Maximized Ir atom utilization via downsizing active sites to single-atom scale for highly stable dry reforming of methane

Abstract

Noble metals such as iridium with high Tammann temperature are inclined to sintering resistance and may be promising in the high-temperature dry reforming of methane (DRM) process, yet the low atom utilization remains intractable. Herein, we synthesized Ir/TiO₂ catalysts via the conventional incipient wetness impregnation method and further downsized the Ir species from a nanoparticulate to a single-atom scale by gradually decreasing Ir loadings from 1.0 wt.% to 0.01 wt.%. With the advantage of single atoms for maximized atom utilization, Ir single atoms were employed to enhance atom utilization in the DRM process. Various characterizations, such as aberration-corrected high-angle annular dark-field scanning transmission electron microscopy, CO adsorbed in situ diffuse reflectance infrared Fourier transform spectra and X-ray absorption spectra demonstrated the existence of Ir single atoms in 0.01% and 0.05% Ir/TiO₂. During the DRM process, Ir single-atom catalysts exhibited a better specific reaction rate of as high as 697.71 mol_CH4·g_Ir^-1·h^-1 at 750 °C compared with that over Ir nanoparticles of mere 447.12 mol_CH4·g_Ir^-1·h^-1, which unambiguously showed the remarkable Ir atom utilization over Ir single atoms. Besides, the Ir single-atom catalysts also exhibited excellent stability during the DRM process for 50 h and revealed outstanding anti-coking and good sintering-resistance properties examined by the thermal gravimetric analysis-mass spectrometer and Raman spectroscopy. The strategy of employing Ir single atoms for the maximum atom utilization in the high-temperature reaction process can pave the way for better exploitation of noble metals in other industrial reaction processes.

Keywords

Single-atom catalysts / dry reforming of methane / atom utilization / specific reaction rate / iridium

References

[1] Han B,Jiang X.Switchable tuning CO₂ hydrogenation selectivity by encapsulation of the Rh nanoparticles while exposing single atoms.Small2022;18:e2204490

[2] He D,Cao X.Dynamic trap of Ni at elevated temperature for yielding high-efficiency methane dry reforming catalyst.Appl Catal B Environ Energy2024;346:123728

[3] Zhou W,Tang L.Photocatalytic dry reforming of methane enhanced by “dual-path” strategy with excellent low-temperature catalytic performance.Adv Funct Mater2023;33:2214068

[4] Xu Y,Wu M.Review on using molybdenum carbides for the thermal catalysis of CO₂ hydrogenation to produce high-value-added chemicals and fuels.Acta Phys Chim Sin2024;40:2304003

[5] Kawi S,Ni J,Li Z.Progress in synthesis of highly active and stable nickel-based catalysts for carbon dioxide reforming of methane.ChemSusChem2015;8:3556-75

[6] Kathiraser Y,Saw ET,Kawi S.Kinetic and mechanistic aspects for CO₂ reforming of methane over Ni based catalysts.Chem Eng J2015;278:62-78

[7] Yentekakis IV,Artemakis G.A review of recent efforts to promote dry reforming of methane (DRM) to syngas production via bimetallic catalyst formulations.Appl Catal B Environ2021;296:120210

[8] Wittich K,Bottke N.Catalytic dry reforming of methane: insights from model systems.ChemCatChem2020;12:2130-47

[9] Wang Z,Huan Y.Defect and interface engineering for promoting electrocatalytic N-integrated CO₂ co-reduction.Chin J Catal2024;57:1-17

[10] Li T,Lang R.Styrene hydroformylation with in situ hydrogen: regioselectivity control by coupling with the low-temperature water-gas shift reaction.Angew Chem Int Ed Engl2020;59:7430-4

[11] Chen F,Pan X.Pd₁/CeO₂ single-atom catalyst for alkoxycarbonylation of aryl iodides.Sci China Mater2020;63:959-64. (in Chinese)

[12] Zhang Y,Yang X.Tuning reactivity of Fischer-Tropsch synthesis by regulating TiO_x overlayer over Ru/TiO₂ nanocatalysts.Nat Commun2020;11:3185 PMCID:PMC7314765

[13] Rahmati M,Fletcher TH,Bartholomew CH.Chemical and thermal sintering of supported metals with emphasis on cobalt catalysts during fischer-tropsch synthesis.Chem Rev2020;120:4455-533

[14] Chu W,Chernavskii PA.Glow-discharge plasma-assisted design of cobalt catalysts for Fischer-Tropsch synthesis.Angew Chem Int Ed Engl2008;47:5052-5

[15] Zhang Q,Yang Y.Atomically dispersed metals as potential coke-resistant catalysts for dry reforming of methane.Cell Rep Phys Sci2023;4:101310

[16] Cheng Q,Ou L.Highly efficient and stable methane dry reforming enabled by a single-site cationic Ni catalyst.J Am Chem Soc2023;145:25109-19

[17] Zhang X,Liu Y.A novel Ni-MoC_xO_y interfacial catalyst for syngas production via the chemical looping dry reforming of methane.Chem2023;9:102-16

[18] Feng K,Li Z.Spontaneous regeneration of active sites against catalyst deactivation.Appl Catal B Environ2024;344:123647

[19] Tang Y,Wang Z.Synergy of single-atom Ni₁ and Ru₁ sites on CeO₂ for dry reforming of CH₄.J Am Chem Soc2019;141:7283-93

[20] Carrara C,Lombardo EA.Kinetic and stability studies of Ru/La₂O₃ used in the dry reforming of methane.Top Catal2008;51:98-106

[21] Niu J,E .Liland S, et al. Unraveling enhanced activity, selectivity, and coke resistance of Pt-Ni bimetallic clusters in dry reforming.ACS Catal2021;11:2398-411

[22] Al-Fatesh AS,Abasaeed AE.Effect of Pd on CH₄ reforming with CO₂ catalyzed by Ni over mixed Titian-Alumina support.Adv Mater Res2012;476-8:513-8.

[23] Wang D,Marks TJ,Weitz E.Coking can enhance product yields in the dry reforming of methane.ACS Catal2022;12:8352-62

[24] Jang WJ,Kim HM,Roh HS.A review on dry reforming of methane in aspect of catalytic properties.Catal Today2019;324:15-26

[25] Pakhare D.A review of dry (CO₂) reforming of methane over noble metal catalysts.Chem Soc Rev2014;43:7813-37

[26] Golunski SE.Final analysis: Why use platinum in catalytic converters?.Platin Met Rev2007;51:162

[27] Li H,Tian J,Zhao C.Ultra-durable Ni-Ir/MgAl₂O₄ catalysts for dry reforming of methane enabled by dynamic balance between carbon deposition and elimination.Chem Catal2022;2:1748-63

[28] Huang Y,Zhang Q,Huang W.Enhanced carbon tolerance of hydrotalcite-derived Ni-Ir/Mg(Al)O catalysts in dry reforming of methane under elevated pressures.Fuel Process Technol2022;237:107446

[29] Zhou R,Zhang J.Photo-thermo catalytic dry reforming of methane over Ni-Ir/SiO₂ catalyst.Sci Sin Chim2021;51:1539-48

[30] Nikolaraki E,Panagiotopoulou P.Support induced effects on the Ir nanoparticles activity, selectivity and stability performance under CO₂ reforming of methane.Nanomaterials2021;11:2880 PMCID:PMC8624188

[31] Kim E,Bak J.Stabilizing role of Mo in TiO₂-MoO_x supported Ir catalyst toward oxygen evolution reaction.Appl Catal B Environ2021;280:119433

[32] Maina SCP,Vilella JI.Study of the performance and stability in the dry reforming of methane of doped alumina supported iridium catalysts.Catal Today2020;344:129-42

[33] Jia A,Song T.The effects of TiO₂ crystal-plane-dependent Ir-TiO_x interactions on the selective hydrogenation of crotonaldehyde over Ir/TiO₂ catalysts.Chin J Catal2021;42:1742-54

[34] Hou CC,Sun L.Single-atom iron catalysts on overhang-eave carbon cages for high-performance oxygen reduction reaction.Angew Chem Int Ed Engl2020;59:7384-9

[35] Lang R,Huang Y.Single-atom catalysts based on the metal-oxide interaction.Chem Rev2020;120:11986-2043

[36] Li L,Lin X,Gong J.Theoretical insights into single-atom catalysts.Chem Soc Rev2020;49:8156-78

[37] Wang Y,He Y.Advanced electrocatalysts with single-metal-atom active sites.Chem Rev2020;120:12217-314

[38] Kim JH,Kim J.Reversible ligand exchange in atomically dispersed catalysts for modulating the activity and selectivity of the oxygen reduction reaction.Angew Chem Int Ed Engl2021;60:20528-34

[39] Jeong H,Kim B.Highly durable metal ensemble catalysts with full dispersion for automotive applications beyond single-atom catalysts.Nat Catal2020;3:368-75

[40] Zhu R,Li L.Photo-thermo catalytic oxidation of C₃H₈ and C₃H₆ over the WO₃-TiO₂ supported Pt single-atom catalyst.Acta Physico Chimica Sinica2024;40:2303003

[41] Zhou Y,Qi H.Peripheral-nitrogen effects on the Ru₁ centre for highly efficient propane dehydrogenation.Nat Catal2022;5:1145-56

[42] Han B,Zhang J.A highly active Rh₁/CeO₂ single-atom catalyst for low-temperature CO oxidation.Chem Commun2020;56:4870-3

[43] Akri M,Batiot-dupeyrat C.Highly active and carbon-resistant nickel single-atom catalysts for methane dry reforming.Catalysts2020;10:630

[44] Akri M,Li X.Atomically dispersed nickel as coke-resistant active sites for methane dry reforming.Nat Commun2019;10:5181 PMCID:PMC6858327

[45] Yang J,Jiang Q.Highly active and stable Ir nanoclusters derived from Ir₁/MgAl₂O₄ single-atom catalysts.J Chem Phys2021;154:131105

[46] Bergeret G.3.1.2 Particle size and dispersion measurements. In: Ertl G, Knözinger H, Schüth F, Weitkamp J, editors. Handbook of heterogeneous catalysis. Wiley; 2008. pp. 738-65.

[47] Peng M,Gao R,Liu H.Fully exposed cluster catalyst (FECC): toward rich surface sites and full atom utilization efficiency.ACS Cent Sci2021;7:262-73 PMCID:PMC7908029

[48] Yang XF,Qiao B,Liu J.Single-atom catalysts: a new frontier in heterogeneous catalysis.Acc Chem Res2013;46:1740-8

[49] Lu Y,Yu L.Identification of the active complex for CO oxidation over single-atom Ir-on-MgAl₂O₄ catalysts.Nat Catal2019;2:149-56

[50] Jin R,Li A.Low temperature oxidation of ethane to oxygenates by oxygen over iridium-cluster catalysts.J Am Chem Soc2019;141:18921-5

[51] Zhu Q,Wang L.Enhanced CO₂ utilization in dry reforming of methane achieved through nickel-mediated hydrogen spillover in zeolite crystals.Nat Catal2022;5:1030-7

[52] Zhang Y,Yang X.Tuning selectivity of CO₂ hydrogenation by modulating the strong metal-support interaction over Ir/TiO₂ catalysts.Green Chem2020;22:6855-61

[53] Wang A,Zhang T.Heterogeneous single-atom catalysis.Nat Rev Chem2018;2:65-81

[54] Zuo Z,Wang Z.Dry reforming of methane on single-site Ni/MgO catalysts: importance of site confinement.ACS Catal2018;8:9821-35

[55] Gangarajula Y,Li Q.Operando induced strong metal-support interaction of Rh/CeO₂ catalyst in dry reforming of methane.Appl Catal B Environ2024;343:123503

[56] Zhang Q,Su Y,Qiao B.Catalytic propane dehydrogenation by anatase supported Ni single-atom catalysts.Chin J Catal2024;57:105-13