《Table 1 Surface area and amount of Brnsted and Lewis acid sites on Zr PO after evacuation at 100°C,

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《Direct Conversion of Glucose to 5-Hydroxymethylfurfural over Zirconium Phosphate Catalyst in a Biphasic System》

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The types of the acid sites on Zr PO catalyst were determined by the Py-FTIR spectroscopic study of the catalyst，with the spectra in the range of 1 430 cm-1-1 560 cm-1 shown in Figure 4.There were three bands in this region.The one at 1 542 cm-1 was the characteristic band of Br?nsted acid sites，which could occur due to the presence of Zr-OH and P-OH groups on the surface.Another peak near 1 490 cm-1 could be attributed to the adsorption of pyridine on both Br?nsted and Lewis sites at the same time.The peak at about 1 450 cm-1 was assigned to the adsorption of pyridine on the Lewis acid sites，which could be caused by the unsaturated-coordinate Zr.The weak sites were defined as ones from which pyridine was removed by evacuation at 200°C；the medium acidity strength corresponded to evacuation between 200°C and 400°C and the strong sites still adsorbed pyridine molecules after evacuation at 400°C.Quantification of weak，medium and strong acid sites was obtained from the spectra of adsorbed pyridine using the expressions referred to in the literature[26]，with the data summarized in Table 1.