CO-assisted tandem system for the direct conversion of methane to methanol

Abstract

The selective oxidation of methane (CH₄) to methanol (CH₃OH) requires efficient C−H activation while limiting product over-oxidation. Here a CO-assisted Pt/CeO₂–aqueous Cu tandem system is developed for selective CH₄ oxidation in aqueous media. CO adsorbs strongly on Pt and serves as both a surface regulator and a co-reactant in O₂ activation. Density functional theory (DFT) calculations predict a downward shift of 0.73 eV in the Pt d-band center on the model Pt(111) surface, indicating a modified adsorption environment. Isotope-labeling and sequential-reaction experiments identify gas-phase O₂ as the primary oxygen source incorporated into CH₃OH and support a CO-coupled O₂ activation process. Mobile aqueous Cu species are proposed to contribute to redox mediation, potentially limiting the accumulation of excess reactive oxygen and suppressing CH₃OH overoxidation. Under optimized conditions, the system achieves a CH₃OH yield rate of 14.38 mmol/(g_cat·h) with 100% CH₃OH selectivity among the detected liquid-phase products. This work demonstrates a tandem strategy for independently regulating oxygen activation and product preservation during selective C−H oxidation.

Graphical abstract

Keywords

methane selective oxidation / heterogeneous tandem catalysis / electronic modulation

References

[1] Olah G A . Beyond oil and gas: The methanol economy. Angewandte Chemie International Edition, 2005, 44(18): 2636–2639

[2] Schwach P , Pan X L , Bao X H . Direct conversion of methane to value-added chemicals over heterogeneous catalysts: Challenges and prospects. Chemical Reviews, 2017, 117(13): 8497–8520

[3] Ruppel C D , Kessler J D . The interaction of climate change and methane hydrates. Reviews of Geophysics, 2017, 55(1): 126–168

[4] Alvarez R A , Zavala-Araiza D , Lyon D R . et al. Assessment of methane emissions from the U. S. oil and gas supply chain. Science, 2018, 361(6398): 186–188

[5] Lunsford J H . Catalytic conversion of methane to more useful chemicals and fuels: A challenge for the 21st century. Catalysis Today, 2000, 63(2-4): 165–174

[6] Guo X G , Fang G Z , Li G . et al. Direct, nonoxidative conversion of methane to ethylene, aromatics, and hydrogen. Science, 2014, 344(6184): 616–619

[7] McFarland E . Unconventional chemistry for unconventional natural gas. Science, 2012, 338(6105): 340–342

[8] Latimer A A , Kulkarni A R , Aljama H . et al. Understanding trends in C–H bond activation in heterogeneous catalysis. Nature Materials, 2017, 16(2): 225–229

[9] Sushkevich V L , Palagin D , Ranocchiari M . et al. Selective anaerobic oxidation of methane enables direct synthesis of methanol. Science, 2017, 356(6337): 523–527

[10] Shilov A E , Shul'pin G B . Activation of C−H bonds by metal complexes. Chemical Reviews, 1997, 97(8): 2879–2932

[11] Williams C , Carter J H , Dummer N F . et al. Selective oxidation of methane to methanol using supported AuPd catalysts prepared by stabilizer-free sol-immobilization. ACS Catalysis, 2018, 8(3): 2567–2576

[12] Ahlquist M , Nielsen R J , Periana R A . et al. Product protection, the key to developing high performance methane selective oxidation catalysts. Journal of the American Chemical Society, 2009, 131(47): 17110–17115

[13] Palkovits R , Antonietti M , Kuhn P . et al. Solid catalysts for the selective low-temperature oxidation of methane to methanol. Angewandte Chemie International Edition, 2009, 48(37): 6909–6912

[14] Yu T , Li Z , Lin L . et al. Highly selective oxidation of methane into methanol over Cu-promoted monomeric Fe/ZSM-5. ACS Catalysis, 2021, 11(11): 6684–6691

[15] Periana R A , Taube D J , Evitt E R . et al. A mercury-catalyzed, high-yield system for the oxidation of methane to methanol. Science, 1993, 259(5093): 340–343

[16] Periana R A , Taube D J , Gamble S . et al. Platinum catalysts for the high-yield oxidation of methane to a methanol derivative. Science, 1998, 280(5363): 560–564

[17] Groothaert M H , Smeets P J , Sels B F . et al. Selective oxidation of methane by the bis(μ-oxo)dicopper core stabilized on ZSM-5 and mordenite zeolites. Journal of the American Chemical Society, 2005, 127(5): 1394–1395

[18] Grundner S , Markovits M A C , Li G N . et al. Single-site trinuclear copper oxygen clusters in mordenite for selective conversion of methane to methanol. Nature Communications, 2015, 6: 7546

[19] Ab Rahim M H , Forde M M , Jenkins R L . et al. Oxidation of methane to methanol with hydrogen peroxide using supported gold-palladium alloy nanoparticles. Angewandte Chemie International Edition, 2013, 52(4): 1280–1284

[20] Agarwal N , Freakley S J , McVicker R U . et al. Aqueous Au–Pd colloids catalyze selective CH₄ oxidation to CH₃OH with O₂ under mild conditions. Science, 2017, 358(6360): 223–227

[21] Sun S M , Barnes A J , Gong X X . et al. Lanthanum modified Fe-ZSM-5 zeolites for selective methane oxidation with H₂O₂. Catalysis Science & Technology, 2021, 11(24): 8052–8064

[22] Li M W , Shan J J , Giannakakis G . et al. Single-step selective oxidation of methane to methanol in the aqueous phase on iridium-based catalysts. Applied Catalysis B: Environmental, 2021, 292: 120124

[23] Shan J J , Li M W , Allard L F . et al. Mild oxidation of methane to methanol or acetic acid on supported isolated rhodium catalysts. Nature, 2017, 551(7682): 605–608

[24] Pantu P , Kim K , Gavalas G R . Methane partial oxidation on Pt/CeO₂–ZrO₂ in the absence of gaseous oxygen. Applied Catalysis A: General, 2000, 193(1-2): 203–214

[25] Carlsson P A , Skoglundh M . Low-temperature oxidation of carbon monoxide and methane over alumina and ceria supported platinum catalysts. Applied Catalysis B: Environmental, 2011, 101(3–4): 669–675

[26] Wei D Y , Yue M F , Qin S N . et al. In situ Raman observation of oxygen activation and reaction at platinum-ceria interfaces during CO oxidation. Journal of the American Chemical Society, 2021, 143(38): 15635–15643

[27] Zhao H B , Gao Y L , Wang Y . et al. Coordination restraint of Rh–Cu diatomic catalyst and C–H bond oxygen insertion for methanol synthesis. Nature Communications, 2026, 17(1): 3299

[28] Ahn S Y , Jang W J , Shim J O . et al. CeO₂-based oxygen storage capacity materials in environmental and energy catalysis for carbon neutrality: Extended application and key catalytic properties. Catalysis Reviews, 2024, 66(4): 1316–1399

[29] Tang Y , Li Y T , Fung V . et al. Single rhodium atoms anchored in micropores for efficient transformation of methane under mild conditions. Nature Communications, 2018, 9(1): 1231

[30] Oda A , Ichino K , Yamamoto Y . et al. Hydrophobic, acid-free zeolite-confined Pt–Cu nanoalloys break activity-selectivity limits in low-temperature methane-to-methanol oxidation. Journal of the American Chemical Society, 2025, 147(33): 30009–30021

[31] Yu J , Qin X T , Yang Y S . et al. Highly stable Pt/CeO₂ catalyst with embedding structure toward water–gas shift reaction. Journal of the American Chemical Society, 2024, 146(1): 1071–1080

[32] Huang Z P , Cao S Y , Yu J H . et al. Total oxidation of light alkane over phosphate-modified Pt/CeO₂ catalysts. Environmental Science & Technology, 2022, 56(13): 9661–9671

[33] Bohigues B , Rojas-Buzo S , Salusso D . et al. Overcoming activity/stability tradeoffs in CO oxidation catalysis by Pt/CeO₂. Nature Communications, 2025, 16(1): 7451

[34] Ma L C , Ding C M , Wang J W . et al. In situ surface chemical properties and catalytic performances of Pt/CeO₂ catalyst in methane partial oxidation under different conditions. Applied Surface Science, 2023, 609: 155195

[35] Pastor-Pérez L , Ramos-Fernández E V , Sepúlveda-Escribano A . Effect of the CeO₂ synthesis method on the behaviour of Pt/CeO₂ catalysis for the water-gas shift reaction. International Journal of Hydrogen Energy, 2019, 44(39): 21837–21846

[36] Bugrova T A , Kharlamova T S , Svetlichnyi V A . et al. Insights into formation of Pt species in Pt/CeO₂ catalysts: Effect of treatment conditions and metal-support interaction. Catalysis Today, 2021, 375: 36–47

[37] Zhang L , Chen W , Lu Y X . et al. Electrooxidation of thymol or carvacrol to obtain thymoquinone on defective Pt/CeO₂ catalyst. Advanced Functional Materials, 2025, 35(33): 2424617

[38] Peng R S , Sun X B , Li S J . et al. Shape effect of Pt/CeO₂ catalysts on the catalytic oxidation of toluene. Chemical Engineering Journal, 2016, 306: 1234–1246

[39] Murphin Kumar P S , Thiripuranthagan S , Imai T . et al. Pt nanoparticles supported on mesoporous CeO₂ nanostructures obtained through green approach for efficient catalytic performance toward ethanol electro-oxidation. ACS Sustainable Chemistry & Engineering, 2017, 5(12): 11290–11299

[40] Yang Q L , Li L , Wang X Y . et al. Tunable metal-support interaction of Pt/CeO₂ catalyst via surfactant-assisted strategy: Insight into the total oxidation of CO and toluene. Journal of Hazardous Materials, 2022, 424: 127601

[41] Pereira-Hernández X I , DeLaRiva A , Muravev V . et al. Tuning Pt-CeO₂ interactions by high-temperature vapor-phase synthesis for improved reducibility of lattice oxygen. Nature Communications, 2019, 10(1): 1358

[42] Chin Y H , Buda C , Neurock M . et al. Reactivity of chemisorbed oxygen atoms and their catalytic consequences during CH₄–O₂ catalysis on supported Pt clusters. Journal of the American Chemical Society, 2011, 133(40): 15958–15978

[43] Allian A D , Takanabe K , Fujdala K L . et al. Chemisorption of CO and mechanism of CO oxidation on supported platinum nanoclusters. Journal of the American Chemical Society, 2011, 133(12): 4498–4517

[44] Tan W , Xie S H , Le D . et al. Fine-tuned local coordination environment of Pt single atoms on ceria controls catalytic reactivity. Nature Communications, 2022, 13(1): 7070

[45] Wang J J , Sauter E , Nefedov A . et al. Dynamic structural evolution of ceria-supported Pt particles: A thorough spectroscopic study. The Journal of Physical Chemistry C, 2022, 126(21): 9051–9058

[46] Moteki T , Tominaga N , Ogura M . Mechanism investigation and product selectivity control on CO-assisted direct conversion of methane into C1 and C2 oxygenates catalyzed by zeolite-supported Rh. Applied Catalysis B: Environmental, 2022, 300: 120742

[47] Kitchin J R , Nørskov J K , Barteau M A . et al. Modification of the surface electronic and chemical properties of Pt(111) by subsurface 3d transition metals. The Journal of Chemical Physics, 2004, 120(21): 10240–10246

[48] Skoplyak O , Menning C A , Barteau M A . et al. Experimental and theoretical study of reactivity trends for methanol on Co/Pt(111) and Ni/Pt(111) bimetallic surfaces. The Journal of Chemical Physics, 2007, 127(11): 114707

[49] Tang H L , Ma Y Q , Zheng G H . et al. In-situ generation of highly-reactive Fe^IV=O and its contribution during CH₄ conversion to CH₃OH. Applied Catalysis B: Environment and Energy, 2025, 362: 124780

[50] Dong G X , Zhang M R , Su K . et al. Visible-light-driven and selective methane conversion to oxygenates with air on a halide-perovskite-based photocatalyst under mild conditions. Journal of Materials Chemistry A, 2023, 11(18): 9989–9999

[51] Jia T K , Wang W J , Xu M Y . et al. Water vapor-assisted photocatalytic methane conversion over calcined Zn–Fe layered double hydroxides. ACS Catalysis, 2025, 15(19): 16550–16559

[52] Trinchero A , Hellman A , Grönbeck H . Methane oxidation over Pd and Pt studied by DFT and kinetic modeling. Surface Science, 2013, 616: 206–213

[53] Qi W J , Ran J Y , Wang R R . et al. Kinetic mechanism of effects of hydrogen addition on methane catalytic combustion over Pt(1 1 1) surface: A DFT study with cluster modeling. Computational Materials Science, 2016, 111: 430–442

[54] Liu Y J , Wang F , Wang X S . et al. Synergistic Fe sites and Brønsted acid in Fe/ZSM-5 for methane to acetic acid using a continuous trickle-bed reactor at low-temperature. Applied Catalysis A: General, 2026, 709: 120665

[55] Wang L Q , Jin J T , Li C S . et al. Binary rhodium atom catalyst for selective catalytic conversion of methane to methanol. ACS Nano, 2025, 19(36): 32981–32991

[56] He Y L , Guo F C , Yang K R . et al. In situ identification of reaction intermediates and mechanistic understandings of methane oxidation over hematite: A combined experimental and theoretical study. Journal of the American Chemical Society, 2020, 142(40): 17119–17130

[57] Chi G L , Shen B X , Yu R R . et al. Simultaneous removal of NO and Hg⁰ over Ce–Cu modified V₂O₅/TiO₂ based commercial SCR catalysts. Journal of Hazardous Materials, 2017, 330: 83–92

[58] Zhang L , Ding C Y , Mao M . et al. Valence-tailored inverse ZnO/Cu catalysts with facet-engineered Cu₂O for enhanced CO₂-to-methanol conversion. Applied Catalysis B: Environment and Energy, 2025, 379: 125724

[59] Ling S C , Tu M J , Tang K . et al. Ce lattice-engineered In₂O₃ with Au directs C−C coupling in photocatalytic methane oxidation. ACS Catalysis, 2026, 16(10): 9260–9269

[60] Xu X Y , Lu J L , Su B . et al. Steering charge dynamics and surface reactivity for photocatalytic selective methane oxidation to ethane over Au/Ti-CeO₂. Acta Physico-Chimica Sinica, 2025, 41(11): 100153

[61] Huang Q Y , Cai J J , Wei F . et al. Selective oxidative coupling of methane to ethane with oxygen using an Au/Zn₂Ti₃O₈ photocatalyst under mild conditions. Journal of Materials Chemistry A, 2024, 12(32): 21334–21340

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