Highly Selective, Facile
NO<sub>2</sub> Reduction
to NO at Cryogenic Temperatures on Hydrogen Precovered Gold
- Publication date
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Abstract
We have discovered that NO<sub>2</sub> is reduced to
NO at 77 K
by hydrogen precovered gold in vacuum. Here, we investigate the partial
reduction of NO<sub>2</sub> to NO on an atomic-hydrogen populated
model gold catalyst for a more fundamental understanding of the surface
chemistry of hydrogenation. Gold-based catalysts have been found to
be active for many hydrogenation reactions, but few related fundamental
studies have been conducted. Our experimental results reveal a high
catalytic activity for gold: indeed, NO<sub>2</sub> is reduced to
NO with 100% conversion and 100% selectivity at temperatures lower
than 120 K. Density functional theory calculations and reflection–absorption
infrared spectroscopy measurements indicate that HNO<sub>2</sub> and
N<sub>2</sub>O<sub>3</sub> are intermediates which are highly dependent
on surface hydrogen concentrations; subsequent hydrogenation of HNO<sub>2</sub> and dissociation of N<sub>2</sub>O<sub>3</sub> upon annealing
induces the production of NO and H<sub>2</sub>O
