1,2-Propylene Glycol and Ethylene Glycol Production From Lignocellulosic Biomass

Abstract Hydrogenolysis of mono- and polysaccharides as well as sugar alcohols enables a direct access to industrially relevant glycols 1,2-propylene glycol and ethylene glycol. Mechanistic insights have established a reaction sequence of dehydrogenation, retro aldol cleavage and rehydrogenation of sugar alcohol substrates. A combination of metal and base catalysis proved efficient to facilitate this sequence. Both combinations of supported metal catalysts with molecular bases and multifunctional solid catalysts possessing both functionalities were considered. Despite the development of several very promising catalyst systems, some challenges for industrial application remain. Especially to name are catalyst stability and recyclability, undesired byproduct formation and overall carbon balances. Herein, the current state of the art in terms of mechanistic understanding, catalyst design and structure-activity relations is presented together with some insight on factors the named challenges.