Efficient synthesis of bioetheric fuel additive by combining the reductive and direct etherification of furfural in one-pot over Pd nanoparticles deposited on zeolites

Furfuryl ethers have been considered to be a promising fuel additive. One step reduction etherification of furfural over supported Pd catalysts provides a facile way for the preparation of furfuryl ether. However, the preparation of a reusable Pd catalyst for reductive etherification remains to be a great challenge. In this study, a series of SiO₂ supported Pd catalysts with particle size ranging from 2.2 nm to 28 nm were prepared. Their textural properties and catalytic performance in furfural reductive etherification have been systematically studied. The results herein shed light on the particle size effect on the competition between hydrogenation/hydrogenolysis of C=O in furfural over Pd surface. We found out that Pd nanoparticles larger than 3 nm are preferred for one step reductive etherification. Based on this finding, we prepared a Pd/ZSM-5 bifunctional catalyst comprising Pd nanoparticles larger than 3 nm and decreased acidity in presence of amino organosilane, which served as a bifunctional catalyst succeeding in one-pot synthesis of ether via reductive-etherification and direct-etherification. This strategy showed significant advantage in efficiently converting furfuryl acohol, a major side-product, into ether, while suppressing the undesired side-reactions.