Alkaline Modified Mesoporous Silica Supported Ruthenium Catalyst for Improved α‐Amino Acid Synthesis

Abstract

AbstractAmino acids are a class of compounds with wide‐ranging applications. The synthesis of amino acids from biomass‐derived α‐keto acids and ammonia is a sustainable way but the unstable primary imine intermediates (R−C=NH) easily form oligomers. Herein, targeting this problem, alkaline modified mesoporous silica was employed as a support for ruthenium (Ru/M‐MCM‐41), which could be used as a bifunctional catalyst in the reductive amination of α‐keto acids to synthesize α‐amino acids. The incorporation of Sr improved the dispersion of Ru nanoparticles and enhanced metal‐support interactions via electron transfer from Sr to Ru, and the active Ru sites could efficiently hydrogenate primary imine intermediates to α‐amino acids, thus prohibiting the formation of oligomers. Moreover, the Sr‐dopant introduces base sites that could catalyze the hydrolysis of oligomers back to primary imine intermediates and finally hydrogenated to α‐amino acids. As a result, >99 % yield of glycine was achieved from glyoxylic acid over Ru/Sr‐MCM‐41, which is nearly three times that achieved over Ru/MCM‐41 (32.2 %).