Sulfonated latex particle as acid catalysts for the continuous inversion of sucrose

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Abstract
Sulfonated polystyrene latex particles were used as acid catalysts in the continuous inversion of sucrose at 50–70°C. The particles (surface charge 168 μeq/g) were confined in a stirred reactor with a semipermeable membrane; sucrose solution was pumped in, and product solution was pumped out. The catalytic activity of the particles was unchanged after 20 days continuous use. Variation of particle size (0.13 and 0.42 μm) and stirring rate showed that internal and external mass transfer was not a controlling factor. The kinetics were pseudo‐first‐order; the rate constant at 70°C was 2.30/N min as compared with 0.07/N min for macroporous sulfonated ion‐exchange resin; the apparent activation energy was 111 kJ/mol as compared with 121 kJ/mol for the homogeneous acid‐catalyzed reaction. The faster rate was attributed to the very great surface area, high charge density, and lack of internal diffusional resistance of the latex particles. The proposed mechanism comprised adsorption of sucrose on the particle surface, followed by inversion and desorption of product.