scholarly journals Controlled Metal–Support Interactions in Au/CeO2–Mg(OH)2 Catalysts Activating the Direct Oxidative Esterification of Methacrolein with Methanol to Methyl Methacrylate

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3146
Author(s):  
Nagyeong Kim ◽  
Seulgi Lim ◽  
Seungdon Kwon ◽  
Yuyeol Choi ◽  
Ji-Woong Lee ◽  
...  
Keyword(s):  
Methyl Methacrylate ◽  
Calcination Temperature ◽  
Au Nanoparticle ◽  
X Ray ◽  
Oxidative Esterification ◽  
Composition Ratio ◽  
Relative Composition ◽  
Metal Support ◽  
Metal Support Interactions ◽  
Three Components

The strong metal–support interaction (SMSI) between the three components in Au/CeO2–Mg(OH)2 can be controlled by the relative composition of CeO2 and Mg(OH)2 and by the calcination temperature for the direct oxidative esterification of methacrolein (MACR) with methanol to methyl methacrylate (MMA). The composition ratio of CeO2 and Mg(OH)2 in the catalyst affects the catalytic performance dramatically. An Au/CeO2 catalyst without Mg(OH)2 esterified MACR to a hemiacetal species without MMA production, which confirmed that Mg(OH)2 is a prerequisite for successful oxidative esterification. When Au/Mg(OH)2 was used without CeO2, the direct oxidative esterification of MACR was successful and produced MMA, the desired product. However, the MMA selectivity was much lower (72.5%) than that with Au/CeO2–Mg(OH)2 catalysts, which have an MMA selectivity of 93.9–99.8%, depending on the relative composition of CeO2 and Mg(OH)2. In addition, depending on the calcination temperature, the crystallinity of the CeO2–Mg(OH)2 and the surface acidity/basicity can be remarkably changed. Consequently, the Au-nanoparticle-supported catalysts exhibited different MACR conversions and MMA selectivities. The catalytic behavior can be explained by the different metal–support interactions between the three components depending on the composition ratio of CeO2 and Mg(OH)2 and the calcination temperature. These differences were evidenced by X-ray diffraction, X-ray photoelectron spectroscopy, and CO2 temperature-programmed desorption. The present study provides new insights into the design of SMSI-induced supported metal catalysts for the development of multifunctional heterogeneous catalysts.

Strong metal–support interactions in Pd/Co3O4 catalyst in wet methane combustion: in situ X-ray absorption study

2020 ◽  
Vol 10 (13) ◽  
pp. 4229-4236
Author(s):  
William Barrett ◽  
Somaye Nasr ◽  
Jing Shen ◽  
Yongfeng Hu ◽  
Robert E. Hayes ◽  
...  
Keyword(s):  
Methane Combustion ◽  
Absorption Study ◽  
X Ray ◽  
Metal Support ◽  
Metal Support Interactions ◽  
X Ray Absorption

CoOx inhibits Pd oxidation in CH4 combustion in the wet feed.

scholarly journals Capturing metal-support interactions in situ during the reduction of a Re promoted Co/γ-Al2O3 catalyst

2016 ◽  
Vol 52 (15) ◽  
pp. 3239-3242 ◽  
Author(s):  
N. E. Tsakoumis ◽  
R. E. Johnsen ◽  
W. van Beek ◽  
M. Rønning ◽  
E. Rytter ◽  
...  
Keyword(s):  
Crystal Lattice ◽  
Powder Diffraction ◽  
X Ray ◽  
Metal Support ◽  
Metal Support Interactions ◽  
Al2o3 Catalyst

The diffusion of Co2+ cations into the γ-Al2O3 support is probed during the reduction of a Re/Co/γ-Al2O3 catalyst by in situ by synchrotron X-ray powder diffraction resulting in the expansion of its crystal lattice.

scholarly journals Synthesis and Characterization of Pd over Novel TiO2 Mixtures: Insights on Metal–Support Interactions

2020 ◽  
Vol 2 (1) ◽  
pp. 13
Author(s):  
Matías G. Rinaudo ◽  
Ana M. Beltrán ◽  
María A. Fernández ◽  
Luis E. Cadús ◽  
Maria R. Morales
Keyword(s):  
Photoelectron Spectroscopy ◽  
Anatase Phase ◽  
High Energy ◽  
Atomic Ratio ◽  
Oxidation Reactions ◽  
X Ray ◽  
Surface Areas ◽  
Scanning Transmission ◽  
Metal Support ◽  
Metal Support Interactions

Palladium nanoparticles were supported on unusual mixtures of anatase, TiO2 (II) and rutile titania phases by wet impregnation, obtaining catalysts with metal contents of ca. 0.25 wt % labeled Pd/Ti5, Pd/Ti45, and Pd/Ti120. Crystalline structures were confirmed by X-ray diffraction. Pd particle sizes in the range of 4–20 nm were observed by scanning-transmission electron Microscopy. External surface areas (SBET) in the range 10–17 m2 g−1 were higher enough to achieve a good distribution of palladium over titanium oxide outer surface, as evidenced by energy-dispersive X-ray spectroscopy elemental profiles. Pd0/Pdδ+ atomic ratio measured by X-ray photoelectron spectroscopy showed a decrease from Pd/Ti5 to Pd/Ti120, in line with the decrease in anatase phase present in the catalysts. This behavior suggested that palladium tended to form more TiPdxO structures in Pd/Ti5 whilst PdOx structures were more likely to be present on supports with greater amounts of TiO2 (II) and rutile, due to the distinct metal–support interactions. An increase in reducibility and oxygen mobility from Pd/Ti5 to Pd/Ti120 was observed by temperature programmed measurements and associated to the different high-energy ball milled supports. Catalysts with improved properties reported herein could exhibit an excellent performance in oxidation reactions, e.g., glycerol selective oxidation.

scholarly journals A Multifunctional Au/CeO2-Mg(OH)2 Catalyst for One-Pot Aerobic Oxidative Esterification of Aldehydes with Alcohols to Alkyl Esters

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1536
Author(s):  
Seulgi Lim ◽  
Seungdon Kwon ◽  
Nagyeong Kim ◽  
Kyungsu Na
Keyword(s):  
Methyl Methacrylate ◽  
Heterogeneous Catalysts ◽  
Au Nanoparticles ◽  
Alkyl Esters ◽  
One Pot ◽  
Oxidative Esterification ◽  
Highly Active ◽  
Metal Support Interaction ◽  
Metal Support ◽  
Supported Metal Nanoparticles

Au nanoparticles bound to crystalline CeO2 nanograins that were dispersed on the nanoplate-like Mg(OH)2, denoted as Au/CeO2-Mg(OH)2, were developed as the highly active and selective multifunctional heterogeneous catalyst for direct oxidative esterification of aldehydes with alcohols to produce alkyl esters under base-free aerobic conditions using oxygen or air as the green oxidants. Au/CeO2-Mg(OH)2 converted 93.3% of methacrylaldehyde (MACR) to methyl methacrylate (MMA, monomer of poly(methyl methacrylate)) with 98.2% selectivity within 1 h, and was repeatedly used over eight recycle runs without regeneration. The catalyst was extensively applied to other aldehydes and alcohols to produce desirable alkyl esters. Comprehensive characterization analyses revealed that the strong metal–support interaction (SMSI) among the three catalytic components (Au, CeO2, and Mg(OH)2), and the proximity and strong contact between Au/CeO2 and the Mg(OH)2 surface were prominent factors that accelerated the reaction toward a desirable oxidative esterification pathway. During the reaction, MACR was adsorbed on the surface of CeO2-Mg(OH)2, upon which methanol was simultaneously activated for esterifying the adsorbed MACR. Hemiacetal-form intermediate species were subsequently produced and oxidized to MMA on the surface of the electron-rich Au nanoparticles bound to partially reduced CeO2−x with electron-donating properties. The present study provides new insights into the design of SMSI-induced supported-metal-nanoparticles for the development of novel, multifunctional, and heterogeneous catalysts.

scholarly journals Efficient Synthesis of Methyl Methacrylate by One Step Oxidative Esterification over Zn-Al-Mixed Oxides Supported Gold Nanocatalysts

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 162
Author(s):  
Huayin Li ◽  
Yuan Tan ◽  
Xingkun Chen ◽  
Wenshao Yang ◽  
Chuanqi Huang ◽  
...  
Keyword(s):  
Methyl Methacrylate ◽  
Mixed Oxides ◽  
Gold Catalyst ◽  
Co Adsorption ◽  
Gold Catalysts ◽  
Esterification Reaction ◽  
X Ray ◽  
Oxidative Esterification ◽  
One Step ◽  
Supported Gold

Methyl methacrylate (MMA) is an important monomer in fine chemicals. The synthesis of MMA by one-step oxidative esterification from methacrolein with methanol over a heterogeneous catalyst with high activity, selectivity and stability is highly desirable. Herein, Zn-Al-hydrotalcites (HTs)-supported atomically precise Au25 nanoclusters with different molar ratios of Zn2+/Al3+ were prepared and used as the precursors for this reaction. They exhibited good performances in comparison with the gold catalysts prepared by the deposition precipitation method. The structural and electronic properties were evaluated by various characterization technologies, including X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) of CO adsorption, X-ray photoelectron spectroscopy (XPS), and CO2 temperature-programmed desorption (TPD). The combined characterization results suggested that the adsorption property of gold and the basicity of the catalyst contributes to their high activities. Substrates extended experiments and stability tests implied the potential application of Zn-Al-mixed oxides supported gold catalysts, which paves a new way for supported gold catalyst in the one-step oxidation esterification reaction.

scholarly journals Surface Stoichiometry and Depth Profile of Tix-CuyNz Thin Films Deposited by Magnetron Sputtering

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3191
Author(s):  
Arun Kumar Mukhopadhyay ◽  
Avishek Roy ◽  
Gourab Bhattacharjee ◽  
Sadhan Chandra Das ◽  
Abhijit Majumdar ◽  
...  
Keyword(s):  
Magnetron Sputtering ◽  
Photoelectron Spectroscopy ◽  
Film Surface ◽  
Grazing Incidence ◽  
X Ray Diffraction ◽  
X Ray ◽  
Relative Composition ◽  
Transmission Electron ◽  
Deposited Film ◽  
Deposited Films

We report the surface stoichiometry of Tix-CuyNz thin film as a function of film depth. Films are deposited by high power impulse (HiPIMS) and DC magnetron sputtering (DCMS). The composition of Ti, Cu, and N in the deposited film is investigated by X-ray photoelectron spectroscopy (XPS). At a larger depth, the relative composition of Cu and Ti in the film is increased compared to the surface. The amount of adventitious carbon which is present on the film surface strongly decreases with film depth. Deposited films also contain a significant amount of oxygen whose origin is not fully clear. Grazing incidence X-ray diffraction (GIXD) shows a Cu3N phase on the surface, while transmission electron microscopy (TEM) indicates a polycrystalline structure and the presence of a Ti3CuN phase.

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