Preparation, characterization and NMR spectra of platinum on alumina catalysts in relation to their activity and stability

Abstract

Two alumina-supported platinum catalysts were prepared to give a high and a low dispersion. They were characterised by four different techniques: hydrogen adsorption, hydrogen-oxygen titration, electron microscopy and 195Pt nuclear magnetic resonance. Agreement between the two latter methods was quantitative, but only satisfactory with the titration technique. NMR line shapes clearly showed the ‘surface’ and ‘bulk’ peaks. The structure-sensitive methylcyclopentane hydrogenolysis reaction was used to confirm, in a micropulse reactor, the respective catalyst dispersions. The utility of the high-dispersion catalyst was demonstrated in a microcontinuous reactor with a severe dehydrogenation stability test.