Recently, Sn catalysts, which have been utilized for formate production, has shown the potential for production of syngas, due to even distribution of nano-sized tin oxides with conductive materials. However, fundamental challenges of liquid-phase reaction have been facing hurdles in current densities for scaling up electrochemical CO2 reduction process. The application of a gas diffusion layer has enhanced conversion efficiency and rate, owing to increased mass transport of CO2. Here, we propose a membrane-based reactor where an Sn integrated permeable CNT hollow fiber membrane (Sn-CHM) was prepared to achieve cost-effective and highly efficient syngas production. CO2 flow rates and pH of electrolytes were selected as operational parameters to maximize performances, and CO2 was purged inside the hollow fiber (O.D: 1 mm, I.D: 550 μm). The results indicated that selectivity and current density for syngas production were peaked at 5 sccm in 0.1 M KHCO3, with all tested potentials. Further investigation for the effect of pH showed that current densities improved as increase of pH, maintaining H2/CO ratio of 0.5–3.0, which is suitable for the post F-T process. The maximum partial current density of 104.8 mA/cm2 for syngas production was achieved with H2/CO ratio of 0.42 at CO2 flow rate of 5 sccm and –0.95 V (vs. RHE) in 5 M KOH. This value is the highest reported for electrochemical syngas production from CO2 under ambient conditions, even in comparison with that of noble metals.

Permeable CNT hollow fiber membrane as a facile strategy for electrocatalytic syngas production from CO2

2019 Fall National Meeting

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