Active-Site Coating for Molecular Discrimination in Heterogeneous Catalysis

Abstract

A coherent layer of zeolite A has been applied to a SiO₂-supported Pt−Fe oxidation catalyst, using total surface charge-reversal. The zeolite has tracked the metals into the pore structure of the support, covering the active sites. The zeolite channel size is large enough to allow access of CO and O₂ to the active sites, and to allow CO₂ to emerge, but it excludes larger molecules. The presence of the zeolite membrane transforms the supported Pt−Fe into a highly specific catalyst, which can discriminate between CO and butane, even after the macroscopic catalyst particles are crushed.