The measurement of copper surface areas by reactive frontal chromatography

A technique, termed here “reactive frontal Chromatography,” which permits the evaluation of copper areas in oxide-supported copper catalysts in general is described. The aspect which relates to normal frontal Chromatography is that of the flow switching technique, flows being changed from helium to a helium/nitrous oxide mixture. In this case, however, instead of simply observing the N 2O uptake as in normal frontal Chromatography, the N 2O decomposes upon adsorption yielding N 2 in the gas phase, the oxygen being chemisorbed on the surface: this is the reactive aspect. Therefore before the N 2O breakthrough occurs, N 2 is evolved in an amount equivalent to the number of oxygen atoms chemisorbed on the copper surface. The technique has been calibrated against a sample of unsupported copper whose area is determined in the same apparatus by the BET method.