Compact reactor for Fischer–Tropsch synthesis based on hierarchically structured Co catalysts: Towards better stability

• Efficient Co catalyst on 3-D structured carbon nanofiber (CNF)/carbon felt (CF) as compact F–T synthesis reactor.
• Improved stability by coated thin layer on CNFs.
• High thermal conductivity.
• High activity and selectivity.

A compact reactor for Fischer–Tropsch (F–T) synthesis based on hierarchically structured Co catalysts has been developed. The SiO2 coated carbon nanofiber (CNF)/carbon felt (CF) has several advantages, such as high surface area, low pressure drop, high thermal conductivity and good mass transport properties. CNFs were grown on the microfibers of CF, which greatly increased the surface area of the composite. An in situ sol–gel method has been developed to coat one thin layer of SiO2 to form CNF/CF@SiO2 core shelled tubes. The efficient 3-D thermal conductive network in the composite provided a relatively uniform temperature gradient during the F–T synthesis without adding any diluents. The prepared Co/(CNF/CF@SiO2) catalysts have higher activity and C5+ selectivity. The catalyst stability is also greatly enhanced by manipulating the Co-support interface by means of the coated SiO2 layer on CNFs. Reduction–oxidation (Redox) cycles indicate that the SiO2 layer decreases the oxidation potential of the Co nanoparticles, with enhanced catalytic stability as a result.

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