Single-step selective oxidation of methane to methanol in the aqueous phase on iridium-based catalysts

Mengwei Li; Junjun Shan; Georgios Giannakakis; Mengyao Ouyang; Sufeng Cao; Sungsik Lee; Lawrence F. Allard; Maria Flytzani-Stephanopoulos

doi:10.1016/j.apcatb.2021.120124

Single-step selective oxidation of methane to methanol in the aqueous phase on iridium-based catalysts

Mengwei Li, Junjun Shan, Georgios Giannakakis, Mengyao Ouyang, Sufeng Cao, Sungsik Lee, Lawrence F. Allard, Maria Flytzani-Stephanopoulos

Nuclear Energy Materials Microanalysis

Research output: Contribution to journal › Article › peer-review

37 Scopus citations

Abstract

In this work, one-step conversion of methane to methanol using molecular oxygen as the oxidant in the presence of CO in aqueous solutions on copper or palladium promoted Ir-ZSM-5 catalyst is first reported. The addition of a second metal to Ir-ZSM-5 promotes the catalyst activity, while product selectivity can be tuned either to methanol on IrCu-ZSM-5 or to formic acid exclusively on IrPd-ZSM-5. Most effective is the combination of the three metal species together. Approximately 1200 μmol/g_cat methanol, or ∼23.4 mol of methanol per mol of Ir, are formed on the IrCuPd trimetallic system (methanol selectivity ∼80 %) at 150 °C in 1 h. Our results also demonstrate that atomically dispersed Ir(I)(CO)₂ species formed in the presence of CO can activate the C–H bond of methane to methyl species at temperatures below 150 °C. The good stability in cyclic operation is an additional attribute, rendering this type of catalyst a “front-runner” in future catalyst development for direct methane-to-liquid oxygenates.

Original language	English
Article number	120124
Journal	Applied Catalysis B: Environmental
Volume	292
DOIs	https://doi.org/10.1016/j.apcatb.2021.120124
State	Published - Sep 5 2021

Funding

The financial support of this work by the U. S. Department of Energy , DOE/ARPA-e grant# DE-AR0000433 , under subcontract from MIT, is gratefully acknowledged. Use of the Advanced Photon Source at Argonne National Laboratory for XAS experiments was supported by the U. S. DOE , Office of Science , Office of Basic Energy Sciences , under Contract No. DE-AC02-06CH11357. Microscopy experiments at Oak Ridge National Laboratory were supported by the U. S. DOE, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office, Propulsion Materials Program. The authors also thank Dr. Adam S. Hoffman and Dr. Simon R. Bare at SLAC National Accelerator Laboratory for assisting with the XAS study and analysis.

Funders	Funder number
U. S. DOE
U.S. Department of Energy	DE-AR0000433
Office of Science
Office of Energy Efficiency and Renewable Energy
Basic Energy Sciences	DE-AC02-06CH11357
Massachusetts Institute of Technology

Keywords

C–H bond activation
Methane
Methanol
Single-atom catalysis

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10.1016/j.apcatb.2021.120124

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title = "Single-step selective oxidation of methane to methanol in the aqueous phase on iridium-based catalysts",

abstract = "In this work, one-step conversion of methane to methanol using molecular oxygen as the oxidant in the presence of CO in aqueous solutions on copper or palladium promoted Ir-ZSM-5 catalyst is first reported. The addition of a second metal to Ir-ZSM-5 promotes the catalyst activity, while product selectivity can be tuned either to methanol on IrCu-ZSM-5 or to formic acid exclusively on IrPd-ZSM-5. Most effective is the combination of the three metal species together. Approximately 1200 μmol/gcat methanol, or ∼23.4 mol of methanol per mol of Ir, are formed on the IrCuPd trimetallic system (methanol selectivity ∼80 %) at 150 °C in 1 h. Our results also demonstrate that atomically dispersed Ir(I)(CO)2 species formed in the presence of CO can activate the C–H bond of methane to methyl species at temperatures below 150 °C. The good stability in cyclic operation is an additional attribute, rendering this type of catalyst a “front-runner” in future catalyst development for direct methane-to-liquid oxygenates.",

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author = "Mengwei Li and Junjun Shan and Georgios Giannakakis and Mengyao Ouyang and Sufeng Cao and Sungsik Lee and Allard, {Lawrence F.} and Maria Flytzani-Stephanopoulos",

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AU - Shan, Junjun

AU - Giannakakis, Georgios

AU - Ouyang, Mengyao

AU - Cao, Sufeng

AU - Lee, Sungsik

AU - Allard, Lawrence F.

AU - Flytzani-Stephanopoulos, Maria

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N2 - In this work, one-step conversion of methane to methanol using molecular oxygen as the oxidant in the presence of CO in aqueous solutions on copper or palladium promoted Ir-ZSM-5 catalyst is first reported. The addition of a second metal to Ir-ZSM-5 promotes the catalyst activity, while product selectivity can be tuned either to methanol on IrCu-ZSM-5 or to formic acid exclusively on IrPd-ZSM-5. Most effective is the combination of the three metal species together. Approximately 1200 μmol/gcat methanol, or ∼23.4 mol of methanol per mol of Ir, are formed on the IrCuPd trimetallic system (methanol selectivity ∼80 %) at 150 °C in 1 h. Our results also demonstrate that atomically dispersed Ir(I)(CO)2 species formed in the presence of CO can activate the C–H bond of methane to methyl species at temperatures below 150 °C. The good stability in cyclic operation is an additional attribute, rendering this type of catalyst a “front-runner” in future catalyst development for direct methane-to-liquid oxygenates.

AB - In this work, one-step conversion of methane to methanol using molecular oxygen as the oxidant in the presence of CO in aqueous solutions on copper or palladium promoted Ir-ZSM-5 catalyst is first reported. The addition of a second metal to Ir-ZSM-5 promotes the catalyst activity, while product selectivity can be tuned either to methanol on IrCu-ZSM-5 or to formic acid exclusively on IrPd-ZSM-5. Most effective is the combination of the three metal species together. Approximately 1200 μmol/gcat methanol, or ∼23.4 mol of methanol per mol of Ir, are formed on the IrCuPd trimetallic system (methanol selectivity ∼80 %) at 150 °C in 1 h. Our results also demonstrate that atomically dispersed Ir(I)(CO)2 species formed in the presence of CO can activate the C–H bond of methane to methyl species at temperatures below 150 °C. The good stability in cyclic operation is an additional attribute, rendering this type of catalyst a “front-runner” in future catalyst development for direct methane-to-liquid oxygenates.

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Single-step selective oxidation of methane to methanol in the aqueous phase on iridium-based catalysts

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Keywords

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