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Catalytic fast pyrolysis of cellulose to prepare levoglucosenone using sulfated zirconia.

Sulfated zirconia was employed as catalyst for fast pyrolysis of cellulose to prepare levoglucosenone (LGO), a very important anhydrosugar for organic synthesis. The yield and the selectivity of LGO were studied in a fixed-bed reactor at different temperatures and cellulose/catalyst mass ratios. The experiments of catalyst recycling were also carried out. The results displayed that from 290 to 400 °C, the liquid and solid accounted for more than 95 wt % of products, and the higher temperature led to more liquid and less solid products. The introduction of SO₄²⁻/ZrO₂ could promote cellulose conversion and LGO production. The temperature had a similar effect on the yield and selectivity of LGO at different cellulose/catalyst mass ratios. The maximum yield was obtained at 335 °C. Although the structure of the parent ZrO₂ was retained after recycles, which was confirmed by X-ray diffraction and N₂ adsorption-desorption measurements, the activity of SO₄²⁻/ZrO₂ could only be partially recovered by simply calcination. The catalytic activity decrease could be mainly attributed to SO₄²⁻ leaching, and the activity could be restored by further impregnation of H₂SO₄.