“Acid-Base site requirements for elimination reactions on alkali promoted MgO”

VERÓNICA K. DÍEZ; CARLOS R. APESTEGUÍA; JUANA I. DI COSIMO

“Studies in Surface Science and Catalysis”

Elsevier

Lugar: Amsterdam; Año: 2000; p. 2219 - 2224

Base-catalyzed elimination reactions were studied on MgO and alkali-modified MgO catalysts using 2-propanol as a probe reactant. The effect of the acid-base properties on the catalyst activity and selectivity was investigated by modifying the surface properties of MgO with 1 mole% of alkaline metals. Group IA metals promote the formation of medium- and high-strength basic sites, thereby increasing the basic site density and strength. The addition of alkaline promoters improves the MgO activity for 2-propanol conversion reactions. The selectivity toward dehydration or dehydrogenation products depends on the base site chemical nature, so that intermediate-strength base sites promote acetone formation whereas highstrength base sites selectively yield propylene. 2-Propanol decomposition to acetone and propylene is proposed to take place via an E1CB mechanism in two parallel pathways sharing a common isopropoxy intermediate.