A composite catalyst for the production of hydrazine hydrate via the urea process and a method for preparing hydrazine hydrate.

Abstract

This application provides a composite catalyst for the production of hydrazine hydrate using the urea process, comprising the following components by mass percentage: magnesium sulfate heptahydrate; aminotrimethylenephosphonic acid; and sodium hexametaphosphate. A catalytic preparation method for hydrazine hydrate using the urea process includes: preparing a mixed base solution of urea and sodium hydroxide, with a free alkali concentration of 10%–10.5% and a pH of 13.0 ± 0.2; sequentially adding aminotrimethylenephosphonic acid and sodium hexametaphosphate, stirring until homogeneous, then adding magnesium sulfate heptahydrate, and continuing stirring to form a homogeneous complex catalytic system; uniformly adding sodium hypochlorite solution, maintaining a molar ratio of urea to sodium hypochlorite of 1.1–1.2:1, and a reaction temperature ≤ 40°C; maintaining the reaction temperature for 8–12 min after the addition is complete, followed by cooling to obtain crude hydrazine hydrate solution. This application can significantly improve the main reaction rate, suppress the occurrence of side reactions, and effectively prevent Ca from accumulating in the alkali recycling process. 2+ Calcium carbonate precipitate forms, clogging the pipes.

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