Selectivity Control in Gold‐Mediated Esterification of Methanol

Xu, Bingjun; Li, Xiaoying; Haubrich, Jan; Madix, Robert J.; Friend, Cynthia M.

doi:10.1002/anie.200805404

Cited by 174 publications

(306 citation statements)

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“…1a). Where comparable studies have been performed, the reactivity of O-covered Au(110)-(1x2) [23] and Au(111) [19] are similar. Likewise, the temperatures for O recombination to O 2 are similar for the (111) [24,25] and (110) [26] surfaces.…”

Section: Introductionmentioning

confidence: 61%

“…[17] In addition, the activity and selectivity for O-assisted methanol coupling on O-covered Au(111) depends on O coverage-higher activity and selectivity are observed for low O coverages. [19] Herein, we investigate the bonding of O on Au(110) in order to better exploit atomic-scale imaging using STM in conjunction with DFT studies. The Au(110) surface reconstructs to the missing-row Au(110)-(1x2) structure, which consists of an ordered array of (111) microfacets [20][21][22] capped by rows of atoms with low coordination number along the [1][2][3][4][5][6][7][8][9][10] direction (Fig.…”

Section: Introductionmentioning

confidence: 99%

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Direct visualization of quasi-ordered oxygen chain structures on Au(110)-(1 × 2)

et al. 2016

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The Au(110) surface offers unique advantages for atomically-resolved model studies of catalytic oxidation processes on gold. We investigate the adsorption of oxygen on Au(110) using a combination of scanning tunneling microscopy (STM) and density functional theory (DFT) methods. We identify the typical (empty-states) STM contrast resulting from adsorbed oxygen as atomic-sized dark features of electronic origin. DFT-based image simulations confirm that chemisorbed oxygen is generally detected indirectly, from the binding-induced electronic structure modification of gold. STM images show that adsorption occurs without affecting the general structure of the pristine Au(110) missing-row reconstruction. The tendency to form onedimensional structures is observed already at low coverage (<0.05ML), with oxygen adsorbing on alternate sides of the reconstruction ridges. Consistently, calculations yield preferred adsorption on the (111) facets of the reconstruction, on a 3-fold coordination site, with increased stability when adsorbed in chains. Gold atoms with two oxygen neighbors exhibit enhanced electronic hybridization with the O states. Finally, the species observed are reactive to CO oxidation at 200K and desorption of CO 2 leaves a clean and ordered gold surface.2

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Section: Introductionmentioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Direct visualization of quasi-ordered oxygen chain structures on Au(110)-(1 × 2)

et al. 2016

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“…Gold nanoparticles on porous SiO 2 (SiO 2 -Au) led to mainly MF production, which is in accordance with the literature on Au catalysts. 46,47 Moreover, dimethyl ether selectivity was not observed in this case.…”

Section: Methanol Aerobic Transformation Over Au-loaded Catalysts Thmentioning

confidence: 68%

Investigating the Influence of Au Nanoparticles on Porous SiO₂–WO₃ and WO₃ Methanol Transformation Catalysts

et al. 2016

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American Chemical SocietyDepuccio, DP.; Ruiz-Rodríguez, L.; Rodriguez-Castellon, E.; Botella Asuncion, P.; López Nieto, JM.; Landry, CC. (2016) AbstractAnalyzing the structural and chemical properties of materials at the interface of metal nanoparticles and metal oxide supports is important for catalytic applications. Tungsten oxide (WO 3 ) is a widely studied catalyst, but changing the catalytic reactivity at the surface of this oxide with metal nanoparticles is of interest. In this work, we sought to modify the redox properties of porous WO 3 and SiO 2 -WO 3 catalysts with sonochemically deposited gold nanoparticles (Au NPs) in order to access and study this reaction pathway. Characterization using powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), and inductively-coupled plasma optical emission spectroscopy (ICP-OES) confirmed that crystalline Au NPs with diameters of 5 -12 nm were distributed throughout the catalysts. Temperature-programmed desorption (TPD) was used to probe the surface acidity of the catalysts. The physic-chemical characteristics of catalysts have been also discussed by considering the catalytic performance of these materials in the aerobic transformation of methanol. Catalysts containing nanocrystalline WO 3 but no Au NPs displayed very high selectivity to DME (> 60%) at all conversions with minor oxidation reactivity, which highlighted the acidic nature of these catalysts. No effect on the acidity of the catalysts was observed by TPD when Au NPs were loaded in the catalysts. The reducibility of the crystalline WO 3 species, however, increased significantly due to the interaction with Au NPs, as observed by temperature-programmed reduction (TPR). In the gas-phase transformation of MeOH under aerobic conditions, catalysts modified with Au NPs showed greater activity compared to non-modified catalysts. In addition, oxidation selectivity to products such as methyl formate as well as formaldehyde, dimethoxymethane, and carbon oxides became heavily favored with only minor dehydration selectivity. The redox properties of these WO 3 catalysts could be tuned by changing the Au loading. More labile lattice oxygen and enhanced redox properties at the surface of WO 3 modified with Au NPs clearly altered these traditional dehydration catalysts to potential oxidation catalysts. Thus, modification of WO 3 with Au is an effective way to expand the MeOH transformation product distribution beyond DME to other useful, oxidized products not typically observed over pure WO 3 .

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“…It has been demonstrated that oxygenprecovered gold flat surfaces are reactive toward water, [32] carbon monoxide [38] carbon dioxide [50,51], acetylene [52], ammonia [39], amines [53], methanol [52], and alcohols [54][55][56]. Limitations in the partial oxidation reactions catalyzed on gold surfaces [22,23,42,43,53,[57][58][59][60][61][62][63][64][65][66] are related to the low O 2 dissociation rate [42]. The dissociation probability for O 2 on single-crystal Au surfaces has been found to be extremely small [<<10 -6 as reported in Ref.…”

Section: Introductionmentioning

confidence: 99%

“…47]. To overcome the high dissociation barrier [67,68] for O 2 , different methods have been used for stabilizing oxygen atoms on gold (atomic O sources [69], thermal dissociation [70], oxygen-ion sputtering [71], microwave discharge [72], electron bombardment of physisorbed layers of oxygen [73,74] and the usage of reactive molecules such as NO 2 [60] or O 3 [57,59,75,76]). …”

Section: Introductionmentioning

confidence: 99%

O2 dissociation in Na-modified gold ultrathin layer on Cu(111)

Politanoa

Chiarello

2010

Gold Bull

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High-resolution electron energy loss spectroscopy has been used to investigate the catalytic properties of Na-doped Au monolayer grown on Cu(111). The presence of Na atoms allows the dissociation of oxygen molecules and the stabilization of atomic oxygen. The strong reduction of the dissociation barrier for O 2 promoted by Na could readily favor many surface chemical reactions, due to the key role of atomic oxygen in many oxidation processes catalyzed by gold.

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Selectivity Control in Gold‐Mediated Esterification of Methanol

Cited by 174 publications

References 29 publications

Direct visualization of quasi-ordered oxygen chain structures on Au(110)-(1 × 2)

Direct visualization of quasi-ordered oxygen chain structures on Au(110)-(1 × 2)

Investigating the Influence of Au Nanoparticles on Porous SiO₂–WO₃ and WO₃ Methanol Transformation Catalysts

O2 dissociation in Na-modified gold ultrathin layer on Cu(111)

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Selectivity Control in Gold‐Mediated Esterification of Methanol

Cited by 174 publications

References 29 publications

Direct visualization of quasi-ordered oxygen chain structures on Au(110)-(1 × 2)

Direct visualization of quasi-ordered oxygen chain structures on Au(110)-(1 × 2)

Investigating the Influence of Au Nanoparticles on Porous SiO2–WO3 and WO3 Methanol Transformation Catalysts

O2 dissociation in Na-modified gold ultrathin layer on Cu(111)

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Investigating the Influence of Au Nanoparticles on Porous SiO₂–WO₃ and WO₃ Methanol Transformation Catalysts