Enabling Selective Dehydration of Methyl Lactate to Acrylates

Abstract

Dehydration of biomass-derived methyl lactate over NaY zeolite to acrylic acid and methyl acrylate is a promising route for the sustainable synthesis of acrylates. For commercial viability of the renewable chemistry, improvement of dehydration selectivity is necessary from the baseline performance of 60 to 90%. In the proposed reaction mechanism, dehydration occurs on the sodium acid sites, but side reactions occur on the in situ generated Brønsted acid sites (BAS) on the NaY catalyst. Introduction of a BAS-specific titrant can suppress side reactions and improve dehydration selectivity. While higher basicity favors stronger BAS adsorption and higher dehydration selectivity, steric limitations hinder BAS binding in the form of internal diffusion limitations and local steric interactions. Based on titrant basicity and steric limitations, multifunctional amines were demonstrated to afford the highest performance reported to date with a dehydration selectivity of 96% and a yield of 92%, exceeding the desirable values for commercial viability.