Synthesis and characterization of ZrO2 as acid-basic catalysts: Reactivityof 2-methyl-3-butyn-2-ol

Two ZrO2-based catalysts have been synthesized by thermal treatment of a ge l prepared from ZrOCl2 . 8H(2)O. The effect of different preparation parame ters on the final properties of the solids was studied. Textural characteri zation was carried out from nitrogen adsorption/desorption isotherms. XRD a nd FT-Raman spectroscopy have been used to elucidate the physical state of the catalysts. Their acid-base properties were studied following temperatur e programmed desorption-mass spectrometry and diffuse reflectance infrared Fourier transform techniques, by using pyridine, 2,6-dimethylpyridine and c arbon dioxide as probe molecules. Both solids were tested for the 2-methyl- 3-butyn-2-ol reaction by using two different procedures: (a) in a microcata lytic pulse reactor and (b) through isotherm and temperature programmed sur face reactions in a how reactor. In addition, temperature programmed oxidat ion and temperature programmed desorption experiments revealed that catalys t deactivation was caused by carbon deposition on the catalytic surface. Am photeric selectivity for both solids, leading to 3-hydroxy-3-methyl-2-butan one and 3-methyl-3-buten-2-one, depends on the reaction temperature; thus, it is 92% at 225 degrees C for a catalyst calcined at 400 degrees C (ZrO2-4 00VAC). (C) 1999 Academic Press.