Efficient acrolein production through selective dehydration of biomass-derivable glycerol was investigated over the vanadium pyrophosphate oxide (VPO) catalysts. Employing polyethylene glycol (PEG) additive in the preparation media and activating the VPO precursors in the butane-air atmosphere considerably enhanced catalyst performance for the target reaction. An acrolein yield of 70.1mol% can be achieved over the as-synthesized VPO catalyst using an aqueous glycerol solution (36.5wt.%) feed and a liquid hourly space velocity (LHSV) of 4h-1 at 320°C. Moreover, the derived VPO catalyst can handle heavy loading of reaction feed, such as a concentrated glycerol solution (50.0wt%) or a notably high LHSV of 12h-1, and still retain reasonable acrolein yields (45-65mol%), giving acrolein formation rate up to 35.3mmolgcat-1h-1. Techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and hydrogen temperature programmed reduction (H2-TPR) were employed to explore the nature of catalysts. Type of alcohol and addition of PEG adopted in catalyst preparation showed significant impact on sample crystallinity/morphology, surface V5+/V4+ ratio, VO bonding strength, and Brønsted surface acidity. Balanced surface V5+/V4+ ratio and suitable density of medium strong acid sites are found to be critical to accomplish superior activity.
Scopus Subject Areas
- Environmental Science(all)
- Process Chemistry and Technology
- Preparation chemistry
- Vanadium pyrophosphate oxide