Active Metal Surface Area: PULSE Chemisorption, Temerature Programe Technique and Cyclic Voltammetry

In heterogeneous catalytic reactions, a comparison, hence selection, of catalysts is to be based on intrinsic rates, expressed for example as Turnover Frequencies (TOF). A good measurement of the dispersed active metal surface area (degree of dispersion, Active metal surface area) is important to calculate the turn over frequency (TOF).TOF can be defined as: number of moles of given product/reactant formed/consumed per catalytic site per unit time for the given set of reaction conditions. Values of TOF express intrinsic catalytic ability and hence offer a straightforward means to compare different catalysts and for comparisons of data for the same catalyst prepared by different procedures or characterized in different laboratories. Our aim in this work is to find and compare alternative methods to determine the active metal surface area (AMSA) of noble metal catalysts. For evaluating the active metal surface area of the catalyst, we have used pulse-chemisorption, Temperature program techniques (TPD) and cyclic voltammetry technique (CV). Active surface has been calculated from cyclic voltammtry (CV) using adsorption of H⁺ and Cu²⁺ onto the surface from solutions. The values are compared to each other and also compared with the obtained pulse chemisorptions and TPD values.