Methanol Reactivity on Silica-Supported Ceria Nanoparticles

Uhlrich, John J.; Yang, Bing; Shaikhutdinov, Shamil K.

doi:10.1007/s11244-014-0296-2

Cited by 9 publications

(7 citation statements)

References 34 publications

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“…The low methanol coverage of θ = 0.125 used in this work might represent another reason for the discrepancy between theory and observation. Further TPD experiments using ceria nanoparticles on a silica support yielded two distinct formaldehyde desorption peaks at 435 and 590 K. 88 The second peak was attributed to (111) facets, and the peak at 435 K could either originate from edges or (100) facets. Our calculations support the interpretation that the peak at 435 K is caused by (100) facets.…”

Section: Resultsmentioning

confidence: 99%

Activity versus Selectivity of the Methanol Oxidation at Ceria Surfaces: A Comparative First-Principles Study

Kropp

Paier

2015

J. Phys. Chem. C

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Ceria nanoparticles may expose (100) and (111) facets depending on the preparation method. Motivated by that, we study the reactions of methanol with the CeO 2 (100) surface using dispersion-corrected PBE+U subject to periodic boundary conditions and compare with results for the CeO 2 (111) surface. At (100) facets, the oxidative dehydrogenation of methanol to formaldehyde occurs with an intrinsic barrier of only 0.94 eV (91 kJ/mol), which is significantly lower than the corresponding barrier of 1.23 eV (119 kJ/mol) at the (111) surface. The lower barrier maps to lower formaldehyde desorption temperatures as observed in temperature-programmed desorption spectroscopy. The higher activity is in accordance with predicted lower oxygen defect formation energy in the (100) surface. Thus, defect formation energies are valid reactivity descriptors for oxidation reactions following a Mars-van Krevelen mechanism. At both surfaces, formaldehyde either desorbs or forms a bridging dioxymethylene intermediate, which can be further oxidized into carbon oxides. However, formaldehyde desorption from the (100) surface is significantly more endothermic. Thus, methanol oxidation at the (100) surface is predicted to yield both formaldehyde and carbon oxides, whereas at the (111) surface, formaldehyde can easily desorb. Therefore, the desorption step appears to be the key to the selectivity of methanol oxidation to formaldehyde.

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Section: Resultsmentioning

confidence: 99%

Activity versus Selectivity of the Methanol Oxidation at Ceria Surfaces: A Comparative First-Principles Study

Kropp

Paier

2015

J. Phys. Chem. C

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“…[37,39] The sharp band at 1100 cm ¡1 is attributed to the CÀO stretching for methoxyl groups. [40] The peak of 625 cm ¡1 is due to cis-CH-swing and the CH, CH 2 rock. [29] Above all, it can be inferred that the lignin is bounded to the surface of Cu 2 O nanoparticles as indicated in Figure 4.…”

Section: ¡1mentioning

confidence: 99%

Green and gentle synthesis of Cu₂O nanoparticles using lignin as reducing and capping reagent with antibacterial properties

2015

Journal of Experimental Nanoscience

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In this work, Cu 2 O nanoparticles of a particular shape were prepared by an ecofriendly, gentle and low-cost synthetic method using lignin as a reducing and capping reagent. Structure and morphology of the Cu 2 O nanoparticles were characterised by high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction (XRD) and Fourier-transform (FT-IR) spectroscopy. The results established that Cu 2 O nanoparticles coated by lignin showed a particular shape. The morphology of Cu 2 O nanoparticles presented as some loose accumulation of particles just like broccoli, and the particle size range was between 100 and 200 nm. And, the XRD revealed the structure of crystalline of the Cu 2 O nanoparticles. In addition, the sterilisation of Cu 2 O nanoparticles on Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) was also investigated. The Cu 2 O nanoparticles showed effective bactericidal activity against E. coli and S. aureus. The antibacterial rate could get 100% after 30 min with 4.0 g/L Cu 2 O nanoparticles. Furthermore, the Cu 2 O nanoparticles were confirmed to have low cytotoxicity.

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“…Hence, the oxidation of methanol to formaldehyde has been extensively studied on metal oxides, especially on titanium and vanadium oxides [23][24][25][26][27][28]. In the case of ceria, most of the investigations have been focused on the (111) facet [29][30][31][32][33]. On this stoichiometric surface, methanol converts into formaldehyde, at ca.…”

Section: Introductionmentioning

confidence: 99%

Unraveling the structure sensitivity in methanol conversion on CeO2: A DFT+U study

Capdevila‐Cortada

García‐Melchor

López

2015

Journal of Catalysis

108

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Highlights:-Structure sensitivity correlates with the surface oxygen content in the methanol decomposition on ceria.-Methanol selectively converts to formaldehyde on ceria (111) and (110) facets.-The CeO 2 (100) facet traps formaldehyde and ultimately enables its oxidation to produce CO+H 2 .-Hydrogen evolution is permitted on (100) due to its ability to stabilize a hydrogen precursor.-Formaldehyde can easily exchange its oxygen with the lattice in all facets. 2 ABSTRACTMethanol decomposes on oxides, in particular CeO 2 , producing either formaldehyde or CO as main products. This reaction presents structure sensitivity to the point that the major product obtained depends on the facet exposed in the ceria nanostructures. Our Density Functional Theory (DFT) calculations illustrate how the control of the surface facet and its inherent stoichiometry determine the sole formation of formaldehyde on the closed surfaces or the more degraded byproducts on the open facets (CO and hydrogen). In addition, we found that the regular (100) termination is the only one that allows hydrogen evolution via a hydride-hydroxyl precursor. The fundamental insights presented for the differential catalytic reactivity of the different facets agree with the structure sensitivity found for ceria catalysts in several reactions and provide a better understanding on the need of shape control in selective processes.3

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Methanol Reactivity on Silica-Supported Ceria Nanoparticles

Cited by 9 publications

References 34 publications

Activity versus Selectivity of the Methanol Oxidation at Ceria Surfaces: A Comparative First-Principles Study

Activity versus Selectivity of the Methanol Oxidation at Ceria Surfaces: A Comparative First-Principles Study

Green and gentle synthesis of Cu₂O nanoparticles using lignin as reducing and capping reagent with antibacterial properties

Unraveling the structure sensitivity in methanol conversion on CeO2: A DFT+U study

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Methanol Reactivity on Silica-Supported Ceria Nanoparticles

Cited by 9 publications

References 34 publications

Activity versus Selectivity of the Methanol Oxidation at Ceria Surfaces: A Comparative First-Principles Study

Activity versus Selectivity of the Methanol Oxidation at Ceria Surfaces: A Comparative First-Principles Study

Green and gentle synthesis of Cu2O nanoparticles using lignin as reducing and capping reagent with antibacterial properties

Unraveling the structure sensitivity in methanol conversion on CeO2: A DFT+U study

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Green and gentle synthesis of Cu₂O nanoparticles using lignin as reducing and capping reagent with antibacterial properties