Role of Isolated Acid Sites and Influence of Pore Diameter in the Low-Temperature Dehydration of Ethanol

Silicoaluminophosphates, SAPO-5 and SAPO-34, differ not only in their pore diameters and structural topology but also in their preferred mechanism of silicon substitution into the framework, which subsequently influences the nature of the acid sites for solid-acid-catalyzed transformations. This study combines <sup>29</sup>Si NMR, FTIR, and DFT calculations for probing the nature of the isolated acid sites, thereby affording structure–property correlations, in the low-temperature catalytic dehydration of ethanol to ethylene.