Water-Powered Chemistry Rewrites Rules for Cleaning Up Carbon Monoxide
Scientists have discovered that water enables a completely different chemical pathway for removing carbon monoxide—one that works without oxygen and challenges decades of assumptions about how the reaction occurs. The finding could reshape catalyst design for industrial pollution control and energy applications, with immediate implications for companies developing emissions-cleaning technology.
Originaltitel: A Water-Promoted Mars−van Krevelen Reaction Dominates Low-Temperature CO Oxidation over Au-Fe<sub>2</sub>O<sub>3</sub> but Not over Au-TiO<sub>2</sub>
<p>We provide experimental evidence that is inconsistent with often proposed Langmuir-Hinshelwood (LH) mechanistic hypotheses for water-promoted CO oxidation over Au-Fe2O3. Passing CO and H2O, but no O-2, over Au-gamma-Fe2O3 at 25 degrees C, we observe significant CO2 production, inconsistent with LH mechanistic hypotheses. Experiments with (H2O)-O-18 further show that previous LH mechanistic proposals cannot account for water-promoted CO oxidation over Au-gamma-Fe2O3. Guided by density functional theory, we instead postulate a water-promoted Mars-van Krevelen (w-MvK) reaction. Our proposed w-MvK mechanism is consistent both with observed CO2 production in the absence of O-2 and with CO oxidation in the presence of (H2O)-O-18 and O-16(2). In contrast, for Au-TiO2, our data is consistent with previous LH mechanistic hypotheses.</p>