Economically viable electrocatalytic ethylene production with high yield and selectivity

Abstract

Electrocatalytic semihydrogenation of acetylene provides a clean pathway to produce ethylene (C 2 H 4 ), one of the most widely used petrochemical feedstocks, but its performance is still well below that of the thermocatalytic route, leaving its practical feasibility questionable. Here our techno-economic analysis shows that this process becomes pro table if the Faraday e ciency (FE) exceeds 85% at a current density of 0.2 A cm −2 . As a result, we design a Cu nanoparticle catalyst with coordinatively unsaturated sites to steer the reaction towards these targets. Remarkably, our electrocatalyst synthesized on gas diffusion layer-coated carbon paper enables a high C 2 H 4 yield rate of 70.15 mmol mg −1 h −1 and a FE of 97.7% at an industrially relevant current density of 0.5 A cm −2 . Combined characterizations and calculations reveal that such performance can be attributed to a favorable combination of a higher energy barrier for coupling of active hydrogen atoms (H*) and weak absorption of *C 2 H 4 . The former serves to suppress the competitive hydrogen evolution reaction, whereas the latter avoids overhydrogenation and C-C coupling. Further life cycle assessment evidences the economic feasibility and sustainability of the process. Our work suggests a way towards rational design and manipulation of nanocatalysts that could nd wider and greener catalytic applications.

Designed Nanomaterials for Electrocatalytic Organic Hydrogenation Using Water as the Hydrogen Source

“…The obtained ED-Cu NPs exhibit excellent performance toward C 2 H 2 semihydrogenation to C 2 H 4 with 90% FEs over a wide range of current densities from 0.1 to 1.0 A cm –2 in a flow reactor . Both the FE of C 2 H 4 and the conversion of C 2 H 2 display no obvious changes during a 54 h continuous test at 0.2 A cm –2 (Figure f), implying the robust durability of ED-Cu.…”

“…The electrocatalytic semihydrogenation of coal-derived acetylene (C 2 H 2 ) with water offers a promising room-temperature petroleum-independent route to produce C 2 H 4 . , However, the unclear target of the C 2 H 2 -to-C 2 H 4 process and the unsatisfactory yield and FE at an industrial level current density impede practical applications. Thus, we perform a preliminary techno-economic analysis (TEA) of this process and determine that a ≥85% C 2 H 4 FE at a current density of ≥0.2 A cm –2 will be profitable based on the electricity price of 0.03 US$ per kWh (Figure a) . To meet this goal, four factors should be considered to choose a suitable electrode: (i) low activation energy for water dissociation and small Gibbs free energy (Δ G H* ) for H* formation; (ii) high energy barrier for H* self-coupling; (iii) easy desorption of C 2 H 4 to avoid overhydrogenation; and (iv) enhanced mass transfer to elevate the local concentration of C 2 H 2 .…”

“…(f) Continuous tests of C 2 H 4 production. Adapted with permission from ref . Copyright 2023 Springer Nature.…”

“…Meanwhile, the electronic and geometric structures of nanomaterials are easy to modify to match more transformations. The reaction selectivity can be substantially controlled to a large extent by nanomaterials rather than potential or current density, which is conducive to practical applications . Furthermore, nanostructured electrodes have been extensively studied in recent electrocatalytic hydrogen evolution reactions via water splitting, ,, providing an important guarantee to access sufficient H* by controlling its formation.…”

Ab initio study for late steps of CO2 and CO electroreduction: from CHCO* toward C2 products on Cu and CuZn nanoclusters

“…20 Recently, a work has reported that acetylene provides a direct pathway to produce ethylene on Cu nanoparticles with faradaic efficiency of about 97.7%. 21 In addition to the identification of intermediates that could distinguish reaction mechanisms, it was also suggested that undercoordinated sites could favor ethanol production, 20 which could guide the design of catalysts with specific sites that favor the formation of one or another intermediate. Therefore, the study of the late steps (after C-C coupling) of the mechanism of the C 2 products could be crucial to understanding how to improve the selectivity of the products.…”