Electrochemical valorisation of glycerol

Abstract

The worldwide glycerol stocks are increasing; to make the biodiesel industry sustainable economically, this chemical could be used as a secondary primary raw material. Electric energy or hydrogen and added-value-chemical cogeneration becomes more and more an important research topic for increasing economical and industrial interests towards electrochemical technologies. Studies on glycerol electrooxidation for fuel or electrolysis cell applications are scarce. The valorisation of glycerol is generally performed by organic chemistry reactions forming, for example, esters, glycerol carbonates, ethers, acetals or ketals. Glycerol oxidation is made up of complex pathway reactions that can produce a large number of useful intermediates or valuable fine chemicals with presently limited market impact due to expensive production processes. Many of these chemical oxidation routes lead to significant amounts of undesired by-products, and enzymatic processes are limited. Converse to classical heterogeneous processes, electrocatalytic oxidation processes can be tuned by controlling the nature, composition and structure of the electrocatalyts as well as the electrode potential. Such control may lead to very high selectivity and activity, avoiding or limiting product separation steps. The coupling of glycerol oxidation to produce chemicals with the oxygen reduction reaction in a fuel cell or water reduction reaction in an electrolysis cell on Pt-free catalysts results either in coproduction of electrical energy or hydrogen for energy storage.