Aqueous phase conversion of CO2 into acetic acid over thermally transformed MIL-88B catalyst

Sustainable production of acetic acid is a high priority due to its high global manufacturing capacity and numerous applications. Currently, it is predominantly synthesized via carbonylation of methanol, in which both the reactants are fossil-derived. Carbon dioxide transformation into acetic acid is highly desirable to achieve net zero carbon emissions, but significant challenges remain to achieve this efficiently. Herein, we report a heterogeneous catalyst, thermally transformed MIL-88B with Fe-0 and Fe3O4 dual active sites, for highly selective acetic acid formation via methanol hydrocarboxylation. ReaxFF molecular simulation, and X-ray characterisation results show a thermally transformed MIL-88B catalyst consisting of highly dispersed Fe-0/Fe(II)-oxide nanoparticles in a carbonaceous matrix. This efficient catalyst showed a high acetic acid yield (590.1 mmol/g(cat).L) with 81.7% selectivity at 150 degrees C in the aqueous phase using LiI as a co-catalyst. Here we present a plausible reaction pathway for acetic acid formation reaction via a formic acid intermediate. No significant difference in acetic acid yield and selectivity were noticed during the catalyst recycling study up to five cycles. This work is scalable and industrially relevant for carbon dioxide utilisation to reduce carbon emissions, especially when green methanol and green hydrogen are readily available in future. Carbon dioxide conversion into chemicals is essential for carbon capture and utilization. Here, the authors present a novel iron-based catalyst, synthesized from the thermal treatment of a parent metal-organic framework (MIL-88B), to produce a dual-active site for carbon dioxide reduction into acetic acid.

Automated summary

A novel heterogeneous catalyst, thermally transformed MIL-88B with Fe-0 and Fe3O4 dual active sites, was reported for highly selective production of acetic acid via methanol hydrocarboxylation. The catalyst showed high yield (590.1 mmol/g(cat).L) and selectivity (81.7%) of acetic acid, and maintained stable performance during recycling. This work is of great significance for reducing carbon emissions by utilizing carbon dioxide.