Selective tandem catalysis for the synthesis of 5-hydroxymethylfurfural from glucose over in-situ phosphated titania catalysts: Insights into structure, bi-functionality and performance in flow microreactors

5-Hydroxymethylfurfural (HMF) synthesis from glucose over in-situ phosphated titania catalysts is presented. Phosphates were incorporated into framework forming a titanium phosphate surface layer, where the coordinatively unsaturated tetrahedral TiO 4 units act as water-tolerant Lewis acid site (LAS) and adjacent protonated Brønsted (BAS), together Lewis-Brønsted pairs at molecular-level proximity. Glucose turnover HMF selectivity enhanced due to rapid fructose transfer LAS BAS for its dehydration HMF, facilitating liberation another turnover. Reactions in water-2-methyltetrahydrofuran biphasic system packed-bed microreactors gave 66% yield (from 1 M 150 °C), space time about two orders of magnitude higher than that batch literature work. Phosphate leaching catalyst rather limited, whereas deactivated mainly by humin deposition could be regenerated calcination. • Phosphated 2 prepared phosphation sol-gel method. formed proximity on catalyst. conversion pairs. Enhanced yields realized flow microreactors. strongly embedded endow good hydrothermal stability.