Kinetics of vinyl acetate emulsion polymerization in a pulsed tubular reactor: comparison between experimental and simulation results

Abstract

-A new reactor, the pulsed sieve plate column (PSPC), was developed to perform continuous emulsion polymerization reactions. This reactor combines the enhanced flexibility of tubular reactors with the mixing behavior provided by sieved plates and by the introduction of pulses that is important to prevent emulsion destabilization. The main objective of this work is to study the kinetics of vinyl acetate (VA) emulsion polymerization reactions performed in this PSPC. Therefore, both experimental studies and reaction simulations were performed. Results showed that it is possible to obtain high conversions with rather low residence times in the PSPC.

Simulation of emulsion copolymerization reactions in a continuous pulsed sieve-plate column reactor

“…The mathematical model is based on a previous model of Sayer et al (2002a) of emulsion homopolymerization reactions in the PSPC. In the elaboration/complementation of this model the following assumptions are made: § Monomer concentrations in polymer particles, monomer droplets and aqueous phase are at thermodynamic equilibrium and are computed using the iterative procedure proposed by Omi et al (1985).…”

“…The balance equations of continuous homopolymerization reactions in the PSPC were presented in Sayer et al (2002a) and are shown in the Appendix. In the present work the following average coefficients were used to describe the copolymerization reactions:…”

“…The model developed was implemented in FORTRAN and differential and algebraic equations were solved by the DASSL solver (Petzold, 1982). The model had been validated previously with experimental data on vinyl acetate emulsion homopolymerization reactions conducted at 55 o C in the PSPC (Sayer et al, 2002a). All simulations were carried out using the method of lines with 50 internal points evenly distributed in the axial direction.…”

“…In previous work (Palma et al, 2001a(Palma et al, , 2001bSayer et al, 2002aSayer et al, , 2002b a new type of reactor, the pulsed sieve-plate column (PSPC), had been studied for emulsion vinyl acetate homopolymerization reactions. It had been observed that transforming batch emulsion polymerization reactions into continuous reactions in a PSPC may be an attractive way to intensify this process since: 1) high conversions can be achieved in short residence times; 2) the process is safer in the PSPC than in a stirred tank batch or continuous reactor, due to the high heat exchange capacity of the PSPC and 3) due to the continuous operation, variations in product quality, which are commonly found from one batch to the next, are avoided.…”

Desenvolvimento de processo contínuo de copolimerização em emulsão em reator tubular.

“…Em ambos os casos, as pulsações causam turbulências suficientes para dificultar a deposição das partículas de polímero nas paredes e nos internos do reator, evitando entupimentos e incrustações, além de propiciar uma boa mistura radial para o transporte de calor. Em trabalhos anteriores do grupo CARVALHO et al, 2006a;CARVALHO et al, 2006b;CARVALHO et al, 2006c;PALMA, 2002;PALMA e GIUDICI, 2001;PALMA e GIUDICI, 2003;PALMA et al, 2001a;PALMA et al, 2001b;SALLARÉS et al, 2004;SAYER e GIUDICI, 2002a;SAYER e GIUDICI, 2002b;SAYER et al, 2002a;SAYER et al, 2002b), foi estudado o uso da coluna pulsada com pratos perfurados (CPPP) para a realização de reações de homopolimerização de acetato de vinila e de copolimerização de acetato de vinila e acrilato de butila em emulsão. Neste caso, as pulsações produzidas no meio reagente evitam não só a formação de depósitos, decorrentes da desestabilização da emulsão, como também gradientes radiais de temperatura e de concentração.…”