Catalytic conversion of lignin to bio-oil over PTA/MCM-41 catalyst assisted by ultrasound acoustic cavitation

The ultrasound-assisted depolymerization of lignin was successfully conducted over a synthesized PTA/MCM-41 catalyst under different reaction conditions. Firstly, the structure of the prepared PTA/MCM-41 catalyst was characterized by various techniques, and its acidity was determined using Fourier-transform infrared spectroscopy (FT-IR) of pyridine adsorption and temperature-programmed desorption of ammonia (NH3-TPD). Then, the effects of ultrasound frequency, reaction temperature, and reaction time on the distribution and yield of the products of the ultrasound-assisted depolymerization of lignin were studied. The optimum reaction conditions were obtained at an ultrasound frequency of 30%, a reaction temperature of 300 degrees C, and a reaction time of 6 h. Under the optimum reaction conditions, the conversion of lignin depolymerization was equal to 94.79%, and the yield of phenolic monomers (PM) and lignin bio-oil was 8.37% and 90.58% respectively.