Ordered WO_x/mesoporous SnO₂ catalysts with excellent acetalization performance for producing bio-additives from glycerol

Highly ordered WO_x/mesoporous SnO₂ (WO_x/meso‑SnO₂) catalysts with varying WO_x loadings of (5 ∼ 20) wt% displaying excellent catalytic performance were demonstrated in the acetalization of glycerol with acetone. The synthesized catalysts were analyzed using various techniques including X-ray diffraction, N₂-isotherm, electron microscopy, H₂ temperature programmed reduction, raman spectroscopy, and thermogravimetric analysis. For the acetalization of glycerol with acetone, the most active catalyst was found to be WO_x/meso‑SnO₂ with 20 wt% WO_x, and the maximum conversion of glycerol (100%) was obtained after 2 h at 20 °C, providing 97.4% selectivity (97.4% yield) for the five-membered product (solketal), due to the presence of a large number of acidic sites on the surface of the catalyst. The catalytic activity of 20 wt% WO_x/meso‑SnO₂ was also studied in a flow reactor. Tests were carried out at 30 °C, acetone/glycerol=30, WHSV=(4 or 8) h ^{− 1}, and atmospheric pressure for 24 h. The catalytic results showed that, when the WHSV was 4 h ^{− 1}, after 24 h of time-on-stream, both the glycerol conversion of (100 to 97.9)% and solketal yield of (97.5 to 93.6)% slightly decreased. This result suggests the potential of the 20 wt% WO_x/meso‑SnO₂ catalyst for the industrial acetalization of glycerol.