KINETIC MODELLING OF A POLYPHASIC REACTOR BY PRE-DETERMINATION OF PHASES EQUILIBRIA INVOLVED
Advancing the chemical engineering fundamentals
Chemical Reaction Engineering (T2-2P)
Keywords: hydrazine, kinetic modelling, polyphasic reactor, phases equilibria
Within the framework of the development of the synthesis of a hydrazine precursor of a hypoglycaemic medication, this work focus on the modelling of a piston flow reactor which presents, in steady state conditions, a double diphasic and monophasic segments. This case arises in the second step of the elaboration of N-N bonding, by action of monochloramine with an excess of amine in strongly alkaline medium.
First step : NH3 + OCl-→ NH2Cl + OH- (monophasic medium)
Second step : NH2Cl + R1R2NH → R1R2NNH2 + HCl
HCl + NaOH → NaCl + H2O (diphasic + monophasic medium)
In this configuration, amine and sodium hydroxide are responsible of a transient miscibility gap. The partial neutralization of excess NaOH by formed HCl leads, at the time t = t’ and for the degree of advancement of the reaction e = e’, to a rupture of the polyphasic state and the continuation of the reaction in a homogenous medium.
The developed method consists in calculating the variation of the diphasic system according to e. The successive preparation of mixtures (e = 0 ; e = 0.1 ; e = 0.2 …; e = e’) allows to determinate the different variables (concentrations of each component in the two phases and volume of each phase) as a function of e, by physico-chemical analysis of the two phases in equilibrium. Then, it is possible to determine the value e’ from which the medium becomes homogeneous.
Taking into account the distribution of the reagents between the phases in equilibrium, we developped an equation which permits to follow the evolution of the instantaneous concentrations of each component as a function of the time by considering the effect of the chemical transformation and the variation of volume v.
The presented work permits to establish the residence time of the diphasic and monophasic segments whatever the experimental conditions.
See the full pdf manuscript of the abstract.
Presented Tuesday 18, 13:30 to 15:00, in session Chemical Reaction Engineering (T2-2P).
