Adsorption-desorption and catalytic properties of SBA-15 supported cesium salts of 12-molybdophosphoric acid for the dehydration of ethanol

Abstract

Cesium salts of molybdophosphoric acid with varying amounts of the cations Cs1H2PMo12O40 and Cs3PMo12O40 have been prepared as pure or supported on SBA-15. The adsorption of ethanol and its temperature programmed desorption-TPD using thermogravimetry were studied for SBA-15 supported and unsupported Cs salts. The evolved gases during the adsorption-desorption of ethanol on CsHPM/SBA-15 composites were identified by online mass spectrometry coupled with thermogravimetry. The main products observed in the evolved gases during the desorption of ethanol were C2H4, C3H6 and unreacted ethanol. The amount of acidic sites of the composites was estimated by ammonia adsorption-desorption. The dehydration of ethanol was used to test the catalytic properties of the CsHPM samples incorporated on the silica matrix. SBA15 - supported catalysts, appeared to be more active than bulk catalysts in vapor phase dehydration and dehydrogenation of ethanol reactions. The effect of the support leads to higher values of dehydration rates of ethanol as well as higher values of ethylene and acetaldehyde formation rates.