A method for preparing high-purity disodium hydrogen phosphite by coupling endogenous antioxidant reaction with crystallization in situ

Abstract

This application relates to a method for preparing high-purity disodium hydrogen phosphite through an in-situ coupled endogenous antioxidant reaction and crystallization process, belonging to the field of disodium hydrogen phosphite preparation technology. This application utilizes sodium hypophosphite as an endogenous antioxidant sacrificial agent to preferentially consume dissolved oxygen, combined with a constant pH mode for precise metering feed to eliminate impurities at the source; simultaneously, it employs a reaction-evaporation in-situ coupled crystallization process, allowing the neutralization reaction and crystallization to proceed simultaneously. The continuous precipitation of solid-phase products constantly removes the product from the liquid phase, maintaining the system in a metastable supersaturated state and improving the overall crystallization yield; combined with aging, gradient cooling, and ultrasonic treatment, it achieves precise control of the entire crystal growth process. This preparation method improves product purity and yield without requiring inert gas protection.