Hydrogenation to convert CO2 to C1 chemicals: Technical comparison of different alternatives by process simulation

Carbon dioxide (CO2) conversion by catalytic reaction with hydrogen to produce different C1 chemicals is a promising strategy in view of the development of a sustainable chemical industry. In this work, two CO2 hydrogenation routes are investigated in detail, respectively syngas and formic acid syntheses. Starting from published experimental reaction data, simulation models based on a kinetic analysis were developed and implemented in Aspen Plus process simulator. The two processes are analyzed according to a number of selected technological indicators, comprising CO2 conversion, specific H2 consumption, product yield, energy duties, and carbon emissions. To extend our study, three additional CO2 conversion pathways are considered, respectively methanol, methane, and urea syntheses, whose technological performances were retrieved from similar studies available in the scientific literature. Under the assumption that H2 is available from renewable sources, our results highlight that CO2 conversion routes towards fuel compounds (ie, syngas and methane) look particularly appealing from the energy balance point of view. If non-renewable energy is used to produce H2, the actual environmental benefits (in terms of net CO2 emissions) strongly depend on the country-specific carbon intensity for electricity generation.