One-pot conversion of furfural to gamma-valerolactone in the presence of multifunctional zirconium alizarin red S hybrid

A multifunctional Zr-containing catalyst (FM-Zr-ARS) was successfully synthesized by a modulated hydrothermal synthesis route. Systematic characterization results supported the presence of robust porous inorganic-organic frameworks stabilized by the strong coordination interaction of Zr 4+ with oxygen-rich functional groups in Alizarin red S (ARS). Moreover, the -O-Zr-O- network in the FM-Zr-ARS structure formed a rich content of acid-base sites. In addition, the inherent sulfonic groups in ARS made the FM-Zr-ARS hybrids possess Brønsted acid sites. Therefore, under the synergistic catalysis of the multiple functional sites, FM-Zr-ARS showed remarkably high catalytic activity for γ-valerolactone (GVL) production from levulinate esters and furfural. Finally, 72.4 % and 97.7 % yields of GVL were obtained in the conversion of furfural and ethyl levulinate, respectively, after 8 h of reaction at 433 K. On the basis of the role of different functional sites, a plausible catalytic mechanism was presented for the conversion of biomass-derived furfural to GVL.