Energy Efficient Formaldehyde Synthesis by Direct Hydrogenation of Carbon Monoxide in Functionalized Metal–Organic Frameworks

Abstract

Formaldehyde (CH2O) is a highly versatile platform chemical with an annual production of over 30 megatons. The current most widely used industrial method for formaldehyde synthesis is very energy intensive and plagued with significant exergy losses. We propose a highly efficient heterogeneous nanoporous catalyst capable of direct hydrogenation of CO to CH2O followed by condensation of CH2O from a mixture of CO and H2, which are noncondensable gases. The key to this synthesis is a Lewis pair (LP) functionalized metal–organic framework (MOF) heterogeneous porous catalyst. We have computed reaction pathways, barriers, and uncertainties for CO hydrogenation on a LP functionalized MOF using various density functional theory (DFT) methods and high-level ab initio methods. We have assessed the uncertainties in the energetics inherent in the DFT functionals. We predict that the thermodynamics of CH2O synthesis will be enhanced relative to gas phase synthesis and more importantly, will not be equilibrium limited because the barrier to product desorption from the MOF is much lower than the barrier for the reverse reaction. Hence, the product will be continuously removed from the process, facilitating very high overall conversion rates. Our proposed process will dramatically improve the sustainability of CH2O synthesis.