Relation between adsorption and catalysis in the case of NiO and Co 3O 4

Abstract

Reversed flow-inverse gas chromatography is a quick, precise and effective methodology to characterize physicochemical properties of adsorbents. This is extended to the experimental measurement of the adsorption energy distribution function as well as of the differential energy of adsorption due to lateral interactions of molecules adsorbed on two catalysts, namely Co 3O 4 and NiO. Thus, the nature and the strength of the adsorbate–adsorbent and adsorbate–adsorbate interactions are extracted in order to give detailed answers to the questions: (a) where are the molecules on the heterogeneous surface and (b) which is the nature of the surface chemical bonds? Thus, adsorption of 1-butene was found to take place immediately and irreversibly. It holds a deep relation between adsorption and catalysis of 1-butene over these catalysts. As a consequence, the adsorption of 1-butene in the presence of hydrogen leads to isobutane and/or n-butane, depending on the temperature. It can be seen from the adsorption/desorption kinetic constants that the adsorption of 1-butene on Co 3O 4 is one order higher than over NiO. This fact in connection with the bigger activation energy and the lower kinetic coefficients concerning hydrogenation reaction over NiO shows that Co 3O 4 is a better catalyst for this kind of catalysis.