Na2WO4/Mn supported on all-silica delaminated zeolite for the optimal oxidative coupling of methane via the effective stabilization of tetrahedral WO4: Elucidating effects of support precursors with different crystal structures, Al-addition, and morphologies

Sangseo Gu, Jisong Kang, Taehee Lee, Jaehee Shim, Jae Wook Choi, Dong Jin Suh, Hyunjoo Lee, Chunjae Yoo, Hionsuck Baik, Jungkyu Choi, Jeong Myeong Ha

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4 Citations (Scopus)

Abstract

The oxidative coupling of methane (OCM) converts this abundant natural feedstock into value-added products and is typically performed in the presence of catalysts such as SiO2-supported Na2WO4/Mn to suppress the undesired deep oxidation affording CO and CO2. Currently, the phase transformation of SiO2 supports to α-cristobalite is known to be important for securing high OCM activity, although the underlying reasons of this influence remain debatable. Herein, Na2WO4/Mn catalysts supported on several SiO2-based materials including conventional amorphous SiO2 and crystalline zeolites were prepared to close the above knowledge gap and thus promote the design of more efficient OCM catalysts. The best support was identified as calcined D-ITQ-1, which is a well-developed delaminated zeolite with a thin basal all-silica nanosheet structure facilitating the transition to the α-cristobalite phase. The corresponding catalyst retained high activity over 100 h and exhibited one of the highest yields (25.8%) of C2+ hydrocarbons (paraffins and olefins) reported for dopant-free Na2WO4/Mn/SiO2 catalysts to date. The results of XRD, Raman, and 29Si NMR indicated that this high performance can be ascribed to the stabilization of tetrahedral WO4 units due to the transition from uncalcined silica to α-cristobalite. Thus, the present work advances our understanding of structural phase transitions and the concomitant formation of the desired active species in Na2WO4/Mn/SiO2 catalysts and paves the way to the design of better catalysts through the modification of zeolite supports.

Original languageEnglish
Article number141057
JournalChemical Engineering Journal
Volume457
DOIs
Publication statusPublished - 2023 Feb 1

Bibliographical note

Funding Information:
This research was supported by the C1 Gas Refinery Program (2018M3D3A1A01018004) and the Technology Development Program to Solve Climate Changes (2020M1A2A2079798) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT of Republic of Korea. The authors thank the Korea Basic Science Institute (KBSI) Seoul Center (Seoul, Republic of Korea) for the HR TEM images.

Funding Information:
This research was supported by the C1 Gas Refinery Program (2018M3D3A1A01018004) and the Technology Development Program to Solve Climate Changes (2020M1A2A2079798) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT of Republic of Korea. The authors thank the Korea Basic Science Institute (KBSI) Seoul Center (Seoul, Republic of Korea) for the HR TEM images.

Publisher Copyright:
© 2022

Keywords

  • Catalyst
  • Delaminated ITQ-1
  • NaWO
  • Oxidative coupling of methane
  • Silica support
  • Zeolite

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry
  • General Chemical Engineering
  • Industrial and Manufacturing Engineering

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