Intrinsic kinetics of hydrogenation of p-nitrophenol over palladium catalytic membrane

The palladium catalytic membrane was prepared by the flow-through method with the palladium nanoparticles immobilized on the ceramic membrane. The intrinsic kinetics of catalytic hydrogenation of p-nitrophenol over the palladium catalytic membrane was studied. The effects of rotation rate of peristaltic pump, p-nitrophenol concentration, sodium borohydride concentration and temperature on the initial reaction rate of p-nitrophenol were investigated, and a power function equation was used to fit the data. When the rotation rate was over 50 r/min, the effect of external diffusion could be ignored. The particle size of palladium in the as-prepared palladium catalytic membrane was about 5 nm and the effect of internal diffusion could be ignored. As a result, the reaction was controlled by the kinetics. The orders of the reaction were found to be 0 for p-nitrophenol and 0.75 for sodium borohydride, respectively. The reaction activation energy was 8.45 kJ/mol and the pre-exponential factor was 4.24 mmol^0.25/(L^0.25 ·min). According to the above works, the intrinsic kinetic model was established. The calculated initial reaction rates of p-nitrophenol were in good agreement with the experimental results, and the average relative error was 5%. This study would provide the fundamental data for development of palladium catalytic membrane and membrane reactor.