Thermally self-sufficient process for single-step coproduction of methanol and dimethyl ether by CO2 hydrogenation

Abstract

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 DMEmethanol 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 kgwater/kgproduct), that only consumes air, cooling water (0.006 m3 water/kgproducts) and electricity (net CO2 emissions of − 1.20 or 0.64 kgCO2eq/kgproducts 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.