Is the W Surface Density of WOx-ZrO2 Catalysts to be Calculated with Respect to the Specific Surface Area of the Sample or That of ZrO2 Only?

The newly developed NO_x-TPD technique provides convincing arguments for the first time upon which calculation of the W surface density is to be done by correcting the surface areas of the catalysts for the contents of WO₃, rather than with the method commonly used in most studies reported to date.