Determination of Sulfur Trioxide in Oleum/Nitric Acid Mixtures

摘要

A method of analysis is described for determination of the sulfur trioxide content of oleum/nitric acid mixtures found in the low temperature continuous TNT process. This method consists of the indirect determination of sulfur trioxide, via the water consumed by sulfur trioxide, using the Karl Fisher titration technique. Reaction products formed during the TNT production (e.g. nitrosylsulfuric acid, tetranitromethane, and nitroaromatics) do not interfere with the Karl Fisher titration. This method is rapid, has acceptable accuracy and precision, and is applicable to mixtures containing up to 21% sulfur trioxide in the presence of 11% nitrosylsulfuric acid.