Identifying the preferential pathways of CO2 capture and hydrogenation to methanol over an Mn(i)–PNP catalyst: a computational study

Abstract

CO₂ hydrogenation to CH₃OH is a crucial conversion for several purposes. Density functional theory (DFT) studies have been performed to explore the mechanistic pathways of newly reported CO₂ capture and hydrogenation to methanol. The present study describes the multistep transformation of CO₂ to methanol. In this case we have introduced 2-amino-1-propanol to capture CO₂ and hydrogenation of the CO₂ captured product (oxazolidinone) in the presence of an active Mn(I)–PNP based catalyst. All the plausible pathways for oxazolidinone hydrogenation to methanol have been explored in detail. Here, hydride and proton transfer steps are very important for oxazolidinone hydrogenation, whereas heterolytic H₂ cleavage is the most important step for the regeneration of the catalyst. Our detailed study shows that C–N bond hydrogenation followed by C–O and CO bond hydrogenations or C–O bond hydrogenation followed by C–N and CO bond hydrogenations are the most favourable pathways for oxazolidinone hydrogenation to methanol with a total reaction free energy barrier of 36.9 kcal mol⁻¹ for both the pathways in the presence of a Mn(I)–PNP catalyst.