Novel efficient process for methanol synthesis by CO2 hydrogenation

Methanol is an alternative fuel that offers a convenient solution for efficient energy storage. Complementary to carbon capture activities, significant effort is devoted to the development of technologies for methanol synthesis by hydrogenation of carbon dioxide. While CO2 is available from plenty of sources, cheap sources of H2 are less frequently found. An additional source of hydrogen at industrial scale is the wet hydrogen by-product of chlorine production. This study is the first to propose an efficient process for methanol synthesis by CO2 hydrogenation using wet hydrogen by-product from chlor-alkali production. A key feature of this novel process is the use of a stripping unit where the wet hydrogen flows in counter-current mode with the condensed methanol–water mixture resulting from the high-pressure low-temperature separator after the reaction. This operation has a double positive effect, as it removes the CO/CO2 from the methanol–water mixture thus allowing a complete recycle of CO2 and avoiding its presence in the product, while also removing the water from the wet hydrogen thus avoiding the negative impact of adding water on the equilibrium conversion – with consumption figures of 550 kWh electricity and 0.48–1.16 ton steam per ton methanol.