Abstract：To investigate the characteristics of biurea synthesis from hydrazine hydrate and urea in acid-free environment, the concentration of hydrazine hydrate and the mass of biurea were measured in a closed batch reactor at different temperatures. The concentration of free ammonia in the reaction system was calculated and the solubility of biurea in water was determined. The results showed that the reactions of semicarbazide synthesis and biurea synthesis were both reversible, and they were first-order reactions with respect to all components. The kinetic models for the reactions of semicarbazide synthesis and biurea synthesis were established. The equilibrium constants, reaction rate constants and kinetic model parameters at different temperatures were obtained. The predicted results were in good agreement with the experimental data, which can be used for the optimization design of subsequent engineering applications.
