Catalytic Conversion of Glucose to 5-Hydroxymethyl-furfural with a Phosphated TiO2 Catalyst

Nanosized phosphated TiO2 catalysts with different phosphate contents were synthesized and tested for the conversion of glucose to 5-hydroxymethylfurfural. The resulting materials were characterized by using N-2-adsorption, XRD, inductively coupled plasma atomic emission spectroscopy, X-ray spectroscopy, TEM, temperature-programmed desorption of ammonia, and FTIR spectroscopy of pyridine adsorption techniques to determine their structural, bulk, surface, and acid properties. We found that TiO2 nanoparticles catalyzed this reaction under mild conditions in a water-butanol biphasic system. The incorporation of phosphorus into the TiO2 framework remarkably enhances the target product selectivity, which is ascribed to increased surface area, enhanced acidity, as well as thermal stability resulting from the Ti-O-P bond formation. Under optimal reaction conditions, phosphated TiO2 was found to exhibit excellent catalytic performance, which resulted in 97% glucose conversion and 81% HMF yield after 3 h of reaction at 175 degrees C. More importantly, the catalyst showed good stability and could be reused for several reaction cycles.