Process for recovering sulphuric acid from sulphur containing by-products of a process for preparing 2-hydroxy-4-methylthiobutyric acid (MHA)

摘要

Recovery of sulfuric acid used in hydrolysis of methylmercaptopropionaldehyde-cyanohydrin is carried out by combustion of sulfates produced during the reaction to give a sulfur dioxide-containing mixture, which is then reacted with hydrogen peroxide. Recovery of sulfuric acid used in hydrolysis of methylmercaptopropionaldehyde-cyanohydrin (MMP-CH) comprises converting sulfate salt precipitates produced during the hydrolysis to SO2 in a furnace. The SO2-containing mixture is passed through an aqueous solution containing sulfuric acid and hydrogen peroxide, to convert the SO2 back to sulfuric acid. An Independent claim is also included for preparation of 2-hydroxy-4-methylthiobutyric acid (MHA) by hydrolysis of MMP-CH in the presence of sulfuric acid to give MHA and ammonium hydrogen sulfate and/or ammonium sulfate. The MHA is isolated and the sulfuric acid is recovered and recycled using the above method.