Electrochemical Promotion of Catalysis: Investigation of the Polarization, Rate Oscillations, and Activation of Ethanol Reforming

Abstract

Energy demand and carbon emissions are equally important and interconnected concerns affecting the world. Sustainable energy sources offer promising solutions to these challenges. Generating energy by chemical transformation using catalytic reactions is one such source, especially for sustainable, electricity-driven technologies. Ethanol reforming reactions have received considerable attention from the research community; however, several barriers, such as catalyst deactivation, high reaction temperature, methanation, and coke formation, limit future upscaling and technology transfer to the commercial market. The electrochemical promotion of catalysis (EPOC) remains the focus of investigation because it may provide a solution for most of these limitations.

The first objective of this study involves a fundamental in-situ analysis of the role of polarization in the EPOC effect. Herein, CO adsorption over Pt was investigated via polarization modulation-infrared reflection-absorption spectroscopy because this apparatus enhances the sensitivity of species on the surface to identify those close to the reflective surface. This makes it a viable approach when considering the EPOC that takes place at the three-phase boundary, allowing researchers to follow the evolution of species on the surface. Using infrared spectroscopy, we demonstrate the shift in the binding energy of CO molecules under polarization for the first time. This supports the hypothesis asserting that the non-Faradaic effect on the catalyst leads to an enhancement in the binding energy of the reactant and intermediate species. These findings are not just foundational but directly instrumental in guiding the third objective of the study.

The second objective is devoted to a numerical modelling study that aims to clarify the contribution of the EPOC effect to the escalation or control of rate oscillations, which is the intrinsic quality of reactions like CO oxidation over Pt.

Thanks to the remarks of objective one on CO adsorption, the third objective investigates a processed-focused study on ethanol reforming. For the first time, EPOC is applied to ethanol reforming through partial oxidation (POX) and autothermal reforming (ATR) processes to control the activity and selectivity toward hydrogen, as well as to reinvestigate steam reforming. The steam reforming reaction exhibits the highest initial catalytic activity, although a strong deactivation of the catalyst occurs because of carbonaceous species deposition. Comparing POX and ATR, the latter presents the highest catalytic activity and the strongest electrochemical activation effect.

This research may provide insights into the unresolved debate on EPOC mechanisms and advance the study of new reaction systems to develop EPOC applications in sustainable low-carbon processes.