Research ArticleChemistry

High-loading single Pt atom sites [Pt-O(OH)x] catalyze the CO PROX reaction with high activity and selectivity at mild conditions

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Science Advances  17 Jun 2020:
Vol. 6, no. 25, eaba3809
DOI: 10.1126/sciadv.aba3809
  • Fig. 1 Characterization of as prepared supported Pt catalysts.

    (A) CO DRIFTS of Pt/Al2O3 and Pt1-Ox-K/Al2O3. (B) EXAFS fitting of as-prepared Pt1-Ox-K/Al2O3. FT, Fourier transform. (C) Representative AC-HAADF-STEM image of Pt1-Ox-K/Al2O3. (D) Plot of WGS activity at 275°C versus Pt loading of different Pt-based catalysts (30 ml/min, 10% CO, 3% H2O, 100 mg of catalyst loading; each data point was obtained by averaging four data points of stability test).

  • Fig. 2 Catalytic tests of Pt-based catalysts.

    (A) Production of CO2 and H2 from CO-TPR over Pt/Al2O3 (black) and Pt1-Ox-K/Al2O3 (green). (B) Activity of CO PROX of supported single–Pt atom and Pt NP catalysts versus Pt loading (reaction conditions: 1% CO, 1% O2, 40% H2, 20 ml/min,100 mg of catalyst, 80°C); each data point is an average of five data points. (C) Conversion of CO at 80° 100°, and 110°C, respectively, over Pt1-Ox-Cs/SiO2, Pt1-Ox-K/Al2O3, Pt/Al2O3, and Pt/SiO2. (D) O2 Selectivity of Pt/Al2O3 and Pt1-Ox-K/Al2O3. All catalysts were calcined at 200°C for 2 hours and then reduced in H2 at 150°C for 0.5 hours. CO-TPR conditions: 10% CO, 30 ml/min, 100 mg of catalyst, 5°C/min; PROX test conditions for (C) and (D): 1% CO, 1% O2, 40% H2, 10 ml/min, 100 mg of catalyst, 5°C/min; the data were obtained by averaging five data points of the stability test.

  • Fig. 3 Stability of [Pt1-Ox-(OH)y] species for CO PROX reaction.

    (A) Cyclic stability test of 1.0 wt % Pt1-Ox-Cs/SiO2 from 373 to 393 K, 1% CO, 1% O2, 40% H2, 50 ml/min, 100 mg of catalyst, 5°C/min. (B) XANES spectra of as-prepared 1.0 wt % Pt1-O-Cs/SiO2 and operando under CO PROX reaction conditions; 1% CO, 1% O2, 40% H2, 20 ml/min, reaction temperature: 120°C. a.u., arbitrary unit. (C) EXAFS fitting of 1.0 wt % Pt1-Ox-Cs/SiO2 under the reaction conditions in (B). (D) AC-HAADF-STEM images of spent 1.0 wt % Pt1-Ox-K/Al2O3; reaction conditions: 1% CO, 1% O2, 40% H2, 20 ml/min, reaction temperature: 120°C, 1 hour.

  • Fig. 4 Mechanistic study of CO PROX over the single–Pt atom catalysts.

    (A) Arrhenius plot of the WGS turnover frequency (TOF) over various single–Pt atom catalysts. (B) Promotion effect of H2O and H2 for CO oxidation over 1.0 wt % Pt1-Ox-Cs/SiO2. (C) Arrhenius plot of CO oxidation with and without H2 over 1.0 wt % Pt1-Ox-Cs/SiO2. (D) Linear plot of WGS reactivity and CO PROX reactivity versus active surface OH groups. WGS test conditions: 10% CO, 3% H2O, 30 ml/min, 100 mg of catalyst loading, 250°C (data were obtained by averaging three stability test results). CO PROX reaction conditions: 1% CO, 1% O2, 40% H2, 50 ml/min,50 mg of catalyst, 5°C/min, 115°C (data were obtained by averaging five stability tests). CO oxidation reaction conditions: 1% CO, 1% O2, 50 ml/min, 50 mg of catalyst, 5°C/min.

Supplementary Materials

  • Supplementary Materials

    High-loading single Pt atom sites Pt-O(OH)x catalyze the CO PROX reaction with high activity and selectivity at mild conditions

    Sufeng Cao, Yanyan Zhao, Sungsik Lee, Shize Yang, Jilei Liu, Georgios Giannakakis, Mengwei Li, Mengyao Ouyang, Dunwei Wang, E. Charles H. Sykes, Maria Flytzani-Stephanopoulos

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