Phosphorus and phosphoric acids induce effects on the physiochemical and catalytic properties of Al-pillared montmorillonite. H 3PO 3 results in a slight increase in the thermal stability and a significant enhancement of total acidity defined as an improvement of Br?nsted acidity and a loss of Lewis acidity. H 3PO 3 causes a strong reduction in the thermal stability, BET area and both Lewis and Br?nsted acid sites. This substantial difference is attributed to different pH and different ease of AlPO 4 formation: low pH and AlPO 4 formation produce deleterious effects. Two different structural models and new acid site formation are proposed. Conversion in the 1-butanol dehydration reaction shows that the conversion is correlated with Lewis acidity. The medium and strong acid sites created explain the ratios of 1-butene (1B) to dibutyl ether (DBE) and of 2-butenes to (1B+DBE). ? 1990.
