Zeolite NaY-supported gold complexes prepared from Au(CH3)2(C5H7O2): reactivity with carbon monoxide

Abstract

Mononuclear gold complexes in zeolite NaY were synthesized from initially physisorbed Au(CH 3 ) 2 (C 5 H 7 O 2 ), and their reactions with CO in a flow system at 298 K and 760 Torr were investigated by infrared (IR) spectroscopy and mass spectral analysis of the effluent gases. CH 4 and CO 2 were formed as CO flowed through the sample either steadily or as successive pulses. The results are consistent with the inferences that (a) CO reacted with the supported gold to form gold carbonyls, (b) CH 4 formed by reaction of methyl groups on gold with traces of H 2 O or hydroxyl groups on the zeolite and (c) CO on cationic gold reacted with traces of O 2 and/or H 2 O to form CO 2 . In samples treated in steadily flowing CO, cationic gold was reduced to zerovalent gold, but the cationic gold in samples exposed to CO pulses was not reduced to zerovalent gold, although CO 2 formed. Thus, CO adsorbed on cationic gold reacts to give CO 2 in the absence of zerovalent gold, consistent with the inference that gold catalysts for CO oxidation need not contain zerovalent gold.

Insights into the reactivity of supported Au nanoparticles: combining theory and experiments

“…This includes transfer of activated oxygen from the support (i.e., reducible or irreducible support), or special active sites at the metal/oxide boundary [8,[54][55][56][57][58][59][60][61][62][63][64]. Finally, there are a number of reports of catalysts consisting of single or a few Au + ions in the support [27,[65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81]. We note that combinations of the above effects can come into play; the gold-support interaction may for instance determine the morphology of the gold particles and thus influence the number of low-coordinated atoms or the strain.…”

The Best of Two Worlds from the Gold Catalysis Universe: Making Homogeneous Heterogeneous

“…Another important conclusion of the same study was that the type of CO stream can influence the change in the gold oxidation state: If CO is added in pulses, gold remained unreduced (Au III ), but in steadily flowing CO, the reduction of cationic gold (Au III ) to zero valent gold (Au 0 ) was observed. [45] In both cases, CO 2 was formed.…”

“…[ 45] In another work of Fierro-Gonzalez et al, [45] the NaY zeolite was also used and it was demonstrated that the initial CH 3 ligands from the CAu0 complex can be released during the reaction. Steadily flowing or pulsed CO reacted in the active Au site, which produces CO 2 and CH 4 , the latter probably being formed by the reaction of CH 3 groups, linked to the Au atom with H 2 O in the stream.…”

Two Gold Surfaces and a Cluster with Remarkable Reactivity for CO Oxidation, a Density Functional Theory Study

“…and catalysis since Haruta et al reported their remarkably high activity for low temperature CO oxidation [1]. Since this breakthrough, the reaction has been studied extensively, on supported particles [2][3][4][5], atomically dispersed species [6,7], and Surf. Sci.…”