METHOD FOR THE SEPARATION AND RECYCLE OF PURE SULFUR DIOXIDE FROM GASEOUS MIXTURE IN THE IS CYCLE WITH IONIC LIQUIDS

摘要

A method is provided to separate and recover pure SO2 only from a gas mixture generated from an IS(Iodine-Sulfur) cycle process even at a high temperature in a stable and succeeding manner through absorption and degassing processes using ionic liquid, and prevent loss of a solvent even in the repeated absorption and degassing processes by maintaining low vapor pressure and high temperature stability as compared with a conventional amine-based absorbent. As a method for separating and recovering sulfur dioxide from a gas mixture containing 40 to 80 wt.% of sulfur dioxide(SO2) and 20 to 60 wt.% of oxygen exhausted from an IS(Iodine-Sulfur) cycle process consisting of a decomposition reaction of sulfuric acid, a decomposition reaction of sulfur dioxide, and a decomposition reaction of iodic acid, a method for separating and recovering pure sulfur dioxide from the gas mixture in the IS cycle process using ionic liquid comprises the steps of: contacting the gas mixture with ionic liquid to allow the ionic liquid to absorb and separate sulfur dioxide(SO2) in the gas mixture in a temperature range of 20 to 50 deg.C; and degassing the sulfur dioxide that has been absorbed and separated from the gas mixture from the ionic liquid in a temperature range of 120 to 250 deg.C. The ionic liquid is ionically bonded compounds in which cations selected from imidazolium, pyrrolidinium, piperidinium, morpholinium and pyridinium are bonded with anions selected from hydrogen sulfate(HOSO3^-), methyl sulfate(CH3OSO3^-), ethyl sulfate(C2H6OSO3^-)methane sulfonate(CH3SO3^-), acetate(CH3COO^-), tetrafluoroborate(BF4^-), hexafluorophosphate(PF6^-), and chloride(Cl^-), or mixtures of the ionically bonded compounds. Further, the recovered sulfur dioxide has a recovery rate of 85 to 95% and purity of 98 to 99%.