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Low temperature direct conversion of methane using a solid superacid

Kanitkar, Swarom, Carter, James H., Hutchings, Graham J., Ding, Kunlun and Spivey, James J. 2018. Low temperature direct conversion of methane using a solid superacid. ChemCatChem 10 (21) , pp. 5033-5038. 10.1002/cctc.201801310
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Abstract

The direct conversion of methane to higher hydrocarbons and hydrogen can be catalyzed using “superacids”: nCH4→CnHm+xH2. The first report of catalytic oligomerization of methane using superacids was that of Olah et al., who demonstrated the superacidity of FSO3H−SbF5, which is a liquid. More recently, Vasireddy et al. showed that gas‐phase HBr/AlBr3 was an active superacid. The only reported solid superacid for methane oligomerization is sulfated zirconia (SZ). Here, we report a new class of Br‐based solid superacids, AlBrx/H‐ZSM‐5 (“ABZ‐5”, x=1 or 2). ABZ‐5 is based on gas‐phase HBr/AlBr3, with the objective of synthesizing a heterogeneous analogue of the gas‐phase superacid HBr/AlBr3. The results show that ABZ‐5 is significantly more active than SZ. Perhaps more significantly, results here show methane conversions of ∼1 % at 300 °C using ABZ‐5. By comparison with SZ, 350 °C is the lowest temperature reported in the literature at which measurable conversions are shown, and the corresponding methane conversions were <0.15. Here, we demonstrate direct conversion of methane using a solid superacid catalyst, AlBrx/H‐ZSM‐5. This solid catalyst is synthesized using a vapor‐phase process in which AlBr3 vapor is grafted on to solid H‐SZM‐5. This catalyst is characterized using NH3‐TPD, XRD, and DRIFTS. Hydrocarbon products observed in the temperature range of 200–400 °C include both C2–C6 hydrocarbons and aromatics.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Chemistry
Cardiff Catalysis Institute (CCI)
Publisher: Wiley: 12 months
ISSN: 1867-3880
Date of First Compliant Deposit: 12 November 2018
Date of Acceptance: 9 September 2018
Last Modified: 31 Dec 2018 22:40
URI: http://orca.cf.ac.uk/id/eprint/116659

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