Fraunhofer UMSICHT has developed a cost-competitive catalytic technology for the carbon-chain elongation (CCE) of renewable short-chain alcohols and ketones. CCE makes specific primary or secondary alcohols with medium chain length. The achievable chain length and the type of alcohol depend on the employed feedstock. Several promising feedstocks are available due to the existence and current revival of fermentation technologies, in particular for fuels and green solvents in the context of circular economy.
To illustrate the potential of CCE, ethanol was converted to a mixture of ethyl-branched and linear primary alcohols in the range of C6-C10. The latter was transformed with citric and succinic acid to esters and successfully tested as plasticizers. Lab tests have shown that short primary alcohols can be upgraded by CCE to crude sugar-surfactants (APG), replacing unsustainable alcohols sourced from crude oil or coconut and palm kernel oil. Branched secondary alcohols with 11 to 22 carbon atoms are made in a similar fashion by CCE and a high selectivity is achievable.