Fabrication of ordered mesoporous POMs/SiO2-NH2 nanofibers for production of DFF from 5-HMF for cellulose wastewater resource recovery.

Abstract 5-hydroxymethylfurfural (5-HMF) is a biomass cellulose platform product that can be transformed into the valuable resource 2,5-diformylfuran (DFF). Polyoxometalates (POMs) have important applications in resource recovery technologies and cellulose wastewater treatment. Ordered mesoporous H5PMo10V2O40/SiO2-NH2 (wt%) nanofibers (HPMoV/meso-SiO2-NH2 (wt%)) were synthesized by the combining in-situ fabrication and electrospinning techniques, using H5PMo10V2O40 (HPMoV) and organic-silica as precursors. Aiming the recovery and transformation of 5-HMF, aerobic oxidation of 5-HMF was explored using these nanofibers as catalysts, while the best yield of DFF (90.0%) was obtained upon HPMoV/meso-SiO2-NH2 (23%) nanofibers after 8 h at 120 °C using oxygen (1.0 MPa). The selectivity to DFF was improved by changing the hydrophilicity of the HPMoV@SiO2 nanofibers to hydrophobicity by modifying SiO2 nanofibers with -NH2R compared to mesoporous SiO2 nanofibers, which allowed the formed DFF to be isolated. In the recycling test, HPMoV@SiO2-NH2 showed good performance, and no leaching of active sites from SiO2-NH2 due to the interactions between them occurred after 10 cycles. The production of DFF from the real cellulosic wastewater was obtained with 118 % yield based on 5-HMF conversion by HPMoV/meso-SiO2-NH2 (23) and oxygen, which was contributed to the one-pot conversion of sugar, furan and 5-HMF in the wastewater.