The electrochemical reduction of carbon dioxide (CO 2 RR) to chemical feedstocks, such as ethylene (C 2 H 4 ), is an attractive means to mitigate emissions and store intermittent renewable electricity. Much research has focused on improving CO 2 electrolysis cell efficiency; less attention has been paid to the downstream purification of outlet product streams. In this work, we model the use of mature downstream separation technologies as part of the overall production of polymer-grade C 2 H 4 from CO 2 . We find that CO 2 removal is the most energy-intensive downstream separation step. We identify opportunities to reduce separation energies to ∼22 GJ/tonne C 2 H 4 through necessary improvements in C 2 H 4 selectivity (>57%), cathodic CO 2 conversion (>80%), and CO 2 crossover (0 mol CO 2 /mol e − ). This work highlights the influence of cell performance parameters on downstream separation costs and motivates the development of new, efficient separation processes better suited to the distinctive outlet streams of CO 2 electrolyzers.

Adiabatic operation of catalytic fixed-bed reactors for Oxidative Coupling of Methane (OCM) has been simulated using a detailed microkinetic and reactor model. For several catalysts (1%wtSr/La2O3, 10%wtLa-20%wtSr/CaO, 4%wtSn-2%wtLi/MgO and 12%wtMn-20%wtNa2WO4/SiO2), diverse in activity and selectivity towards C2+ products, operating conditions have been determined that maximize C2+ yield at low inlet temperature T0 (<< 923 K). A prior analysis of light-off curves served as a guideline for optimal operating temperature ranges for each catalyst. Imposing a maximum temperature in the reactor (T max ≤ 1273 K) suggested a limit for the catalytic performances, corresponding to 13% CH4 conversion and 61% C2+ selectivity at the reactor outlet for an active (T0= 723 K) Sr/La2O3 catalyst, and an improved 19% CH4 conversion and 82% C2+ selectivity for a less active (T0= 853 K) NaMnW/SiO2 catalyst. The obtained

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Oxidative coupling of methane is a low‐cost alternative for ethylene production. However, its high exothermicity, complex reaction network, and low selectivity to C2 products require more in‐depth analysis for economically viable process implementation. Microkinetic modeling enables assessment of operating conditions and catalyst properties on the overall performance via elementary gas‐phase and catalytic reactions. The know‐how to reproduce and interpret experimental kinetic data, especially the role of highly reactive intermediate species, is crucial for correct reaction network determination. Once the catalyst descriptors, physical catalyst properties, and operating conditions are determined and optimized, next catalyst generations can be developed tailored to the process implementation.

Intrinsic kinetics study of steam methane reforming (SMR) was performed on two different systemscommercial Ni-based pellet catalyst and Pt/Ni/Al2O3 structured plate catalyst. Experiments were carried out in the absence of external mass transfer resistance, and temperature 500–575 °C, pressure 2.5–7.5 bar, and H2O/CH4 reactant ratio range of 3–5 mol/mol. Reactors operated in the integral mode, and it was shown that both systems could be described by the same kinetics, based on Langmuir–Hinshelwood mechanism. In the case of plate catalyst, the regeneration treatment after deactivation led to platinum particle redispersion, which further influenced the values of the pre-exponential factors, whereas the activation energy values remained unchanged. Comparison of the two catalyst systems was made based on the active metal content, and it was shown that the catalytic activity of the Pt/Ni/Al2O3 plate catalyst after the second regeneration treatment was 8 times of that observed for the Ni-based pellet catalyst.