Electrochemical Conversion of CO2 to HCOOH at Tin Cathode: Development of a Theoretical Model and Comparison with Experimental Results

The electrochemical reduction of pressurized carbon dioxide at tin cathode is considered a very promising process for the production of formic acid. Here, the process was studied in an undivided cell with the aim of developing a simple theoretical model. First, a large series of polarization and electrolyses was performed in order to evaluate the kinetic of the process. According to the literature, experimental results can be described by a simple reaction mechanism, which involves the following key stages: (i) mass transfer of CO2 to the cathode; (i) its adsorption described by a Langmuir equation; (iii) the reduction of adsorbed CO2. A simple model was developed based on the cathodic conversion of pressurized CO2 to HCOOH and on its anodic oxidation. The theoretical model was in a good agreement with experimental results collected in this work and in previous ones and well described the effect of several operative parameters, including current density, pressure and kind of reactor.