Effect of CO₂ on the performance of an electrochemical hydrogen compressor

It is well known that CO₂ has a negative effect on the catalyst of the fuel cell causing inhibition in presence of H₂-CO₂ mixture. According to literature, CO formation is the responsible of catalyst inhibition. Since an electrochemical hydrogen compressor (EHC) has a working principle similar to a fuel cell, the presence of CO₂ can also be detrimental for the behavior of the compressor. In this work, the effect of CO₂ in binary H₂-CO₂ mixtures on the performance of an EHC has been investigated in detail. Both Reverse Water Gas Shift (RWGS) and electrochemical reduction of CO₂ may occur on the catalyst of an EHC. The main aim of the manuscript is to show RWGS is the most probable cause of catalyst inhibition. For a better understanding of the parameters involved in the catalyst inhibition in presence of a H₂-CO₂ mixture, different working conditions, viz. voltage and H₂ concentration, are applied to the compressor. These experiments show a faster catalyst inhibition for lower H₂ concentrations and lower voltages supplied. The temperature also plays an important role on the performance of the compressor. Indeed, since the RWGS is an endothermic reaction, the pollution of the catalyst is faster at higher temperatures. Recovery methods are also evaluated, and it was observed that air bleeding is most convenient because of its effectivity and recovery rate.