Finding an alternative source for products produced in oil refineries, which include transportation fuels and functional chemicals, such as aromatics, is not straightforward. To secure the supply of these base chemicals, the input of oil refineries should gradually shift from crude oil to CO₂, biomass, plastic, and agricultural waste.¹ CO₂, obtained from point sources would be an ideal starting material to produce useful chemical products. A promising strategy to produce higher-order chemicals from CO₂ is by combining two catalytic processes in two reactors.³

Here, we developed a two-stage lab-scale reaction process to convert CO₂ via CH₄ into aromatics (Fig. 1). A Ni-based catalyst is used to obtain CH₄, which is fed into a second reactor to produce benzene in the so-called methane dehydroaromatization (MDA) process. One of the major challenges concerning the implementation of MDA in the two-stage reactor is the presence of left-over reactants (CO₂ and H₂) and reaction products (e.g. steam and CO) from the first reactor bed. Through thermodynamic calculations and experimental screening, we found the ideal conditions to perform the two-stage reaction. These insights can aid in the development of a novel pathway to obtain aromatics from CO₂.

References

(1)         Vogt, E. T. C.; Weckhuysen, B. M. The Refinery of the Future. Nature 2024, 629, 295–306. https://doi.org/10.1038/s41586-024-07322-2.

(2)         Vogt, C.; Monai, M.; Kramer, G. J.; Weckhuysen, B. M. The Renaissance of the Sabatier Reaction and Its Applications on Earth and in Space. Nat. Catal. 2018, 2, 188–197. https://doi.org/10.1038/s41929-019-0244-4.

(3)         Garg, S.; Xie, Z.; Chen, J. G. Tandem Reactors and Reactions for CO₂ Conversion. Nat. Chem. Eng. 2024, 1, 139–148. https://doi.org/10.1038/s44286-023-00020-2.

Angela Melcherts has been a PhD Candidate in the Inorganic Chemistry and Catalysis group at Utrecht University since 2020. Her research focuses on understanding metal-support interaction in Ni-based catalysts for the CO2 hydrogenation reaction towards methane. The reaction of CO2 to methane was used as a first step for an integrated process to further valorize CO2-waste gas streams to produce aromatics.