Regeneration of acid containing peroxy acids of sulfur
View Patent ↗A method of treating a spent oxidizing acid is provided comprising the steps of contacting a spent acid containing peroxy acids of sulfur with a quantity of SO 2 in excess of an equilibrium quantity required to convert the peroxy acids to sulfuric acid. The excess SO 2 is catalytically converted to SO 3 , and the SO 3 is absorbed into the sulfuric acid stream essentially free of H 2 SO 5 and H 2 O 2 to make product sulfuric acid.
1. A method of treating a spent oxidizing acid, comprising the steps of:
contacting a spent oxidizing acid comprising sulfuric acid and at least one of H 2 SO 5 and H 2 O 2 with a quantity of SO 2 in excess of a stoichiometric quantity required to convert the at least one of H 2 SO 5 and H 2 O 2 to sulfuric acid and produce an excess SO 2 stream and a sulfuric acid stream essentially free of H 2 SO 5 and H 2 O 2 ;
catalytically converting SO 2 in the excess SO 2 stream to SO 3 ; and
absorbing the catalytically converted SO 3 into the sulfuric acid stream essentially free of H 2 SO 5 and H 2 O 2 to make a product sulfuric acid.
2. The method of claim 1 , wherein the spent oxidizing acid comprises spent Piranha solution.
3. The method of claim 1 , wherein the spent oxidizing acid comprises greater than 65 wt % sulfuric acid.
4. The method of claim 1 , wherein the SO 2 reacts with greater than 98% of the at least one of H 2 SO 5 and H 2 O 2 .
5. The method of claim 1 , comprising contacting the spent oxidizing acid with a quantity of SO 2 in a gas stream containing air and greater than 8 vol % SO 2 .
6. The method of claim 1 , comprising contacting the spent oxidizing acid with a quantity of SO 2 in a gas stream containing air and between about 9 to about 12 vol % SO 2 .