Methanol and DME are highly efficient fuels and relevant building blocks that can be synthesized by CO₂ hydrogenation. While several alternatives for methanol production by CO₂ hydrogenation have already been developed at a commercial scale, DME production is still based on methanol dehydration. In this sense, the development of bifunctional methanol synthesis/dehydration catalysts is a clear opportunity for the simultaneous coproduction of methanol and DME in a single-step process. Although a few alternatives for DME-methanol coproduction have been proposed, either they need external fuels or refrigerants, or part of the CO₂ used as raw material is purged, resulting in a loss of methanol and DME yields. This work presents a novel thermally self-sufficient process that hydrogenates CO₂ into methanol and DME in a single reactor at 100 % yield (only water as a byproduct at 0.94 kg_water/kg_product), that only consumes air, cooling water (0.006 m³ _water/kg_products) and electricity (net CO₂ emissions of −1.20 or 0.64 kg_CO2eq/kg_products when the plant is operated with green or grey electricity, respectively). The innovative design, based on the combination of a top-divided wall column, an integrated heat network, and limited pressure drop in the reaction-separation loop, results in a thermally self-sufficient process that uses only 0.76 kWh per kg products.

The hydrogenation of CO₂ to methanol is a technology that converts a greenhouse gas into a valuable chemical compound that efficiently stores energy. Several alternatives to perform this process have been proposed, but they are either not thermally self-sufficient and depend on using external fuel, or the power usage per ton of methanol is insufficiently optimized, or part of the raw materials must be purged and therefore there is a loss of methanol yield. This original study aims to develop a novel thermally self-sufficient process for e-methanol production (at practically 100% yield along with water by-product of 0.37 kg_water/kg_product) that only uses green electricity. The main innovation of the process is an effective thermally self-sufficient heat-integration scheme that only needs 0.0059 m³_water/kg_methanol combined with using a dividing wall column to recover the unreacted CO₂ and obtain high purity methanol. In addition, the pressure reduction in the reaction-separation loop is limited to the pressure drop of the circuit to minimize the overall green electricity use to only 656 kWh per ton methanol, resulting in net CO₂ emissions of −1.13 kg_CO2/kg_MeOH or 0.78 kg_CO2/kg_MeOH when the plant operates with green or grey hydrogen and electricity, respectively. Finally, the operating pressure in the reactor is optimized at 65 bar to minimize the total annualized cost.