CO₂ feedstock obtained from point sources, such as chemical industries or fossil fuel-based power plants, typically contains gaseous contaminants such as SO_x, NO_x, H₂S, and COS, which can be detrimental to the catalysts used to electrochemically convert CO₂/CO into valuable fuels and chemicals. A significant suppression of C₂₊ products is observed even in the presence of 10 ppm of these impurities due to catalyst poisoning and a selectivity change. Hence, it is necessary to have an upstream cleaning process to maintain a high selectivity toward high value C₂₊ products and to reduce the operational costs associated with frequent catalyst regeneration or replacement. We present a comprehensive process model and technoeconomic analysis of an integrated large-scale two-step CO₂/CO electroreduction plant that produces C₂₊ products including ethylene, acetic acid, ethanol, and n-propanol, using blast furnace gas obtained from a steel manufacturing facility as feedstock. Detailed modeling and integration of the upstream cleaning units, CO₂/CO electrolyzers, and the downstream separation of gas/liquid products are performed using Aspen Plus. Our analysis shows that the large-scale two-step CO₂/CO electroreduction process is not profitable under the base case scenario and requires significant improvements in electrolyzer performance, reduction in capital costs, and favorable market conditions to improve the economics. The upstream cleaning units only contribute to ∼15% of the CAPEX and ∼8% OPEX of the entire plant, while the electrolyzers contribute to ∼63% of the total CAPEX and OPEX. A positive net present value ($54M), a payback time of 13 years, and an internal rate of return of 12.8% can be achieved when the electrolyzer capital cost is $10,000/m² (−50%) and electricity price is $20/MWh (−50%), with current densities of 750 mA/cm² (+50%) for both electrolyzers and cell voltages of 2.5 V (−17%) for CO₂R and 2.0 V (−20%) for COR electrolyzers, and when the product prices are 35% higher than the current market prices. Incorporating an energy-saving coelectrolysis process or integration into facilities that can directly utilize the products can accelerate the commercialization of the two-step CO₂/CO electroreduction process.

Electrochemical CO₂ reduction to CO offers a sustainable route for converting CO₂ into value-added chemicals and fuels. However, CO₂ streams derived from industrial sources often contain SO₂ impurities that severely poison conventional metal-based catalysts. Here, we report a nitrogen-doped carbon catalyst that exhibits pronounced tolerance and stability for CO₂-to-CO conversion in the presence of SO₂ (100–10,000 ppm). The catalyst maintains over 90% Faradaic efficiency toward CO during 8 h of electrolysis at −1.0 V vs RHE with 100 ppm of SO₂, whereas Ag foil electrodes undergo rapid deactivation. Density functional theory calculations combined with surface analyses indicate that weak SO₂ adsorption and the absence of stable sulfur accumulation on nitrogen-doped carbon strengthen its resistance to impurity-induced deactivation, in contrast to Ag catalysts that form Ag₂S. Gas-fed tests in a membrane electrode assembly (MEA) electrolyzer further confirm that nitrogen-doped carbon sustains high CO selectivity at elevated current densities, while Ag nanoparticles suffer irreversible sulfur poisoning. These results demonstrate that nitrogen-doped carbon is intrinsically resistant to SO₂-induced deactivation and highlight its potential as a robust catalyst for CO₂ electroreduction under impurity-containing conditions.

Electrochemical ammonia synthesis via the nitrogen reduction reaction (NRR) has been poised as one of the promising technologies for the sustainable production of green ammonia. In this work, we developed extensive process models of fully integrated electrochemical NH ₃ production plants at small scale (91 tonnes per day), including their techno-economic assessments, for (Li-)mediated, direct and indirect NRR pathways at ambient and elevated temperatures, which were compared with electrified and steam-methane reforming (SMR) Haber-Bosch processes. The levelized cost of ammonia (LCOA) of aqueous NRR at ambient conditions only becomes comparable with SMR Haber-Bosch at very optimistic electrolyzer performance parameters (FE > 80% at j ≥ 0.3 A cm ⁻²) and electricity prices (<$0.024 per kW h). Both high temperature NRR and Li-mediated NRR are not economically comparable within the tested variable ranges. High temperature NRR is very capital intensive due the requirement of a heat exchanger network, more auxiliary equipment and an additional water electrolyzer (considering the indirect route). For Li-mediated NRR, the high lithium plating potentials, ohmic losses and the requirement for H ₂, limits its commercial competitiveness with SMR Haber-Bosch. This incentivises the search for materials beyond lithium.