Synthesis of levulinic acid from tobacco stalk via steam explosion and oxidation–hydrolysis route

BACKGROUND

Tobacco stalk, the main waste from tobacco planting, was used as raw material to produce levulinic acid, one of the most important platform chemicals. It was reported that steam explosion was an efficient method to treat lignocellulose to hydrolyze the hemicellulose component. Oxidation treatment combined with catalysis of Al₂(SO₄)₃ proved to be efficient for the conversion of cellulose to levulinic acid in our recent report. Here, tobacco stalk was first treated by steam explosion, and then the solid residue was oxidized and converted to levulinic acid in the presence of Al₂(SO₄)₃.

RESULTS

A xylo-oligosaccharide yield of 6.6 g 100 g⁻¹ was obtained from tobacco stalk via steam explosion. 15.4 g 100 g⁻¹ (39.6 mol%) yield of levulinic acid was obtained from oxidized tobacco stalk in water at 180 °C in 5 h using Al₂(SO₄)₃ as a catalyst. As high as 20.8 g 100 g⁻¹ (53.5 mol%) yield of levulinic acid can be obtained using NaCl as a co-catalyst.

CONCLUSION

Steam explosion was efficient for the depolymerization of the hemicellulose component of tobacco stalk to xylo-oligosaccharide. A simple salt of Al₂(SO₄)₃ showed good catalytic activity for conversion of oxidized tobacco stalk to levulinic acid. Nicotine in tobacco stalk promoted the formation of lactic acid. Thus, the yield of levulinic acid decreased in the presence of nicotine. NaCl enhanced the catalytic performance of Al₂(SO₄)₃. © 2024 Society of Chemical Industry (SCI).