Dual-bed strategies to improve hydrocarbon yields in the oxidative coupling of methane

Document Type

Article

Publication Date

12-31-1994

Abstract

The performances of Li-containing catalysts have been compared in the oxidative coupling of methane (OCM), Li/Sn/MgO was found to be superior in activity almost equal to Li2CO3/ MgO in selectivity. Using these catalysts, attempts were made to further increase the C2+ yield of the OCM process. Blank reactor experiments on the oxidation of ethane, and catalytic OCM experiments with SiC in the post-catalyst volume showed that the role of gas phase reactions in the formation of carbon oxides is typically minimal. However, the use of a presumably 'inert' second bed of SiC, while not increasing selectivities, can increase C2+ yields. Ga-doped MFI zeolites are known to be good ethane dehydrogenation catalysts. The possibility of OCM using a 5 wt.-% Ga-doped ZSM-5 zeolite (MFI-5) was examined, and it was found that MFI-5 showed some OCM activity. The addition of some oxygen was necessary to convert ethane to aromatics at higher temperatures. An attempt was then made to integrate the OCM aromatization functions in a single reactor. Intimate mixtures of Li/MgO MFI-5 gave low activity selectivity no aromatization. However, using a Ga/ MFI catalyst bed on top of a Li/Sn/MgO catalyst again increased overall C2+ yields, this time accompanied by aromatics formation. Possible explanations for these phenomena are offered. © 1994.

Publication Source (Journal or Book title)

Applied Catalysis B, Environmental

First Page

71

Last Page

88

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