Caution: I presume the sulfonic radical could separate in a water phase, if that is possible you have taken a couple steps toward making "polythionic" acid which can stress crack any sensitized (weld HAZ) austenitic SS (304, 316). Stabilized grades (321, 347 ) are resistant.
I jsut checked and the MOC for P-TSA acid is 316L SS. They use a low sulfuric aid grade of p-TSA. All I could get it's under 10% Sulphuric Acid in the p-TSA.
With our process the use of 316L is required because of the corrosive nature of the Carboxylic Acids above their melting points and the free H2SO4 in the p-TSA.