In-situ water separation enhanced methyl glycolate oxidation to methyl glyoxylate by catalytic membrane reactor

The selective oxidation of methyl glycolate by oxygen is a green route for the synthesis of methyl glyoxylate, which however faces great challenges like the consecutive hydrolysis reaction between methyl glyoxylate and by-product water. Herein, we fabricated an in-situ water separation catalytic membrane reactor (CMR) to suppress the hydrolysis of methyl glyoxylate, which can promptly and preferentially remove water from the reaction system by a hydrophilic NaA membrane. The MoO₃@NaA CMR achieved a high methyl glyoxylate selectivity of 84.0 % at 260 °C and 2 bar, being 32.4 % higher than that of the conventional fixed-bed reactor (FBR), while the methyl glycolate conversion was almost the same for both modes. Moreover, the deactivation of the MoO₃ catalyst caused by water in CMR was also greatly inhibited, exhibiting excellent stability as compared to FBR. The in-situ water separation strategy in this work contributed to a new concept to improve the selectivity of easily hydrolyzable products.