Ca. Bejarano et al., A study on carbothermal reduction of sulfur dioxide to elemental sulfur using oilsands fluid coke, ENV SCI TEC, 35(4), 2001, pp. 800-804
Citations number
18
Categorie Soggetti
Environment/Ecology,"Environmental Engineering & Energy
Experiments and reaction equilibrium calculations were carried out for the
SO2 gas and oilsands fluid coke system. The goal was to develop a coke-base
d sulfur-producing flue gas desulfurization (SP-FGD) process that removes S
O2 from flue gases and converts it into elemental sulfur. The conversion of
SO2 to elemental sulfur proceeded efficiently at temperatures higher than
600 degreesC, and the sulfur yield reached a maximum (>95%) at about 700 de
greesC. An increase of temperature beyond 700 degreesC enhanced the reducti
on of product elemental sulfur, resulting in the formation of reduced sulfu
r species (COS and CS2), which lowered the sulfur yield at 900 degreesC to
90%. Although equilibrium calculations suggest that a lower temperature fav
ors the conversion of SO2 as well as the yield of elemental sulfur, experim
ents showed no formation of elemental sulfur at 600 degreesC and below, lik
ely due to hindered kinetics. Faster reduction of SO2 was observed at a hig
her temperature in the range of 700-1000 degreesC. A complete conversion of
SO2 was achieved in about 8 s at 700 degreesC. Prolonging the product gas-
coke contact, the yield of elemental sulfur decreased due to the formation
of COS and CS2 while the SO2 conversion remained complete. Equilibrium calc
ulations suggest that the ultimate yield of elemental sulfur maximizes at t
he C/SO2 ratio of 1, which represents the stoichiometry of SO2 + C --> CO2
+ S. For the C/SO2 ratio < 1, equilibrium calculations predict elemental su
lfur and CO2 being major products, suggesting that SO2 + C --> CO2 + S is t
he predominant reaction if SO2 is in excess. Experiments revealed that elem
ental sulfur and CO2 were only major products if the conversion of SO2 was
incomplete, which is in agreement with the result of the equilibrium modeli
ng.