Methane Oxidation to Methanol Catalyzed by Cu-Oxo Clusters Stabilized in NU-1000 Metal–Organic Framework

Abstract

Copper oxide clusters synthesized via atomic layer deposition on the nodes of the metal-organic framework (MOF) NU-1000 are active for oxidation of methane to methanol under mild reaction conditions. Analysis of chemical reactivity, in situ X-ray absorption spectroscopy, and density functional theory calculations are used to determine structure/activity relations in the Cu-NU-1000 catalytic system. The Cu-loaded MOF contained Cu-oxo clusters of a few Cu atoms. The Cu was present under ambient conditions as a mixture of ∼15% Cu and ∼85% Cu. The oxidation of methane on Cu-NU-1000 was accompanied by the reduction of 9% of the Cu in the catalyst from Cu to Cu. The products, methanol, dimethyl ether, and CO, were desorbed with the passage of 10% water/He at 135 °C, giving a carbon selectivity for methane to methanol of 45-60%. Cu oxo clusters stabilized in NU-1000 provide an active, first generation MOF-based, selective methane oxidation catalyst.

Identifying promising metal–organic frameworks for heterogeneous catalysis via high‐throughput periodic density functional theory

“…As a proof‐of‐concept, we use this HT workflow to screen MOFs with coordinatively unsaturated metal sites, also known as open metal sites (OMSs), for oxidative C—H bond activation. Due to the large economic demand for a catalyst that can directly convert methane to methanol and motivated by prior work involving MOFs for methane conversion, we specifically consider the partial oxidation of methane as the reaction of interest. In the process, we demonstrate the feasibility of a HT‐DFT screening workflow for MOF catalysis and make several recommendations for future work involving HT‐DFT screening studies of MOFs.…”

The special route toward conversion of methane to methanol on a fluffy metal‐free carbon nitride photocatalyst in the presence of H 2 O 2

“…Provided with the above information, photocatalytic methane oxidation on g-CN with the presence of H 2 O 2 has shown its distinctiveness. The mechanism generally proposed for CH 4 oxidation on photocatalysts contained the reactions shown in Equations (7) to (12) with the production of hydrogen and methanol as well as its overoxidized molecules. (The over oxidation processes were listed in Equations (S1)-(S4…”

“…2 To eliminate the extensive energy cost, direct conversion of CH 4 to CH 3 OH has been attempted by mercury catalyzed reactions with acids, 3 and low-temperature catalysis using (Fe, Cu, Co, Ni, etc.) ion exchanged-based zeolites, [4][5][6][7] AuPb colloid, 8 supported AuPd 2,9 and PdPt, 10 Cu-based organic complex, 11,12 etc. as catalysts and H 2 O 2 or/and O 2 as oxidizing agents.…”

Selective C−O Coupling Hidden in the Thermal Reaction of [Al2CuO5]+ with Methane

“…Further, while the effects of doping on the reactions of various heteronuclear metal oxide clusters with methane have been previously discussed, studies on [Cu x M y O z ] + /CH 4 systems are lacking. This question is important in regard to a rational design of Cu‐containing catalysts for the large‐scale conversion of methane, for example, the selective oxidation of methane to methanol by a Cu‐doped metal–organic framework (MOF) …”

“…This question is important in regardt oarational design of Cu-containing catalysts for the large-scale conversion of methane, for example, the selective oxidation of methane to methanol by aC u-doped metal-organic framework (MOF). [24] When mass-selected, thermalized [Al 2 CuO 5 ] + is reacted with CH 4 ,o nly atomic[ Cu] + is generated with ar ate constant of 2.0 AE 0.6 10 À11 cm 3 molecule À1 s À1 ;t his corresponds to an efficiency of 2 AE 0.6 %, relative to the collision rate [25] [Eq. (1) and Figure 1a].…”