P-aminophenol catalysed production on supported nano-magnetite particles in fixed-bed reactor. Kinetic modelling and scale-up

The aim of this work was to investigate on the possibility to use nano-magnetite particles supported on waste biomass as heterogeneous catalyst for the production of p-aminophenol starting from a well-known pollutant, p-nitrophenol, in fixed-bed reactors. The kinetic and the thermodynamic of the process was firstly studied in batch system, subsequently a first scale-up was performed using a glass column packed with the supported catalyst. The experimental data obtained with the column were interpreted in light of a suitable dynamic model. The Langmuir-Hinshelwood mechanism well described the process, obtaining from the data fitting a surface rate kinetic constant k = 2.68 × 10−6 mol/m2·h, an adsorption equilibrium constants for PNP and BH4− species equal to 20.07 l/mol and 1.83 l/mol, at 25 °C. The Eyring equation was used to fit the apparent kintic constant variation with the temperature, to estimate thermodynamic parameters, obtaining a ΔH = − 1145.68 kJ/mol and ΔS = −315.02 kJ/K·mol. The process was then simulated in PROII environment, investigating the influence of initial PNP flowrate, NaBH4/PNP and reactor length/diameter ratios on PNP conversion, on required duty to maintain isothermal conditions and on pressure drops in the reactor.