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.