Methane conversion into value-added chemicals is one of the most important challenges facing researchers today. Direct conversion offers a unique opportunity to convert methane into value- added chemicals at temperatures lower than those at which reforming is carried out. These processes do not require the addition of a co-reactant. One reaction of interest is based on superacids, which can catalyze methane oligomerization at temperatures as low as 300 oC: CH4 --&gt; CnHm + H2 Despite the success in activating methane, gas and liquid phase superacids pose significant separation problems, which will require a solid catalyst. AlBr3 is a strong Lewis acid that is known for its use in Friedel Crafts reactions including: alkylation and acylation. These can be supported on solid inorganic supports like SiO2, Al2O3, or even zeolites to avoid the separation problems associated with liquid catalysts. H-ZSM-5 is a well-known shape-selective acid catalyst with strong Brønsted acid sites. Its activity in acid-catalyzed reactions, including methane aromatization, is well documented. In the current study, Al2Br6 is anchored to the surface of H-ZSM5 using a vapor phase grafting technique, in which Al2Br6 vapor reacts with the surface hydroxyl groups of ZSM-5. The acidity of the zeolite is greatly enhanced by aluminum bromide, confirmed by NH3-TPD and pyridine-DRIFTS. This solid acid catalyst tested here, “ABZ-5”, is active for the oligomerization of methane as low as 300 oC (below). Though deactivation is significant and methane conversions have been studied here at levels of ~1%, the results here show that a Br-based solid superacid is active for the oligomerization of methane (Fig.1). We think that this is the first demonstration of this class of catalysts. These catalysts may find applications in variety of acid-catalyzed reactions such as alkylation, isomerization, and oligomerization.

Methane to value-added chemicals using a solid superacid

2019 Spring National Meeting

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