Mechanism and experimental study on urea catalytic hydrolysis for ammonia

In order to solve the problems such as slow reaction rate in the urea hydrolysis for ammonia，a weakly alkaline ammonium salt was selected in this research，which promoted the urea decomposition by increasing the alkalinity of the reaction solution．The lab-scale test and pilot test results indicated that，(NH4)2HPO4 has higher catalytic efficiency than NH4H2PO．The activation energy of the hydrolysis reaction is decreased from 73.6 kJ/mol without the catalyst to 65.3 kJ/mol when using the (NH4)2HPO4 as catalyst，thus the hydrolysis reaction rate is accelerated，and the reaction temperature can be reduced by about 10°C while the energy consumption for ammonia production is reduced by about 3%．Under the same ammonia production requirement and reaction temperature，the volume of the catalytic hydrolysis reactor can be reduced by more than 30%．The urea hydrolysis with catalytic still belongs to slow liquid-phase reaction，and the ammonia production rate is controlled by the intrinsic kinetics． This research will provide an important reference for the process design of urea catalytic hydrolysis. © 2023 Huazhong University of Science and Technology. All rights reserved.