Low Temperature Direct Conversion of Methane using a Solid Superacid

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