Efficient synthesis of furfural over mZSM-5@SO42-/mSiO2 core–shell catalyst by targeted regulating B/L acids

[Display omitted] •A core–shell catalyst mZSM-5@SO42-/mSiO2 composed of mZSM-5 core and SO42-/mSiO2 shell was prepared by the soft template method.•The proximity and hierarchy of acidic sites within the core–shell catalyst were constructed to regulate the transport of key intermediates.•The acid ratio was adjusted by introducing the Brønsted acid sites directly into the shell while the core active sites remained unchanged.•The reaction path and mechanism of core–shell catalyst in the preparation of furfural from xylose were revealed. A core–shell catalyst mZSM-5@SO42-/mSiO2 composed of mZSM-5 core and SO42-/mSiO2 shell was prepared by the soft template method. Core-shell structure could promote the building of Brønsted -Lewis (B-L) acids interface and significantly improve the synergistic effect of B-L. In this paper, the Brønsted/Lewis (B/L) of mZSM-5@SO42-/mSiO2 was targeted regulating by innovatively introducing Brønsted acid (BA) sites into the shell. The optimal mZSM-5@SO42-/mSiO2 catalyst (B/L = 0.142) could achieve 72.1 % furfural yield at 140 ℃ for 1 h. In addition, 70.2 % furfural yield could be obtained after the catalyst was recycled and regenerated for 5 times. Combining In-situ IR and 13C NMR, the reaction path was revealed in detail: xylose was first isomerized to xylulose and then dehydrated to furfural. This paper provides a research idea for the directional regulation of dual active sites of cascade reaction catalysts.