Nanostructured Photocatalysts for Conversion of Lignocellulosic Waste to High-Value Chemicals

Green chemical production from lignocellulosic waste is widely considered attempted to produce the desired products economically and substituting fossil fuels. Especially, lignin, low-value waste of lignocellulosic biomass which is abundant aromatic structure components and can be also useful for high-value chemical production. In this work, the conversion of lignin to high-value chemicals was investigated by photocatalysis. TiO2 has been successfully exposed as a famous photocatalyst under UV light stimulation. Nevertheless, the limitation of the TiO2 photocatalytic system is the suitable light energy to activate electrons. Therefore, the utilization of lignin as carbonaceous materials to modify TiO2 composited photocatalysts (TiO2/lignin) to enhance the photocatalytic activity is our attempt. The carbon composite photocatalysts were synthesized by the sol-gel microwave technique. The effect of lignin loadings showed good characteristic properties for improvement of the performance of TiO2, including small crystallite size (7 nm of TiO2/lignin 1:0.5, compared with pristine TiO2-air 24 nm and TiO2-N2 9 nm) which are corresponding of grain size in TEM results, raise the photoabsorption in the visible and UV region, and decrease PL intensity which is significant of the lower rate of recombination. TiO2/lignin 1:0.5 shows the highest surface area (92.89 m2/g, compared with pristine TiO2-air 6.15 m2/g and TiO2-N2 46.74 m2/g) and shows the best photocatalyst with enhanced photocatalytic activity by increasing lignin conversion up to 40.28% under UVA irradiation and 15.73% under visible light. Finally, High-value chemicals, such as vanillin, were found after photocatalysis.