Development of a Continuous Emulsion Copolymerization Process in a Tubular Reactor

Abstract

This contribution describes the development of a continuous emulsion copolymerization processs for vinyl acetate and n-butyl acrylate in a tubular reactor. Special features of this reactor include the use of oscillatory (pulsed) flow and internals (sieve plates) to prevent polymer fouling and promote good radial mixing, along with a controlled amount of axial mixing. The copolymer system studied (vinyl acetate and butyl acrylate) is strongly prone to composition drift due to very different reactivity ratios. An axially dispersed plug flow model, based on classical free radical copolymerization kinetics, was developed for this process and used successfully to optimize the lateral feeding profile to reduce compositional drift. An energy balance was included in the model equations to predict the effect of temperature variations on the process. The model predictions were validated with experimental data for monomer conversion, copolymer composition, average particle size, and temperature measured along the reactor length.

In‐Line Monitoring of Particle Size during Emulsion Polymerization under Different Operational Conditions using NIR Spectroscopy

“…The run‐to‐run variability in the PSPC column can be observed in Figure 7, by comparing the off‐line measurements of monomer conversion (by gravimetry) and average particle size (by DLS) in a series of different runs of VAc‐BuA copolymerization carried out in the PSCP tubular reactor in steady‐state, using similar conditions of recipe and operating conditions. This plot includes data from the runs reported in Figure 6 and from additional reactions reported in our previous works 33, 34. The overall run‐to‐run reproducibility for conversion was ±0.05 and for average particle size measured by DLS was ±10 nm.…”

Process Model for Styrene and n-Butyl Acrylate Emulsion Copolymerization in Smart-Scale Tubular Reactor

“…Also, the estimated constant value of U = 73.96 W m −2 K −1 is close to a value (also constant) measured for the emulsion polymerization in a different tubular reactor. 9 As will be discussed in section 4.5, the knowledge of the heat transfer coefficient U in the enthalpy balance enables the online estimation of the number concentration of particles in the reaction mixture N T . Table 4 presents the comparison of measured and predicted particle sizes d p and the predicted number concentration of particles N T , while Figure 8 displays the evolution of particle sizes along the reactor for the various Sty/BA ratios.…”

“…The focus is kept on developing a rationally reduced model in order to simulate the process trajectory in a short time, thus enabling its incorporation into model-based predictive control. Regrettably, only a handful of experimental , and/or modeling − studies is published in the open literature regarding the process intensification of emulsion copolymerization in tubular reactors. Paquet and Ray , developed and validated a general model of emulsion polymerization in tubular reactors, which can be used for scale-up design studies.…”

“…The developed model was also used to test different start-up procedures and reaction temperatures. Later, they adapted the model also for the optimization of vinyl acetate/ n -butyl acrylate emulsion copolymerization in a tubular reactor . To study the evolution of polymer particle size distribution during the reaction, Bouaswaig et al implemented the population balance equation into the model developed by Sayer et al As only a decent agreement with experimental data has been obtained, the authors suggested that including the dependence of monomer concentration in polymer particles on the particle size might significantly improve the results.…”

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.…”