Mechanism and experimental study of bimetallic solid catalysts on urea catalytic hydrolysis to ammonia

In order to solve the problems of slow reaction rate and large reactor volume of traditional urea hydrolysis to ammonia, the urea catalytic hydrolysis was studied in this paper. The bimetallic solid catalyst TiO2@Al2O3 was synthesized firstly, in which the mesoporous ?-Al2O3 was selected as substrate and the TiO2 was inserted into the active site. The solid catalyst was characterized by Raman spectroscopy and transmission electron microscopy, and the intermediates were qualitatively detected by liquid NMR H-spectroscopy and C-spectroscopy, which was combined with density functional theory calculations to analysis the mechanism of the bimetallic solid catalyst. Then, the kinetic and thermodynamic properties of the urea catalytic hydrolysis by solid catalyst were investigated on a batch reactor and a continuous operation pilot plant. The kinetic parameters of the catalytic hydrolysis reaction were measured, and the influences of different catalysts on the hydrolysis reaction temperature, energy consumption and variable load response time were researched. The bimetallic solid catalyst proposed in this study can solve the problems of phosphorus-containing wastewater discharge and insufficient active sites of traditional catalysts, and will provide significant reference to the research of urea catalytic hydrolysis to ammonia for flue gas denitrification.