High thermal conductive core-shell structured Al2O3@Al composite supported cobalt catalyst for Fischer-Tropsch synthesis

- Al2O3@Al composite is prepared via NaOH corrosion method.
- The Al2O3@Al composite has a macro-mesoporous structure.
- The thermal conductive coefficient of Co/Al2O3@Al is 13-98 times of Co/Al2O3.
- Co/Al2O3@Al exhibits high CO conversion, C5+ selectivity and low CH4 selectivity.

High thermal conductive Al2O3@Al composite synthesized via metallic Al powders corrosion method has been applied as support for preparing Co/Al2O3@Al catalyst for high exothermic Fischer-Tropsch synthesis. The prepared Al2O3@Al composite is a hierarchical macro-mesoporous structure and consist of two parts, namely the inner metallic Al and the outer Al2O3 with two kinds of morphologies. Increasing the concentration of the corrosive NaOH or extending the corrosion time could increase the specific surface area of the composite. For the prepared Co/Al2O3@Al, Co3O4 phase is located on the outer plate-like Al2O3 layer. The Co/Al-0.03-20 possesses higher CO conversion and C5+ selectivity due to the appropriate cobalt reducibility, dispersion and high thermal conductivity. The thermal conductive coefficient of Co/Al2O3@Al catalysts is 13-98 times of conventional Co/Al2O3. Compared to Co/Al2O3, the Co/Al2O3@Al shows higher CO conversion and C5+ selectivity as well as lower CH4 and CO2 selectivity, which is attributed to the macro-mesoporous structure and high thermal conductivity. In addition, because of the high thermal conductivity, no heat disperser should be used and a homogeneous temperature gradient maintains within the catalyst bed for Co/Al2O3@Al.

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