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Title: The characterization of BaCO{sub 3}-modified LaOF catalysts for the OCM reaction

Abstract

In this paper, BaCO{sub 3} is reported to be a good promoter for rhombohedral LaOF. With the addition of 5-20 mol% BaCO{sub 3}, methane conversion at 800{degrees}C was increased by ca. 40% with only slight loss in C{sub 2} selectivity. At CH{sub 4}: O{sub 2}: N{sub 2} = 2.6: 1:12 and a contact time of 0.6 g s ml{sup -1}, the methane conversion was 36.1%, while the C{sub 2} selectivity was 45.3%, giving a C{sub 2} yield of 16.4% over the 10 mol% BaCO{sub 3}/LaOF catalyst at 800{degrees}C. Comparing to LaOF, there was a 30% increase in C{sub 2} yield. Moreover, similar to the case of BaCO{sub 3}/LaOBr, the C{sub 2}H{sub 4}/C{sub 2}H{sub 6} ratio was enhanced by the presence of 5-20 mol% BaCO{sub 3}. The loaded barium was found to remain on the surface of the catalyst. XRD, O{sub 2}-TPD, and CO{sub 2}-TPD studies revealed that the BaCO{sub 3}/LaOF catalysts changed greatly in composition, surface site basicity, and active site concentration during OCM reaction. In situ Raman studies disclosed that at 700{degrees}C under CH{sub 4}/O{sub 2} (2.6/1), O{sub 2}-species were present on the 210 mol% BaCO{sub 3}/LaOF catalyst, while none was observed on LaOF. The authors conclude that themore » enhancement in methane conversion over the 5-20 mol% BaCO{sub 3}/LaOF catalysts was due to the generation of surface BaCO{sub 3} clusters on LaOF, which could decompose at the temperature range (700-850{degrees}C) adopted for OCM reaction to give BaO entities capable of activating O{sub 2} to adsorbed O{sub 2}{sup 2-}. 38 refs., 10 figs., 1 tab.« less

Authors:
; ;  [1]
  1. Hong Kong Baptist Univ., Kowloon (Hong Kong); and others
Publication Date:
OSTI Identifier:
563475
Resource Type:
Journal Article
Journal Name:
Journal of Catalysis
Additional Journal Information:
Journal Volume: 167; Journal Issue: 2; Other Information: PBD: 15 Apr 1997
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; 40 CHEMISTRY; BARIUM CARBONATES; CATALYTIC EFFECTS; STRUCTURAL CHEMICAL ANALYSIS; LANTHANUM COMPOUNDS; OXYFLUORIDES; METHANE; DIMERIZATION; TRIGONAL LATTICES; CHEMICAL REACTION YIELD; X-RAY DIFFRACTION; RAMAN SPECTROSCOPY; HETEROGENEOUS CATALYSIS; OXIDATION; DESORPTION

Citation Formats

Au, C T, Zhang, Y Q, and He, H. The characterization of BaCO{sub 3}-modified LaOF catalysts for the OCM reaction. United States: N. p., 1997. Web. doi:10.1006/jcat.1997.1577.
Au, C T, Zhang, Y Q, & He, H. The characterization of BaCO{sub 3}-modified LaOF catalysts for the OCM reaction. United States. https://doi.org/10.1006/jcat.1997.1577
Au, C T, Zhang, Y Q, and He, H. 1997. "The characterization of BaCO{sub 3}-modified LaOF catalysts for the OCM reaction". United States. https://doi.org/10.1006/jcat.1997.1577.
@article{osti_563475,
title = {The characterization of BaCO{sub 3}-modified LaOF catalysts for the OCM reaction},
author = {Au, C T and Zhang, Y Q and He, H},
abstractNote = {In this paper, BaCO{sub 3} is reported to be a good promoter for rhombohedral LaOF. With the addition of 5-20 mol% BaCO{sub 3}, methane conversion at 800{degrees}C was increased by ca. 40% with only slight loss in C{sub 2} selectivity. At CH{sub 4}: O{sub 2}: N{sub 2} = 2.6: 1:12 and a contact time of 0.6 g s ml{sup -1}, the methane conversion was 36.1%, while the C{sub 2} selectivity was 45.3%, giving a C{sub 2} yield of 16.4% over the 10 mol% BaCO{sub 3}/LaOF catalyst at 800{degrees}C. Comparing to LaOF, there was a 30% increase in C{sub 2} yield. Moreover, similar to the case of BaCO{sub 3}/LaOBr, the C{sub 2}H{sub 4}/C{sub 2}H{sub 6} ratio was enhanced by the presence of 5-20 mol% BaCO{sub 3}. The loaded barium was found to remain on the surface of the catalyst. XRD, O{sub 2}-TPD, and CO{sub 2}-TPD studies revealed that the BaCO{sub 3}/LaOF catalysts changed greatly in composition, surface site basicity, and active site concentration during OCM reaction. In situ Raman studies disclosed that at 700{degrees}C under CH{sub 4}/O{sub 2} (2.6/1), O{sub 2}-species were present on the 210 mol% BaCO{sub 3}/LaOF catalyst, while none was observed on LaOF. The authors conclude that the enhancement in methane conversion over the 5-20 mol% BaCO{sub 3}/LaOF catalysts was due to the generation of surface BaCO{sub 3} clusters on LaOF, which could decompose at the temperature range (700-850{degrees}C) adopted for OCM reaction to give BaO entities capable of activating O{sub 2} to adsorbed O{sub 2}{sup 2-}. 38 refs., 10 figs., 1 tab.},
doi = {10.1006/jcat.1997.1577},
url = {https://www.osti.gov/biblio/563475}, journal = {Journal of Catalysis},
number = 2,
volume = 167,
place = {United States},
year = {Tue Apr 15 00:00:00 EDT 1997},
month = {Tue Apr 15 00:00:00 EDT 1997}
}