ALUMINA-SUPPORTED MOLYBDENUM AND TUNGSTEN-OXIDE CATALYSTS - SURFACE-AREA AND PORE-SIZE DISTRIBUTION FROM NITROGEN ADSORPTION AND MERCURY PENETRATION

Surface areas (BET) calculated from nitrogen sorption on aluminum oxid e supports with varying MoO3 and WO3 loadings were consistently higher than surface areas calculated from mercury penetration data. Increasi ng the MoO3 or WO3 content from 0% to about 20% resulted in a gradual decrease in the surface areas calculated from mercury penetration even though the BET surface area remained constant. The mercury contact an gles which provided agreement between BET and mercury penetration surf ace areas decreased with increasing molybdenum or tungsten oxide loadi ng up to the concentration corresponding to about one monolayer covera ge, and approached that of unsupported MoO3 or WO3. The best agreement of data from the two techniques was obtained for samples with pores i n the 100-200 angstrom region.