Surface-Confined Atomic Silver Centers Catalyzing Formaldehyde Oxidation

Hu, Pengcheng; Amghouz, Zakariae; Huang, Zhiwei; Xu, Fei; Chen, Yaxin; Tang, Xingfu

doi:10.1021/es504570n

Cited by 130 publications

(87 citation statements)

References 44 publications

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“…[14,15] In particular, hollandite-type manganese oxides (HMO)h aveh igh catalytic activityi nH CHO oxidation because the tunnels izes are suitable for the adsorption and activation of HCHO [16] and for the activation of oxygen. [17] To further enhancet he catalytic performance, noble metals such as Pt, [18] Au, [19] and Ag [20][21][22] were highly dispersed or even atomically dispersed/deposited onto HMO surfaces. However, noble-metal catalysts can only be appliedi ns ome special environments, such as aircraft,f or cost reasons.…”

Section: Introductionmentioning

confidence: 99%

Activating Inert Alkali‐Metal Ions by Electron Transfer from Manganese Oxide for Formaldehyde Abatement

Gao

Chen

Wan

et al. 2017

Chemistry A European J

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Alkali-metal ions often act as promoters rather than active components due to their stable outermost electronic configurations and their inert properties in heterogeneous catalysis. Herein, inert alkali-metal ions, such as K and Rb , are activated by electron transfer from a Hollandite-type manganese oxide (HMO) support for HCHO oxidation. Results from synchrotron X-ray diffraction, absorption, and photoelectron spectroscopies demonstrate that the electronic density of states of single alkali-metal adatoms is much higher than that of K or Rb , because electrons transfer from manganese to the alkali-metal adatoms through bridging lattice oxygen atoms. Electron transfer originates from the interactions of alkali metal d-sp frontier orbitals with lattice oxygen sp orbitals occupied by lone-pair electrons. Reaction kinetics data of HCHO oxidation reveal that the high electronic density of states of single alkali-metal adatoms is favorable for the activation of molecular oxygen. Mn L -edge and O K-edge soft-X-ray absorption spectra demonstrate that lattice oxygen partially gains electrons from the Mn e orbitals, which leads to the upshift in energy of lattice oxygen orbitals. Therefore, the facile activation of molecular oxygen by the electron-abundant alkali-metal adatoms and active lattice oxygen are responsible for the high catalytic activity in complete oxidation of HCHO. This work could assist the design of efficient and cheap catalysts by tuning the electronic states of active components.

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Section: Introductionmentioning

confidence: 99%

Activating Inert Alkali‐Metal Ions by Electron Transfer from Manganese Oxide for Formaldehyde Abatement

Gao

Chen

Wan

et al. 2017

Chemistry A European J

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“…After sulfur adsorption was performed with model diesel, the displacement to higher BE values indicates more positive electronic density of Ag species [27]. The increase in BEs of oxygenated Ag species (368.4 and 374.5 eV) can be assigned to oxygen loss after oxidation reactions, while the broad peaks which emerged at 369.4 and 375.6 eV are ascribed to the formation of an Ag-S-R bridging configuration via π-complexation (S-R = DBT) performed by Ag(0) and also by active Ag-O species [26,43].…”

Section: Characterization Of the Adsorbentsmentioning

confidence: 99%

“…Researchers have observed that adsorbents functionalized with transition metals are capable of capturing aromatic sulfur compounds refractory to HDS processes via π-complexation [25,26]. Furthermore, Ag species dispersed onto metal and semi-metal oxide adsorbents generate materials described as high activity catalysts for oxidation of several toxic compounds such as formaldehyde [27], benzene [28], toluene [29] and carbon monoxide [24], among others.The Ag(0) sites present high reactivity both by adsorbing and activating atmospheric O 2 at ambient conditions (300 K, 1 atm) [30] and by increasing the mobility of lattice oxygens from the adsorbent structure. This increase in mobility can occur by bridging bonds between Ag(0) and the metal oxide molecules [28], but it is also reported by covalent bonding in the case of a more oxidized state of silver as Ag(I), and in a cation exchange of hydrolyzed silica silanol groups (Si-O-H) [31].…”

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Assessment of Ag Nanoparticles Interaction over Low-Cost Mesoporous Silica in Deep Desulfurization of Diesel

et al. 2019

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Chemical interactions between metal particles (Ag or Ni) dispersed in a low-cost MCM-41 M produced from beach sand amorphous silica and sulfur compounds were evaluated in the deep adsorptive desulfurization process of real diesel fuel. N 2 adsorption-desorption isotherms, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy coupled to energy-dispersive X-ray spectroscopy (STEM-EDX) were used for characterizing the adsorbents. HRTEM and XPS confirmed the high dispersion of Ag nanoparticles on the MCM-41 surface, and its chemical interaction with support and sulfur compounds by diverse mechanisms such as π-complexation and oxidation. Thermodynamic tests indicated that the adsorption of sulfur compounds over Ag(I)/MCM-41 M is an endothermic process under the studied conditions. The magnitude of ∆H • (42.1 kJ/mol) indicates that chemisorptive mechanisms govern the sulfur removal. The best fit of kinetic and equilibrium data to pseudo-second order (R 2 > 0.99) and Langmuir models (R 2 > 0.98), respectively, along with the results for intraparticle diffusion and Boyd's film-diffusion kinetic models, suggest that the chemisorptive interaction between organosulfur compounds and Ag nanosites controls sulfur adsorption, as seen in the XPS results. Its adsorption capacity (q m = 31.25 mgS/g) was 10 times higher than that obtained for pure MCM-41 M and double the q m for the Ag(I)/MCM-41 C adsorbent from commercial silica. Saturated adsorbents presented a satisfactory regeneration rate after a total of five sulfur adsorption cycles. catalysts. However, some recalcitrant organosulfur such as thiophene derivatives are not removed by this method [4].Methods based on membrane separation [5], catalytic oxidation [3], biological desulfurization [6], and adsorption [1,[7][8][9][10][11] have been developed for desulfurizing fuels. Among these techniques, adsorptive desulfurization stands out due to its simplicity, efficiency and low-cost according to the solid chosen as the adsorbent. Activated carbon [1], MOFs [9], , , and MCM-41 [7,11] are currently being investigated for sulfur adsorption from liquid fuels, among other materials.These molecular sieves, especially MCM-41, are extensively applied as supports for adsorbents and heterogeneous catalysts due to their high surface area, ordered structure, and uniform pore size [12]. In general, heterogeneous micrometric size catalysts present low catalytic activity due to slow diffusion of reagents [13]. Therefore, active metal nanoparticles (NPs), which have high catalytic activity due to their high surface-volume ratio and chemical reactivity, have been incorporated into solid supports for increasing their efficiency, recyclability and stability, thus providing more sustainable processes [14][15][16]. When unsupported, the high surface energy of nanocatalysts increases system instability and leads to aggregation, thus resulting in the loss of its catalytic properties. The...

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“…Formaldehyde (HCHO) was classified as Group 1 human carcinogen by the International Agency for Research on Cancer in 2004 [1]. With the increasing use in of biofuels [2], HCHO is a typical pollutant in both indoor and outdoor air, which is a hazard to human health and induces photochemical pollution [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

The variation of cationic microstructure in Mn-doped spinel ferrite during calcination and its effect on formaldehyde catalytic oxidation

Liang

Liu

et al. 2016

Journal of Hazardous Materials

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Surface-Confined Atomic Silver Centers Catalyzing Formaldehyde Oxidation

Cited by 130 publications

References 44 publications

Activating Inert Alkali‐Metal Ions by Electron Transfer from Manganese Oxide for Formaldehyde Abatement

Activating Inert Alkali‐Metal Ions by Electron Transfer from Manganese Oxide for Formaldehyde Abatement

Assessment of Ag Nanoparticles Interaction over Low-Cost Mesoporous Silica in Deep Desulfurization of Diesel

The variation of cationic microstructure in Mn-doped spinel ferrite during calcination and its effect on formaldehyde catalytic oxidation

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