Water Influences the Activity and Selectivity of Ceria-Supported Gold Catalysts for Oxidative Dehydrogenation and Esterification of Ethanol

Abstract

In this study, we show that water influences the activity and selectivity of a ceria-supported gold catalyst for the oxidative dehydrogenation and esterification of ethanol in a fixedbed flow reactor, resulting in the production of acetaldehyde and ethyl acetate, respectively. The rate of acetaldehyde formation was enhanced upon incorporation of water in the feed stream at low pressures; beyond this, the water had little effect on the kinetics of the primary oxidation reaction. However, water induced significant changes to ethyl acetate production, decreasing the reaction order in ethanol and slowing the reaction rate. Furthermore, a large kinetic isotope effect for esterification was observed upon incorporation of either D 2 O or d-ethanol in the system, suggesting that breaking an OH bond is associated with the rate-determining step for this reaction. Our observations are consistent with the esterification process occurring through secondary oxidation of acetaldehyde to acetate species on the ceria surface followed by the acid-catalyzed esterification of surface acetates with ethanol. These results highlight the importance of water in gold-catalyzed processes and show that water can direct reaction selectivity in addition to influencing activity (as many previous studies have shown for CO oxidation).

Engineered nanomaterials: From their properties and applications, to their toxicity towards marine bivalves in a changing environment

“…CeO 2 NPs are also used as glass polishers, as purifiers of Mischmetal, and in heat-resistant coatings (EPA, 2009) and exploited for their antibacterial properties (Jeong et al, 2005;Lee et al, 2005;Shrivastava et al, 2007). Moreover, it can be used as a catalyst itself or as a support, treatment of toxic gases and pollutants, solid oxide fuel cells, oxygen sensors, and biomedicine (Abbott et al, 2010;Amrute et al, 2012;Vile et al, 2012;Chang et al, 2013;Mann et al, 2014;Yao et al, 2014;Mullen et al, 2017). Pristine Ceria has been successfully used in alkyne semi hydrogenation reactions (Camellone et al, 2016) with high activity and selectivity to the alkene products.…”

Breaking H2 with CeO2: Effect of Surface Termination

“…Ceria has attracted much attention in the last years because of its numerous technological application fields such as heterogeneous catalysis, 1,2 where it can be used as a catalyst itself 3−6 or as a support, 7−13 treatment of toxic gases and pollutants, 14,15 solid oxide fuel cells, 16,17 oxygen sensors, 18−20 and biomedicine. 21,22 Pure ceria has been successfully used in alkyne semihydrogenation reactions 5,23−25 with high activity and selectivity to the alkene products.…”

Structure‐Activity Relationships of Au/Al2O3 Catalyst for the Selective Oxidative Esterification of 1,3‐Propanediol and Methanol

“…Recently, an environmentally benign one‐pot route in the presence of supported Au catalyst has attracted great attention instead of the two‐step route to produce methyl esters from alcohols or aldehydes . The Au−Pd/Al 2 O 3 and Au/TiO 2 show higher selectivity of methyl 3‐hydroxypropionate (with the selectivity of 85%) from 1,3‐propanediol.…”