in catalytic carbon gasification

Kinetics of carbon dioxide gasification of fast pyrolysis black liquor char

“…For sodium or potassium carbonate catalyzed gasification, it is suggested (Sams and Shadman, 1986) that the catalytic sites are reduced alkali metal intermediates formed by reactions 1 and 2 subsequently (-COM) + C ~(-CM) + CO (4a) Catalyst evaporation occurs upon prolonged reduction of the char during pyrolysis under inert conditions (Shadman et al, 1987) and can be represented by…”

Catalytic Coal Gasification

“…Sam and Shadman [19,20] suggested the formation of possible carboxylic (eCO 2 K), phenolic (eCOK) or even completely reduced potassiumecarbon (eCK) groups. The third step (R18) symbolizes site regeneration, which requires mobility on the part of the potassium.…”

Changes in char reactivity due to char–oxygen and char–steam reactions using victorian brown coal in a fixed-bed reactor

“…The gasification reactions in the quartz reactor at 800°C could possibly lead to the rearrangement of inherent catalytic species (i.e. Na and K) and more metallic species migrated to the surface of char with longer feeding (reaction) time [28,29]. The dispersion of abundant metal species on the char surface may explain the high ex-situ reactivity of chars with long feeding time.…”

“…As explained for Fig. 3(a), the longer holding time probably has also allowed more inherent catalytic metal species to accumulate on the char surface [28,29], thus featuring high reactivity. Additionally, the increase in coal conversion with increasing holding time indicates the slow increase in Na/K content in the resultant chars [15].…”