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

• US 20100015040A1
• Filed: 12/21/2007
• Published: 01/21/2010
• Est. Priority Date: 04/09/2007
• Status: Active Grant

• Current Assignee: Korea Advanced Institute of Science and Technology
• Original Assignee: Korea Advanced Institute of Science and Technology
• Inventors: Yoo, Kye Sang, Kim, Chang Soo, Kim, Hong Gon, Jung, Kwang Deog, Gong, Gyeong Taek, Lee, Byung Gwon, Ahn, Byoung Sung, Joo, Oh Shim
• Granted Patent: US 7,749,475 B2
• Time in Patent Office: Days
• US Class Current: 423/658.200
• CPC Class Codes: B01D 53/1481 Removing sulfur dioxide or sulfur trioxide
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents
• CPC Class Codes: C01B 13/0229 Purification or separation processes
• CPC Class Codes: C01B 13/0285 by absorption in liquids
• CPC Class Codes: C01B 17/56 Separation; Purification
• CPC Class Codes: C01B 2210/0071 Sulfur oxides
• CPC Class Codes: Y02E 60/36 Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
• CPC Class Codes: Y02P 20/54 using solvents, e.g. supercritical solvents or ionic liquids

Abstract

The present invention relates to a method for separation and recycling of pure sulfur dioxide from a gaseous mixture in the IS cycle. More specifically, the present invention relates to a method for separation and recycling of pure sulfur dioxide from a gaseous mixture in the IS cycle using an ionic liquid under a specific condition. When compared with the conventional amine-based absorbent, the use of the ionic liquid enables continuous absorption and stripping of SO₂ even at high temperature, and enables a reversible absorption of SO₂ without loss, decomposition or degradation of a solvent due to good chemical stability, thereby enabling separation and recycling of pure SO₂ from a gaseous mixture in the IS cycle.

Claims

1. A method for separation and recycling of pure sulfur dioxide (SO2) from a gaseous mixture in the iodine-sulfur (IS) cycle, comprising:

contacting a gaseous mixture discharged from the IS cycle comprising decomposition of sulfuric acid (H2SO4), Bunsen reaction of SO2 and decomposition of hydrogen iodide (HI) with an ionic liquid, thereby absorbing and separating SO2 contained in the gaseous mixture by the ionic liquid; and

degassing the absorbed and separated SO2 from the ionic liquid.

2. The method for separation and recycling of pure SO2 according to claim 1, wherein the absorption and separation of SO2 is performed at 20 to 50°

C.

3. The method for separation and recycling of pure SO2 according to claim 1, wherein the stripping is performed at 120 to 250°

C.

4. The method for separation and recycling of pure SO2 according to claim 1, wherein the ionic liquid is an ionic compound comprising a cation selected from imidazolium, pyrrolidinium, piperidinium, morpholinium and pyridinium and an anion selected from hydrogen sulfate (HOSO3-), methyl sulfate (CH3OSO3-), ethyl sulfate (C2H6OSO3-), methanesulfonate (CH3SO3-), acetate (CH3COO—

), tetrafluoroborate (BF4-), hexafluorophosphate (PF6-) and chloride (Cl—

) or a mixture thereof.

5. The method for separation and recycling of pure SO2 according to claim 1, wherein the ionic liquid is imidazolium acetate, imidazolium chloride or a mixture thereof.

6. The method for separation and recycling of pure SO2 according to claim 1, wherein the ionic liquid is used in an amount from 1.5 to 5.0 mols based on 1 mol of the gaseous mixture discharged from the IS cycle.

7. The method for separation and recycling of pure SO2 according to claim 1, wherein the gaseous mixture discharged from the IS cycle includes 40 to 80 weight % of SO2 and 20 to 60 weight % of oxygen (O2).

8. The method for separation and recycling of pure SO2 according to claim 1, wherein the separation and recycling of SO2 is performed continuously in an absorption tower and a stripping tower.

9. The method for separation and recycling of pure SO2 according to claim 1, by which SO2 is recycled with recovery rate of 85 to 95% and purity of 98 to 99%.

10. The method for separation and recycling of pure SO2 according to claim 4, wherein the ionic liquid is imidazolium acetate, imidazolium chloride or a mixture thereof.