Adsorption of sucrose on zeolites

Abstract

The adsorption of sucrose on FAU type zeolites was measured depending on the ratio of Si/Al and the solvent composition (ethanol–water). The maximal loading was found to be 1 sucrose molecule per α-cage. The adsorption can proceed from water on strong dealuminated zeolites and from an ethanol water mixture on aluminum rich zeolites. To recover sucrose the zeolite can be treated with ethanol–water. Alternatively the liquid is first mixed with an alcohol, sucrose is adsorbed on a hydrophilic zeolite and desorbed by the addition of water. An application is reported for the desugarization of sugar-beet molasses and process liquids of a beet sugar factory. The adsorption obeys the Langmuir isotherm and is selective compared with other saccharides. The effective diffusion coefficient of sucrose inside the zeolite pores was measured.