Phosphate-modified ZSM-5 catalyst converting beverage wastewater to 5-hydroxymethylfurfural and electrochemical upgrading

Abstract Converting sugars in beverage wastewater into 5-hydroxymethylfurfural (5-HMF) provides a sustainable waste valorisation pathway. A heterogeneous phosphate-modified ZSM-5 catalyst was examined as an alternative to the conventional homogeneous sulfuric acid catalyst for selective 5-HMF production from beverage wastewater under hydrothermal conditions. Treating ZSM-5 with KH2PO4 introduces surface phosphate species while preserving zeolite crystallinity and the coexistence of acidic and basic active sites. The KH2PO4-modified ZSM-5 catalyst delivered a 5-HMF yield of 23.6%, compared to 18.0% for neat ZSM-5 when treating beverage wastewater at 160 °C for 45 min. The improved performance is attributed to a favourable acid-base synergy that suppressed side reactions. The 5-HMF-containing post-reaction stream was then fed into an alkaline electrolyser. Electrolysis delivered a high hydrogen Faradaic efficiency (98 ± 2%) and complete 5-HMF conversion into products including 2,5-FDCA (~30% yield), levulinic acid and formic acid. This integrated approach demonstrates the potential to simultaneously valorise beverage wastewater and produce hydrogen and value-added chemicals, offering an alternative to conventional wastewater treatment and disposal.