Synthesis gas (syngas) is a mixture of H 2 , CO and occasionally CO 2 , whose main application is as a building block of chemical compounds. The desired product dictates the syngas characteristics, which are also affected by the employed syngas synthesis technology. In this work, we study the process of producing syngas under desired specifications while consuming CO 2 in the synthesis. We propose a superstructure that includes seven reforming technologies for the syngas production, as well as a variety of auxiliary units to control the final composition of the syngas. Each potential solution is assessed, in terms of the economic and environmental performance, by the Total Annualized Cost (TAC) and the Global Warming Potential (GWP) indicator. As the problem statement involves discrete decision, we use disjunctions to model the system. The resulting MINLP multi-objective problem is solved by the epsilon constraint method. Results show that at low syngas H 2 /CO ratios and pressures, dry methane reforming (DMR) is capable of net consuming CO 2 . Partial Oxidation (POX) is the technology that exhibits the minimum TAC, although shows the maximum value for the GWP.Synergistic combination of two processes allows reducing the cost and CO 2 -equivalent emissions through the pairing of DMR and bi-reforming (BR) and BR with steam methane reforming (SMR). Furthermore, increasing the CO 2 content in the syngas at a fixed (H 2 -CO 2 )/(CO + CO 2 ) ratio proves that TAC and GWP decrease as the CO 2 /CO ratio increases.

Copper catalysts are attractive candidates for Hg-free vinyl chloride monomer (VCM) production via acetylene hydrochlorination due to their non-toxic nature and high stability. However, the optimal architecture for Cu-based catalysts at the nanoscale is not yet fully understood. To address this gap, the metal precursor and the annealing temperature are modified to prepare copper nanoparticles or single atoms, either in chlorinated or ligand-free form, on an unmodified carbon support. Evaluation in the reaction reveals a remarkable convergence of the performance of all materials to the stable VCM productivity of the single-atom catalyst. In-depth characterization by advanced microscopy, quasi in situ and operando spectroscopy, and simulations uncover a reaction-induced formation of low-valent, single atom Cu(I)Cl site motif, regardless of the initial nanostructure. Various surface oxygen groups promote nanoparticle redispersion by stabilizing single-atom CuCl x species. The anchoring site structure does not strongly influence the acetylene adsorption energy or the crucial role they play in stabilizing key reaction intermediates. A life-cycle assessment demonstrates the potential environmental benefits of copper catalysts over state-of-the-art alternatives. This work contributes to a better understanding of optimal metal speciation and highlights the sustainability of Cu-based catalysts for VCM production.

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Electro-fuels are seen as a promising alternative to curb carbon emissions in the transport sector due to their appealing properties, similar to those of their fossil counterparts, allowing them to use current infrastructure and state-of-the-art automotive technologies. However, their broad implications beyond climate change remain unclear as previous studies mainly focused on analyzing their carbon footprint. To fill this gap, here, we evaluated the environmental and economic impact of Fischer–Tropsch electro-diesel (FT e-diesel) synthesized from electrolytic H 2 and captured CO 2 . We consider various power (wind, solar, nuclear, or the current mix) and carbon sources (capture from the air (DAC) or a coal power plant) while covering a range of impacts on human health, ecosystems, and resources. Applying process simulation and life cycle assessment (LCA), we found that producing e-diesel from wind and nuclear H 2 combined with DAC CO 2 could reduce the carbon footprint relative to fossil diesel, leading to burden-shifting in human health and ecosystems. Also, it would incur prohibitive costs, even when considering externalities (i.e., indirect costs of environmental impacts). Overall, this work highlights the need to embrace environmental impacts beyond climate change in the analysis of alternative fuels and raises concerns about the environmental appeal of electro-fuels.