Single-site ruthenium catalyst supported on zeolite for CO₂ hydrogenation to methyl formate.

Abstract

Technologies for the transformation of atmospheric CO₂ to useful chemicals, such as formic acid (FA), are essential to combatting excessive fossil fuel use and will need to be implemented on large scale. However, hydrogenation of CO₂ to (base-free) FA is challenging for heterogeneous catalysts, due to the requirement for low temperatures enforced by the entropically unfavorable reaction of gases. By coupling CO₂ hydrogenation to esterification, methyl formate (MF) can be prepared as a promising alternative platform chemical. Herein, a robust, heterogeneous single-metal-site catalyst was prepared and shown to achieve methanol hydrocarboxylation rates superior to nanoparticle catalysts (up to 18.3 ± 0.6 mmol hour^-1 [Formula: see text]) while maintaining very high selectivity to MF (≥95%). Characterization reveals isolated, monodisperse Ru-nitrosyl complexes bound to three O-atoms of the zeolite framework, and the robust catalyst formed achieves a cumulative turnover number of more than 3500 over eight cycles. This work pushes the boundaries of supported single-site catalysts in CO₂ utilization.