Abstract: In view of sulfur resources shortage in China and the problem that SO2 recycling cannot be realized by current
desulfurization technology，a method was proposed to reduce SO2 to elemental sulfur by using activated carbon powder as
reducing agent under gas-solid two-phase flow. The effects of reaction temperature，molar ratio of C/SO2，and concentration
of CO，H2，CO2 and water vapor on the reaction were studied. The results show that higher reaction temperature and C/SO2
molar ratio are conducive to improving the reduction efficiency and reaction rate of SO2 by activated carbon，and have little
effect on COS generation and lead to a high selectivity of elemental S. The addition of CO and H2 can significantly improve
the conversion rate of SO2，but a large number of S-containing by-products are generated during the reaction，leading to a
decrease in the selectivity of elemental S. CO2 has little effect on the whole reaction. The addition of H2O affects the Claus
reaction balance，resulting in the increase of H2S production and the significant decrease of the selectivity of elemental S.
The economic analysis indicates that the main cost of the process includes energy consumption for heating and reaction
material consumption of activated carbon. Every 1 g removed SO2 can produces 0.38 g sulfur，and consumes 0.16 g
activated carbon and 1.7 kJ energy. This study provides theoretical support for the carbothermal reduction of SO2 in
fluidized beds.

Key words: activated carbon, reduction, elemental sulfur, sulfur dioxide, drop-tube furnace, fluidized bed, recycling