Patent ID: 8604226

Claim:
A process for preparing alpha-sulfo-fatty acid ester salt surfactants, comprising the following steps: (1) sulfonation: sulfonating a fatty acid ester with sulphur trioxide to prepare a crude sulfonic acid; (2) bleaching: bleaching the crude sulfonic acid obtained in step (1) by using hydrogen peroxide as bleaching agent; (3) secondary esterification: subjecting the product of step (2) to a secondary esterification using an alcohol as esterifying agent; (4) neutralization: neutralizing the product of step (3) with a base; and (5) drying: drying the product of step (4) to obtain a powdery product, wherein the bleaching agent is fed by means of a spray and is mixed homogeneously using a rotor film-scrapping shear mixer to ensure sufficient reaction, and wherein the bleaching is cooled down by a cold air blast or room-temperature blast to remove heat generated in the process.