کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
46736 | 46446 | 2011 | 11 صفحه PDF | دانلود رایگان |
The gas-phase dehydration of glycerol was conducted over silica–alumina catalysts with different Si/Al molar ratios. For comparison, SiO2 and η-Al2O3 were also examined. A variety of techniques, X-ray diffraction (XRD), temperature-programmed desorption of ammonia (NH3-TPD), temperature-programmed oxidation (TPO) with mass spectroscopy (MS), infrared spectroscopy (FT-IR) after the adsorption of pyridine or glycerol, solid-state 29Si and 27Al magic-angle spinning nuclear magnetic resonance (MAS/NMR) spectroscopy, Raman spectroscopy, and CHNS analysis, were employed to characterize the catalysts. The initial glycerol conversion at 315 °C was strongly dependent on the total amount of acid sites over the silica–aluminas. The acrolein yield was proportional to the concentration of the Brønsted acid sites, whereas the 1-hydroxyacetone yield was proportional to the concentration of the Lewis acid sites. Among the tested catalysts, Si0.8Al0.2Ox showed the highest acrolein selectivity during the initial 2 h of the reaction. As long as the molar ratio between water and glycerol was in the range 2–11, the acrolein selectivity increased significantly with the water content of the feed.
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► Gas-phase dehydration of glycerol was examined over silica–alumina catalysts.
► The glycerol conversion depends on the total amount of acid sites.
► The acrolein yield increases with the concentration of the Brønsted acid sites.
► The 1-hydroxyacetone yield increases with the concentration of the Lewis acid sites.
► The acrolein selectivity increases with the water content of the feed.
Journal: Applied Catalysis B: Environmental - Volume 107, Issues 1–2, 31 August 2011, Pages 177–187