Nanoporous Gold Catalysts for Selective Gas-Phase Oxidative Coupling of Methanol at Low Temperature

TLDR

Gold catalysis is limited by low O₂ dissociation, but Au nanoparticles on oxides can overcome this, though they tend to sinter. The study aims to develop nanoporous Au, prepared by dealloying AuAg alloys, as a stable, support‑free catalyst. Nanoporous Au is produced by dealloying AuAg alloys, yielding a stable, support‑free structure. The catalyst achieves >97 % selectivity to methyl formate with high turnover frequencies below 80 °C, demonstrating that Au surface chemistry remains unchanged while O₂ activation is enhanced, and that residual silver controls reactive oxygen availability.

Abstract

Gold (Au) is an interesting catalytic material because of its ability to catalyze reactions, such as partial oxidations, with high selectivities at low temperatures; but limitations arise from the low O2 dissociation probability on Au. This problem can be overcome by using Au nanoparticles supported on suitable oxides which, however, are prone to sintering. Nanoporous Au, prepared by the dealloying of AuAg alloys, is a new catalyst with a stable structure that is active without any support. It catalyzes the selective oxidative coupling of methanol to methyl formate with selectivities above 97% and high turnover frequencies at temperatures below 80 degrees C. Because the overall catalytic characteristics of nanoporous Au are in agreement with studies on Au single crystals, we deduced that the selective surface chemistry of Au is unaltered but that O2 can be readily activated with this material. Residual silver is shown to regulate the availability of reactive oxygen.