Optimization process parameters for in-situ synthesis of ammonia by catalytic hydrolysis of urea with fly ash in a batch reactor for safe feedstock in power plants

Abstract

In this study, catalytic urea hydrolysis for production of ammonia in presence of fly ash, at optimum condition, was investigated in a batch reactor. The single and combined effects of operating parameters such as initial feed concentrations, temperature, fly ash doses, times and stirring speed on the production of ammonia from urea were analyzed using response surface methodology. A 25 full factorial central composite experimental design was employed. Analysis of variance (ANOVA) showed a high coefficient of determination value (R2= 0.963) and satisfactory prediction second order regression model was derived. The optimum production conditions were determined as initial feed concentration 19.9 wt. % of urea, temperature 175°C, fly ash dose 7.5g/L, reaction time 25 min and stirring speed 769 rpm. At optimum conversion conditions, the conversion of urea for production of ammonia was found to be 99.8 %.