Simultaneous utilization of CO2 and potassium-rich biomass for the environmentally friendly production of potassium formate†

The C₁ chemical species, potassium formate (K(HCO₂)), known as a two-electron reducing agent, finds application in the synthesis of multi-carbon compounds, including oxalate, and plays a crucial role not only in the food and pharmaceutical industries but also across various sectors. However, the direct hydrogenation of CO₂ to produce K(HCO₂) remains a challenge. Addressing this issue, efficient production of K(HCO₂) is achieved by integrating CO₂ hydrogenation in a trickle-bed reactor using a heterogeneous catalyst with a novel separation method that utilizes potassium ions from biomass ash for formic acid derivative product isolation. Through alkaline-mediated CO₂ hydrogenation using N-methylpyrrolidine (NMPI), a concentrated 5 M NMPI solution of formic acid N-methylpyrrolidine complex ([NMPIH][HCO₂]) was formed, facilitating the synthesis of K(HCO₂) with over 99% purity via reaction with excess K ions contained within Bamboo ash. Notably, 80% of CO₂ was converted to formate ions, and NMPI was expected to be effectively recycled as it was completely removed during the evaporation process for K(HCO₂) separation. Additionally, this process yielded SiO₂ by-product particles with sizes ranging from 10 to 20 nm. This research highlights a novel strategy contributing to sustainable environmental management and resource recycling by effectively utilizing CO₂ as a valuable feedstock while concurrently producing valuable chemical compounds from waste materials.