Catalytic amino acid production from biomass-derived intermediates
Amino acids are the building blocks for protein biosynthesis and find use in myriad industrial applications including use in food for humans, in animal feed, and as precursors for bio-based plastics, among others. Today, amino acids are primarily manufactured via microbial cultivation processes, which are costly, time consuming, and require extensive separations processes. As an alternative, chemo-catalytic approaches to produce amino acids from renewable feedstocks such as bio-based sugars could offer a rapid and potentially more efficient means of amino acid synthesis, but efforts to date have been limited by the development of facile chemistry and associated catalyst materials to selectively produce α-amino acids.
In this work, we report a heterogeneous catalyst that directly transforms lignocellulosic biomass-derived α-hydroxyl acids into α-amino acids, including alanine, leucine, valine, aspartic acid, tyrosine, and phenylalanine in high yields. The reaction follows a dehydrogenation-reductive amination pathway, with dehydrogenation as the rate-determining step. Ruthenium nanoparticles supported on carbon nanotubes (Ru/CNT) exhibit exceptional efficiency compared to catalysts based on other metals, due to the unique, reversible enhancement effect of NH3 on Ru in dehydrogenation. Based on the new catalytic system, a two-step chemical process was designed to convert glucose into alanine in 43% yield, comparable with the well-established microbial cultivation process, and therefore, the present strategy enables a new route for the production of amino acids from renewable feedstocks. Moreover, a conceptual process design employing membrane distillation to facilitate product purification is proposed and validated. Overall, this study offers a rapid and potentially more efficient chemical method to produce amino acids from woody biomass components.
This work is a result of collaboration with Prof. Ning Yan of National University of Singapore (NUS), who guided the research. The experiments were mainly conducted by Dr. Weiping Deng, who worked with Prof. Ning Yan for one year as a visiting scholar at NUS, and Yunzhu Wang (NUS). This work was financially supported by National Natural Science Foundation of China (91545203, 21690082 and 21473141), and the Fundamental Research Funds for the Central Universities (20720160029).
