Direct conversion of methane to value-added hydrocarbons using hybrid catalysts of Ni/Al2O3 and K–Co/Al2O3

Abstract

The direct conversion of methane (CH4) to value-added hydrocarbons (C2+) was studied using a hybrid catalyst, consisting of Ni/Al2O3 as the first catalyst layer to convert CH4 to carbon monoxide, and K-Co/Al2O3 as the second catalyst layer to convert carbon monoxide to C2+. Interestingly, this hybrid catalyst worked effectively at a relatively low temperature (490 °C) compared to other catalysts in the oxidative coupling of methane (over 700 °C). The effects of different operating conditions at atmospheric pressure were investigated. The highest C2+ yield at 4.3% C2+ yield was achieved at a reactor temperature of 490 °C. The K promoter played an essential role in enhancing the C2+ formation. A proposed mechanism was described for the reaction using the hybrid catalyst. Furthermore, a time-on-stream test of the hybrid catalyst over 24 h showed that the stability of the catalyst was excellent during the test.