Abstract
Electrolysis at intermediate temperatures (100-600°C) is promising because high reaction rates and high product selectivity can be achieved simultaneously during CO2 reduction. However, intermediate temperature electrolysis has rarely been reported owing to electrolyte limitations. Here, solid acid electrolysis cells (SAECs) were adopted for electrochemically reducing CO2. Carbon monoxide, methane, methanol, ethane, ethylene, ethanol, acetaldehyde and propylene were produced from CO2 and steam, using Cu-containing composite cathodes at 220°C and atmospheric pressure. The results demonstrate the potential of SAECs for producing valuable chemical feedstocks. At the SAEC cathode, CO2 was electrochemically reduced by protons and electrons. The product selectivity and reaction rate were considerably different from those of thermochemical reactions with gaseous hydrogen. Based on the differences, plausible reaction pathways were proposed.