STUDY OF PHOSPHORUS-MODIFIED ALUMINUM PILLARED MONTMORILLONITE .1. EFFECT OF THE NATURE OF PHOSPHORUS-COMPOUNDS

Phosphorus and phosphoric acids induce effects on the physiochemical and catalytic properties of Al-pillared montmorillonite. H3PO3 results in a slight increase in the thermal stability and a significant enhancement of total acidity defined as an improvement of Br-theta-nsted acidity and a loss of Lewis acidity. H3PO4 causes a strong reduction in the thermal stability, BET area and both Lewis and Br-theta-nsted acid sites. This substantial difference is attributed to different pH and different ease of AlPO4 formation: low pH and AlPO4 formation produce deleterious effects. Two different structural models and new acid site formation are proposed. Conversion in the 1 butanol 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).