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Methane Partial Oxidation over [Cu2(μ-O)]2+ and [Cu3(μ-O)3]2+ Active Species in Large-Pore Zeolites
Mahyuddin M.H.a,c, Tanaka T.a, Shiota Y.a, Staykov A.b, Yoshizawa K.a
a Institute for Materials Chemistry and Engineering, IRCCS, Fukuoka, 819-0395, Japan
b International Institute for Carbon-Neutral Energy Research, Kyushu University, Fukuoka, 819-0395, Japan
c Engineering Physics Research Group, Bandung Institute of Technology, Bandung, 40132, Indonesia
[vc_row][vc_column][vc_row_inner][vc_column_inner][vc_separator css=”.vc_custom_1624529070653{padding-top: 30px !important;padding-bottom: 30px !important;}”][/vc_column_inner][/vc_row_inner][vc_row_inner layout=”boxed”][vc_column_inner width=”3/4″ css=”.vc_custom_1624695412187{border-right-width: 1px !important;border-right-color: #dddddd !important;border-right-style: solid !important;border-radius: 1px !important;}”][vc_empty_space][megatron_heading title=”Abstract” size=”size-sm” text_align=”text-left”][vc_column_text]© 2018 American Chemical Society.Copper-containing large-pore zeolites, such as Cu-mordenite (Cu-MOR) and Cu-omega (Cu-MAZ), oxidize methane to yield a high amount of methanol. Two distinct active centers in MOR zeolite, namely, [Cu2(μ-O)]2+ and [Cu3(μ-O)3]2+, have been proposed and debated. In particular, the [Cu2(μ-O)]2+ species was experimentally found to be formed on two different Al pair sites with different reactivities toward methane. However, computational attempts based on density functional theory (DFT) have not been able to confirm them. Moreover, the full cycle of the reaction, which includes methane activation, water-assisted methanol desorption, and a second methane reaction with the active species, has not been well understood yet. In this study, we employed DFT calculations based on the Perdew, Burke, and Ernzerhof functional to reasonably calculate all activation energies involved in such a complete reaction over periodic systems of [Cux(μ-O)y]2+-MOR and -MAZ (x, y = 2, 1 and 3, 3) in the high-spin and low-spin states. We found two Al pair sites in MOR zeolite that form two distinct [Cu2(μ-O)]2+ structures able to cleave the C-H bond of methane with activation energies excellently comparable with the experimental values. Our computational results further suggest that the addition of a water molecule helps the reaction to reduce the high methanol desorption energies. We also show that two of the three bridging O atoms in [Cu3(μ-O)3]2+-MOR and -MAZ significantly differ in reactivity toward methane.[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Author keywords” size=”size-sm” text_align=”text-left”][vc_column_text]Computational results,Desorption energy,DFT calculation,Experimental values,Methane activation,Methane hydroxylations,Methane partial oxidation,Water assisted[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Indexed keywords” size=”size-sm” text_align=”text-left”][vc_column_text]copper,DFT calculations on periodic systems,direct rebound mechanism,methane hydroxylation,water-assisted methanol desorption,zeolites[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Funding details” size=”size-sm” text_align=”text-left”][vc_column_text]This work was supported by KAKENHI Grant Nos. JP24109014 and JP15K13710 from the Japan Society for the Promotion of Science (JSPS) and the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT), the MEXT Projects World Premier International Research Center Initiative (WPI), Integrated Research Consortium on Chemical Sciences, and Elements Strategy Initiative to Form Core Research Center, the Cooperative Research Program Network Joint Research Center for Materials and Devices, and JST-CREST Grant No. JPMJCR15P5. M.H.M. gratefully acknowledges the Indonesia Endowment Fund for Education, Ministry of Finance of Indonesia, for scholarship support.[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”DOI” size=”size-sm” text_align=”text-left”][vc_column_text]https://doi.org/10.1021/acscatal.7b03389[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/4″][vc_column_text]Widget Plumx[/vc_column_text][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][/vc_column][/vc_row]