Spectroscopic characterization and catalytic activity of zeolite X containing occluded alkali species

Samples of zeolite X containing occluded cesium oxide (prepared via decomposition of impregnated cesium acetate) and occluded alkali metal (prepared via decomposition of impregnated alkali azide) were synthesized, characterized, and tested as solid base catalysts. X-Ray absorption spectroscopy at the Cs L-III edge was used to probe the local structure in zeolites containing exchangeable cesium cations and occluded cesium oxides. Since the Cs-O interatomic distances determined by EXAFS were similar in both the zeolites and reference compounds, the white line intensity was proposed to correlate with ionicity of the Cs-O bond. Infrared spectroscopy of adsorbed carbon dioxide and temperature-programmed desorption of CO2 confirmed that occlusion of cesium oxide in the zeolite pores created new strong base sites that were catalytically active in the decomposition of 2-propanol to acetone. Alkali metal-loaded zeolites were found to be catalysts for the side-chain alkenylation of o-xylene with 1,3-butadiene to form 5-o-tolyl-2-pentene. Results from ESR spectroscopy suggested that extralattice alkali metal clusters contribute to the formation of active species for alkenylation. (C) 1999 Academic Press.