Beta zeolite as a catalyst for the preparation of alkyl glucoside surfactants: The role of crystal size and hydrophobicity

Zeolite II-beta is an active and selective catalyst for the acetalization of the glucose to form alkyl glucoside nonionic surfactants. The characteristics of size and polarity of reactants, intermediates, and products determine the strong influence of the textural properties of the catalyst (crystal size and adsorption properties) on activity, selectivity, and deactivation. For two series of zeolites with different concentrations of Si-O-Si connectivity defects an optimum in activity is found for intermediate Si/Al ratios, this optimum being reached at lower Si/Al ratios in the series with the lower defect concentration, i.e., in the more hydrophobic series. Thus, the optimum catalyst of the hydrophobic series is more active than that of the hydrophilic series, and it also shows a better resistance to deactivation. (C) 1997 Academic Press.