A Discussion on the Unique Features of Electrochemical Promotion of Catalysis (EPOC): Are We in the Right Path Towards Commercial Implementation?

Abstract

The phenomenon of “Non-Faradaic Electrochemical Modification of Catalytic Activity (NEMCA)” or “Electrochemical Promotion of Catalysis (EPOC)” has been extensively studied for the last decades. Its main strength, with respect to conventionally promoted catalytic systems, is its capability to modify in-situ the activity and/or selectivity of a catalyst by controlling the supply and removal of promoters upon electrical polarization. Previous reviews have summarized the main achievements in this field from both the scientific and technological points of view. However, to this date no commercial application of the EPOC phenomenon has been developed, although numerous advances have been made on the application of EPOC on catalyst nanostructures (closer to those employed in conventional catalytic systems), and on the development of scaled-up reactors suitable for EPOC application. The main bottleneck for EPOC commercialization is likely the choice of the right chemical process. Therefore, from our point of view, future efforts should focus on coupling the latest EPOC advances with the chemical processes where the EPOC phenomenon offers a competitive advantage, either from an environmental, a practical or an economic point of view. In this article, we discuss some of the most promising cases published to date and suggest future improvement strategies. The considered processes are: (i) ethylene epoxidation with environmentally friendly promoters, (ii) NOx storage and reduction under constant reaction atmosphere, (iii) CH4 steam reforming with in-situ catalyst regeneration, (iv) H2 production, storage and release under fixed temperature and pressure, and (v) EPOC-enhanced electrolysers.

Electrochemical control of the RWGS reaction over Ni nanoparticles deposited on yttria stabilized zirconia

“…21,33,[35][36][37] In contrast to the traditionally used organometallic pastes, the main advantage of free-standing NPs includes the uniform metal dispersion on the solid electrolyte as well as thin and highly porous catalytic films. 26 In this regard, the used sample was characterized through scanning electron microscopy (SEM). Fig.…”

“…21 More specifically, the EPOC effect, also known as non-faradaic electrochemical modification of catalytic activity (NEMCA) is a highly utilized tool in heterogeneous catalysis over the past 40 years. [22][23][24][25][26][27] This effect is commonly studied with a simple and straightforward experimental set up involving three metal electrodes deposited onto a solid electrolyte/ion conductor as shown in Fig. S1.…”

Electrochemical promotion of ethanol partial oxidation and reforming reactions for hydrogen production

“…SR of methanol can be the most relevant case to ethanol reforming as both feedstocks categorized as primary alcohols, and the studied catalytic systems were Ni and Cu both supported on KβAl2O3 [38,39]. Most of these studies have shown the interest of EPOC in the H2 production technology 4 as reviewed in recent publications [44,45]. Nonetheless, the commercial implantation of the EPOC phenomenon has not been developed yet, being the poorly dispersed materials on the electrode, the reactor configuration or the study of the adequate processes the main drawbacks [45].…”

“…Most of these studies have shown the interest of EPOC in the H2 production technology 4 as reviewed in recent publications [44,45]. Nonetheless, the commercial implantation of the EPOC phenomenon has not been developed yet, being the poorly dispersed materials on the electrode, the reactor configuration or the study of the adequate processes the main drawbacks [45].…”

Short Term Silver Electrode Microstructure Changes Under Epoxidation Conditions for Solid Oxide Electrolysis Cells

“…9,12,13 This process has been shown to increase the EO selectivity with relatively small (μA/cm 2 to mA/cm 2 ) applied currents. 3,14,15 Previous studies have examined the effect of varying current density on selectivity at different applied currents and demonstrate that a higher applied current increases selectivity and total catalytic rate. 16 The proper molar ratio of ethylene to oxygen in the feed gas is not well agreed upon, with studies finding evidence that both ethylene-rich and oxygen-rich feeds produce a higher selectivity.…”