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Title: Partial oxidation of methane to synthesis gas over MgO- and SiO{sub 2}-supported rhodium catalysts

Abstract

The partial oxidation of methane over MgO- and SiO{sub 2}-supported rhodium catalysts was investigated, using a CH{sub 4}/O{sub 2} mixture with a molar ratio of 2.1/1 as feed gas. At 750 C and atmospheric pressure, the 1% Rh/MgO catalyst exhibited a very high stability at the high gas hourly space velocity of 720,000 ml/g h, its catalytic activity and selectivity remaining constant and high after an induction time up to 100 h of reaction. In contrast, the 1% Rh/SiO{sub 2} catalyst deactivated rapidly. To explain the above results, the reaction behaviors of CH{sub 4} and CH{sub 4}/O{sub 2} (2/1) over the oxidized catalysts 1% Rh(O)/MgO and 1% Rh(O)/SiO{sub 2} were studied in a pulse microreactor. No carbon deposition occurred during the reaction of CH{sub 4} with the MgO-supported rhodium catalyst, even after the catalyst was almost completely reduced. In contrast, a notable amount of surface carbon was generated during the reaction of CH{sub 4} with the SiO{sub 2}-supported rhodium catalyst, even after the catalyst was almost completely reduced. In contrast, a notable amount of surface carbon was generated during the reaction of CH{sub 4} with the SiO-supported rhodium catalyst. During the reaction of CH{sub 4}/O{sub 2} (2/1) over the oxidizedmore » catalysts, the rhodium oxide supported on SiO{sub 2} was easily reduced by CH{sub 4}, while the reduction of rhodium oxide supported on MgO occurred with some difficulty. This implies much stronger interactions between rhodium oxide and MgO than between the former and SiO{sub 2}. Temperature-programmed reduction experiments also revealed much stronger interactions between rhodium and magnesium oxide and that two kinds of rhodium compounds were present in the oxidized MgO-supported rhodium catalyst. X-ray powder diffraction enabled the authors to identify Rh{sub 2}O{sub 3} and MgRh{sub 2}O{sub 4} in precalcined 10% Rh(O)/SiO{sub 2} and 10% Rh(O)/MgO, respectively. It is suggested that the strong interactions between rhodium and magnesium oxide (especially the formation of MgRh{sub 2}O{sub 4}) are responsible for the high stability of the MgO-supported rhodium catalysts.« less

Authors:
;  [1]
  1. State Univ. of New York, Amherst, NY (United States). Dept. of Chemical Engineering
Publication Date:
OSTI Identifier:
687734
Resource Type:
Journal Article
Journal Name:
Journal of Catalysis
Additional Journal Information:
Journal Volume: 186; Journal Issue: 1; Other Information: PBD: 15 Aug 1999
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; 10 SYNTHETIC FUELS; METHANE; PARTIAL OXIDATION PROCESSES; SYNTHESIS GAS; MAGNESIUM OXIDES; SILICON OXIDES; CATALYTIC EFFECTS; RHODIUM; DEACTIVATION

Citation Formats

Wang, H.Y., and Ruckenstein, E. Partial oxidation of methane to synthesis gas over MgO- and SiO{sub 2}-supported rhodium catalysts. United States: N. p., 1999. Web. doi:10.1006/jcat.1999.2535.
Wang, H.Y., & Ruckenstein, E. Partial oxidation of methane to synthesis gas over MgO- and SiO{sub 2}-supported rhodium catalysts. United States. doi:10.1006/jcat.1999.2535.
Wang, H.Y., and Ruckenstein, E. Sun . "Partial oxidation of methane to synthesis gas over MgO- and SiO{sub 2}-supported rhodium catalysts". United States. doi:10.1006/jcat.1999.2535.
@article{osti_687734,
title = {Partial oxidation of methane to synthesis gas over MgO- and SiO{sub 2}-supported rhodium catalysts},
author = {Wang, H.Y. and Ruckenstein, E.},
abstractNote = {The partial oxidation of methane over MgO- and SiO{sub 2}-supported rhodium catalysts was investigated, using a CH{sub 4}/O{sub 2} mixture with a molar ratio of 2.1/1 as feed gas. At 750 C and atmospheric pressure, the 1% Rh/MgO catalyst exhibited a very high stability at the high gas hourly space velocity of 720,000 ml/g h, its catalytic activity and selectivity remaining constant and high after an induction time up to 100 h of reaction. In contrast, the 1% Rh/SiO{sub 2} catalyst deactivated rapidly. To explain the above results, the reaction behaviors of CH{sub 4} and CH{sub 4}/O{sub 2} (2/1) over the oxidized catalysts 1% Rh(O)/MgO and 1% Rh(O)/SiO{sub 2} were studied in a pulse microreactor. No carbon deposition occurred during the reaction of CH{sub 4} with the MgO-supported rhodium catalyst, even after the catalyst was almost completely reduced. In contrast, a notable amount of surface carbon was generated during the reaction of CH{sub 4} with the SiO{sub 2}-supported rhodium catalyst, even after the catalyst was almost completely reduced. In contrast, a notable amount of surface carbon was generated during the reaction of CH{sub 4} with the SiO-supported rhodium catalyst. During the reaction of CH{sub 4}/O{sub 2} (2/1) over the oxidized catalysts, the rhodium oxide supported on SiO{sub 2} was easily reduced by CH{sub 4}, while the reduction of rhodium oxide supported on MgO occurred with some difficulty. This implies much stronger interactions between rhodium oxide and MgO than between the former and SiO{sub 2}. Temperature-programmed reduction experiments also revealed much stronger interactions between rhodium and magnesium oxide and that two kinds of rhodium compounds were present in the oxidized MgO-supported rhodium catalyst. X-ray powder diffraction enabled the authors to identify Rh{sub 2}O{sub 3} and MgRh{sub 2}O{sub 4} in precalcined 10% Rh(O)/SiO{sub 2} and 10% Rh(O)/MgO, respectively. It is suggested that the strong interactions between rhodium and magnesium oxide (especially the formation of MgRh{sub 2}O{sub 4}) are responsible for the high stability of the MgO-supported rhodium catalysts.},
doi = {10.1006/jcat.1999.2535},
journal = {Journal of Catalysis},
number = 1,
volume = 186,
place = {United States},
year = {1999},
month = {8}
}