Bifunctional Lewis and Brønsted acidic zeolites permit the continuous production of bio-renewable furanic ethers

The catalytic valorisation of bio-renewable feedstock often relies upon multi-stage processing of highly-functionalised substrates, resulting in selectivity and processs engineering challenges. Herein, we demonstrate that a bifunctional zeolitic material, containing both Lewis and Brønsted acid sites in a single catalytic material, permits the continuous production of bio-renewable furanic ethers, such as (butoxy)methyl furan, which possess potential as fuel additives. In contrast to mono-functional catalysts and physical mixtures thereof, the bifunctional Sn- and Al-containing BEA zeolite results in uniquely-high levels of activity, selectivity and stability. Optimal results were obtained over a bifunctional catalyst containing 2 wt% Sn and 0.5 wt% Al, prepared by modified solid state incorporation, which was highly selective (>75%) to the desired ether for over 100 h on stream, and for over 3000 substrate turnovers.