Kinetic study of the synthesis of ammonium phosphates based on orthophosphoric acid and ammonia

Abstract

The synthesis of ammonium phosphates based on orthophosphoric acid and ammonia is a fundamental process in the production of phosphorus-containing fertilizers. This study investigates the reaction kinetics of ammonium phosphate formation through the neutralization of orthophosphoric acid with aqueous ammonia under controlled conditions. The effects of key parameters, including temperature, pH, reactant concentration, and reaction time, on the rate and mechanism of the process were systematically analyzed. Kinetic data were obtained and evaluated to determine the reaction order and activation energy, providing insight into the rate-controlling steps. The results indicate that the reaction proceeds through a multi-stage mechanism involving intermediate phosphate species, with pH playing a crucial role in determining the final product composition (NH₄H₂PO₄, (NH₄)₂HPO₄, or (NH₄)₃PO₄). Optimal synthesis conditions were identified to maximize product yield and purity. The findings contribute to improving the efficiency of ammonium phosphate production and provide a scientific basis for process optimization in industrial applications.