On the Role of Water in Heterogeneous Catalysis: A Tribute to Professor M. Wyn Roberts

Abstract

From the earliest studies of heterogeneous catalysis, it was apparent that water plays a more important role in many systems than simply acting as a solvent. Its wide ranging effects have attracted increasing attention in recent years and was the topic of Prof. M.W. Roberts' final paper. The present review explores some of the latest work on water in reactions ranging from CO oxidation to Fischer-Tropsch catalysis, the different mechanisms proposed for its role are discussed and compared.

Insights into Functionality-Specific Adsorption Dynamics and Stable Reaction Intermediates Using Fast Field Cycling NMR

“…We suggest that this FFC-NMR methodology can be generalised to the understanding of any competitive adsorption process, such as catalyst poisoning and water promotion effects which are of great importance in the field of heterogeneous catalysis. 45,46 Supporting information 1 H and 13 C spectra of acetone adsorbed on γ-alumina…”

Avoiding Self‐Poisoning: A Key Feature for the High Activity of Au/Mg(OH)2 Catalysts in Continuous Low‐Temperature CO Oxidation

“…Finally,itshould be mentioned that the above conclusions were reached and are valid under dry reaction conditions, with no further insertion of water during the CO oxidation as moisture filters were used for all gases.I ti sw ell known that the presence of water in the reaction atmosphere/on the catalyst surface may significantly change the reaction characteristics and even the dominant reaction pathway. [14][15][16][17] On Au/TiO 2 at room temperature,for example,awater-mediated reaction mechanism with av ery low energy barrier for O 2 activation was shown to dominate the CO oxidation in the presence of adsorbed water. [15] Additionally,t he presence of water may also affect the catalyst stability,m ost likely by water-assisted decomposition of reaction-inhibiting surface carbonate species.…”

“…[14][15][16][17] On Au/TiO 2 at room temperature,for example,awater-mediated reaction mechanism with av ery low energy barrier for O 2 activation was shown to dominate the CO oxidation in the presence of adsorbed water. [14][15][16][17] On Au/TiO 2 at room temperature,for example,awater-mediated reaction mechanism with av ery low energy barrier for O 2 activation was shown to dominate the CO oxidation in the presence of adsorbed water.…”

Vermeiden von Selbstvergiftung – ein Schlüsselaspekt für die hohe Aktivität von Au/Mg(OH)2‐Katalysatoren in der kontinuierlichen Niedertemperatur‐CO‐Oxidation

“…[14][15][16][17] So wurde fürd ie Raumtemperatur-CO-Oxidation auf Au/ TiO 2 gezeigt, dass diese in Gegenwart von adsorbiertem Wasser hauptsächlich über einen Wasser-gestützten Reaktionsmechanismus mit einer sehr niedrigen Barriere fürdie O 2 -Aktivierung verläuft. Es ist bekannt, dass Wasserdampf in der Reaktionsatmosphäre/auf der Katalysatoroberfläche den Ablauf der Reaktion und den dominierenden Reaktionspfad deutlich verändern kann.…”

“…Es ist bekannt, dass Wasserdampf in der Reaktionsatmosphäre/auf der Katalysatoroberfläche den Ablauf der Reaktion und den dominierenden Reaktionspfad deutlich verändern kann. [14][15][16][17] So wurde fürd ie Raumtemperatur-CO-Oxidation auf Au/ TiO 2 gezeigt, dass diese in Gegenwart von adsorbiertem Wasser hauptsächlich über einen Wasser-gestützten Reaktionsmechanismus mit einer sehr niedrigen Barriere fürdie O 2 -Aktivierung verläuft. [15] Außerdem kann die Gegenwart von Wasser auch die Stabilitätd es Katalysators beeinflussen, vermutlich über eine Wasser-induzierte Zersetzung von reaktionsinhibierenden Oberflächencarbonaten.…”