Dynamic Characterization of the Intermediates for Low-Temperature PROX Reaction of CO in H<sub>2</sub>—Oxidation of CO with OH via HCOO Intermediate

Tanaka, Kenichi; Shou, Masashi; He, Hong; Shi, Xun; Zhang, Xiuli

doi:10.1021/jp902322m

Cited by 65 publications

(67 citation statements)

References 33 publications

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“…In the presence of H 2 , the surface of Au/TiO 2 catalyst was covered by H 2 O and OH groups in the oxidation of CO . A FTIR study of CO oxidation on FeO x /Pt inverse catalyst indicated that the surface OH species can directly react with the COOH to produce CO 2 . The DFT calculation suggested that the reaction of OH species with CO went through a smaller barrier compared to the reaction CO + O → CO 2 on metal based catalyst .…”

Section: Discussionmentioning

confidence: 99%

More active Ir subnanometer clusters than single‐atoms for catalytic oxidation of CO at low temperature

et al. 2017

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This work reported the adsorption and reaction performance of FeOx supported subnanometer cluster and single‐atom Ir catalysts for the oxidation of CO at low temperature. By varying the pretreatment temperature and Ir loading, the single‐atom and subnanometer cluster Ir catalysts were obtained. The Ir subnanometer clusters exhibited higher activity for the oxidation of CO with or without the presence of H2 than the single‐atom counterpart. By using adsorption microcalorimetry and in situ infrared spectroscopy measurements, it was found that the Ir subnanometer clusters not only promoted the adsorption and reaction of CO and O2 but also facilitated the formation of OH species from reaction between H2 and O2, thus opening a new reaction pathway between CO and OH species to produce CO2 compared with that between CO and O species on the single‐atom counterpart. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4003–4012, 2017

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Section: Discussionmentioning

confidence: 99%

More active Ir subnanometer clusters than single‐atoms for catalytic oxidation of CO at low temperature

et al. 2017

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“…The strong band near 2048 cm À1 is assignable to linear CO species on the Pt surface, [12,16] which is slightly shifted to lower frequency than that obtained under a flow of pure CO (2085 cm À1 , Figure S5) probably as a result of lower CO coverage. [17,18] The band at 3278 cm À1 resulted from the formation of H 2 O. Moreover, bands at 2978, 1730, and 1421 cm À1 can be assigned to physical adsorption of formic acid on the MCM-41 surface, [19] while two other bands at 2941 and 1574 cm À1 are attributed to adsorption of formate species on MCM-41 ( Figure S6c).…”

Section: Methodsmentioning

confidence: 98%

Low‐Temperature Oxidation of Ethylene over Platinum Nanoparticles Supported on Mesoporous Silica

2013

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Ethylene is a gaseous volatile organic compound (VOC) that works as a plant hormone to inhibit or promote plant growth. Ethylene released from fruits, vegetables, and flowers can accelerate aging and spoiling of plants even in refrigerators at low temperature. Consequently, the removal of trace amounts of ethylene at low temperature (ca. 0 8C) is imperative.Previously, biotechnological materials, such as soil bacteria, dry biobeds, and biofilters were applied for removal of ethylene. [1][2][3][4] However, high production costs and inefficiency in removing trace amounts of ethylene were drawbacks of these methods. Several photocatalysts have also been used, [5][6][7][8] but this resulted in limited application because of the more complicated working conditions required.Many attempts have been made by Hao et al. to develop gold catalysts supported on Co 3 O 4 for the removal of ethylene at low temperature. First, 2 wt % Au/Co 3 O 4 catalyst prepared by a deposition-precipitation method showed only 7.4 % conversion of ethylene at 20 8C from a relatively low concentration (1050 ppm). [9] A more active catalyst, 2.5 wt % Au nanoparticles supported on mesoporous Co 3 O 4 , was later prepared by a nanocasting method, but the catalytic activity was still insufficient for complete removal of trace (50 ppm) ethylene at 0 8C despite the complicated preparation method. [10] Gold nanoparticles supported on Co 3 O 4 rods recently prepared by a hydrothermal method solved the timeconsuming problem of catalyst preparation; however, the method afforded no significant improvement in catalytic activity. [11] Therefore, further catalyst screening is still necessary to find sufficiently active catalysts to remove low concentrations of ethylene.Herein, we report the catalytic performance of Pt nanoparticles supported on mesoporous silica MCM-41 for ethylene oxidation under low-temperature conditions. This study has revealed the influence of metals (Pt, Pd, Au, and Ag) and supports (MCM-41, SiO 2 , Al 2 O 3 , ZrO 2 , and TiO 2 ) on the catalytic performance. The Pt nanoparticles supported on MCM-41 exhibited the highest activity and demonstrated excellent durability in prolonged reaction time or recycle use.The conversion of 50 ppm ethylene over 1 wt % Pt/MCM-41 at 0 8C was over 99.8 %. To our knowledge, this is the highest conversion of ethylene oxidation at low temperature reported to date.All of the catalysts were prepared by using a typical wet impregnation method. Characterization of the catalysts was conducted by various physicochemical methods. The structural parameters are summarized in Table 1 and Table S1 (in the Supporting Information). The small-angle X-ray diffraction (XRD) patterns of MCM-41 and 5 wt % Pt/MCM-41 (Figure S1a) are consistent with the literature, [12] and peaks appeared at (100), (110), and (200), a characteristic of a typical two-dimensional hexagonal structure of mesopores in MCM-41. This result indicates that the mesoporous structure remains unchanged after the incorporation of Pt nanoparticles. However, n...

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“…7 On the other hand, various studies have shown that H 2 promotes low-temperature CO oxidation, although the promotion mechanism is under debate. [8][9][10] Previously, we reported that Ir-Fe/SiO 2 catalyst is highly active and selective for the PROX reaction. 11 Compared with Ir/SiO 2 , the addition of Fe not only weakens the adsorption of CO or H 2 on the Ir sites, but also greatly increases the adsorption of O 2 on the FeO x sites.…”

Section: Introductionmentioning

confidence: 99%

Microkinetic Study of CO Oxidation and PROX on Ir−Fe Catalyst

Li¹,

Wang²,

Zhang³

et al. 2011

Ind. Eng. Chem. Res.

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A microkinetic analysis of the preferential oxidation of CO in H 2 over Ir-Fe/SiO 2 catalyst is reported. Based on the results of in situ diffuse reflectance infrared spectroscopy, microcalorimetry, Mössbauer spectroscopy, and steady-state kinetic experiments in a microreactor, a microkinetic model is proposed that predicts the experimental results well. The model suggests that the reaction between adsorbed H and O for the formation of OH is rate-limiting for the PROX reaction, whereas the surface reaction between adsorbed CO and O is rate-determining for CO oxidation. In addition, the model predicts that the oxidation of adsorbed CO by surface OH is the dominant pathway for the PROX reaction. The surface coverages of different intermediates are also predicted by the model. According to this model, we can conclude that the presence of H 2 increases the surface concentration of OH and, hence, lowers the activation energy and increases the rate of the PROX reaction.

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Dynamic Characterization of the Intermediates for Low-Temperature PROX Reaction of CO in H₂—Oxidation of CO with OH via HCOO Intermediate

Cited by 65 publications

References 33 publications

More active Ir subnanometer clusters than single‐atoms for catalytic oxidation of CO at low temperature

More active Ir subnanometer clusters than single‐atoms for catalytic oxidation of CO at low temperature

Low‐Temperature Oxidation of Ethylene over Platinum Nanoparticles Supported on Mesoporous Silica

Microkinetic Study of CO Oxidation and PROX on Ir−Fe Catalyst

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Dynamic Characterization of the Intermediates for Low-Temperature PROX Reaction of CO in H2—Oxidation of CO with OH via HCOO Intermediate

Cited by 65 publications

References 33 publications

More active Ir subnanometer clusters than single‐atoms for catalytic oxidation of CO at low temperature

More active Ir subnanometer clusters than single‐atoms for catalytic oxidation of CO at low temperature

Low‐Temperature Oxidation of Ethylene over Platinum Nanoparticles Supported on Mesoporous Silica

Microkinetic Study of CO Oxidation and PROX on Ir−Fe Catalyst

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Dynamic Characterization of the Intermediates for Low-Temperature PROX Reaction of CO in H₂—Oxidation of CO with OH via HCOO Intermediate