Protein‐rich biomass provides a valuable feedstock for the chemical industry. This Review describes every process step in the value chain from protein waste to chemicals. The first part deals with the physicochemical extraction of proteins from biomass, hydrolytic degradation to peptides and amino acids, and separation of amino acid mixtures. The second part provides an overview of physical and (bio)chemical technologies for the production of polymers, commodity chemicals, pharmaceuticals, and other fine chemicals. This can be achieved by incorporation of oligopeptides into polymers, or by modification and defunctionalization of amino acids, for example, their reduction to amino alcohols, decarboxylation to amines, (cyclic) amides and nitriles, deamination to (di)carboxylic acids, and synthesis of fine chemicals and ionic liquids. Bio‐ and chemocatalytic approaches are compared in terms of scope, efficiency, and sustainability.

A palladium based catalytic system was developed to decarboxylate glutamic acid and pyroglutamic acid to bio-based 2-pyrrolidone in aqueous media at 250 °C and under an inert atmosphere.

While protein-rich biomass waste is nowadays mainly used for animal feed, conversion of its amino acid constituents to nitrogenous chemicals is a potential higher value route. To that end, the hydrogenation of amino acids to amino alcohols was studied in this work. Using a bimetallic Rh-MoOx/SiO2 catalyst, glutamic acid was for the first time hydrogenated to the aminodiol in high yield. By minimizing partial reduction and consecutive hydrogenolysis, and by suppressing the competitive cyclization to pyroglutamic acid (and derivatives thereof), glutamidiol was obtained in 77% yield at 70 bar H2 and 80 °C. High yields (typically > 80%) and selectivities were also achieved for most other natural amino acids, except for the S-containing amino acids 2 cysteine and methionine, which act as catalyst poisons. This limitation was overcome by applying a simple oxidation step with performic acid prior to the hydrogenation. The system was applied successfully to a mixture of amino acids obtained by hydrolysis of pre-oxidized bovine serum albumin. Amino alcohols were produced with high overall conversion (> 90%) and selectivity (88%) without the need for an intermediate, expensive and difficult separation step. The reaction proceeds with very high atom economies for both carbon and nitrogen, and generates only water as a by-product.

Glutamic acid was successfully converted into dimethyl glutarate and trimethylamine by a Pt based reductive deamination at 225 °C in methanol.

Amino acids have huge potential as platform chemicals in the biobased industry. Pd-catalyzed decarboxylation is a very promising route for the valorization of these natural compounds derived from protein waste or fermentation. We report that the highly abundant and nonessential amino acid L-proline is very reactive in the Pd-catalyzed decarboxylation. Full conversions are obtained with Pd/C and different Pd/MeO x catalysts; this allowed the identification of the different side reactions and the mapping of the reaction network. Due to the high reactivity of pyrrolidine, the selectivity for pyrrolidine was initially low. By carefully modifying Pd/ZrO 2 with Pb in a controlled mannervia two incipient wetness impregnation stepsthe selectivity increased remarkably. Finally, a thorough investigation of the reaction parameters resulted in an increased activity of this modified catalyst and an even further enhanced selectivity under a low H 2 pressure of 4 bar at 235 °C in water. This results in a very selective and sustainable production route for the highly interesting pyrrolidine.

Graphical representation of Lewis acid catalyzed ammonolysis of polyamide 66.

Bio-based N-alkyl-2-pyrrolidones were successfully synthesized, starting from glutamic acid and simple carbonyl compounds, by Pd-catalyzed reductive N-alkylation and decarboxylation.