Catalytic conversion of biomass-derived compounds to high added value products using an acid treated natural mordenite

Abstract

Herein, the mordenite catalyst TECHΝOSA-H2 that originates from volcanic soils in Greek islands is utilized for the synthesis of ethers and acetals from renewable raw materials. Di-furfuryl ether and furfuryl ethyl ether are used in perfumery and fuels, respectively, and are usually produced by employing either homogeneous catalysts or heterogeneous catalysts which however may lead to undesirable polymer products. Using TECHNOSA H2 we achieved yields in di-furfuryl ether and furfuryl ethyl ether 30% and 60%, respectively, in 3 h and 150 °C. We also report the synthesis of citral propylene glycol acetal and citral diethyl acetal, two important compounds in perfumery industry whose industrial synthesis often requires homogeneous catalysts while with TECHNOSA-H2 50% yields are achieved in 20 min and mild temperatures. The nature of the active sites of TECHNOSA-H2 was inspected by its application to relevant test reactions revealing that Brønsted acidity dominates in this catalyst. To that end, the one-step isomerization of a-pinene oxide to campholenic aldehyde and the one-step cyclization of citronellal to isopulegol in 10min were achieved. Finally, the shape selectivity of the catalyst was examined, proving TECHNOSA-H2 to be selective between the (E)- and (Z)- isomers of Citral. Based on our findings, TECHNOSA-H2 applications vary and include acetalization, isomerization and etherification reactions, as well as reactions where shape selectivity between reactants is desired.