Production of green phenol by microwave-assisted catalytic pyrolysis of epoxy-based carbon fiber reinforced plastic from wind turbine blades

Abstract

Recycling the waste wind turbine blades (WWTBs) is one of the key issues for the sustainable development of wind energy. Microwave-assisted catalytic pyrolysis offers the potential to obtain valuable products from the WWTBs. In this study, epoxy-based carbon fiber reinforced plastic (CFRP) from wind turbine blades was performed to microwave-assisted catalytic pyrolysis for phenol production. Four zeolite catalysts (ZSM-5, β30, MOR, and MCM-41) were characterized and used for pyrolysis. The solid, liquid, and gaseous products were collected respectively. The compositions of the condensed tar and non-condensed gas were carefully analyzed by GC-MS and GC, respectively. The performance of the catalysts was compared and the effects of microwave power and reactor temperature on the product characteristics were discussed. The results indicate that the conversion of the phenol precursors, including diphenol A, 4-isopropenyl phenol, 4-isopropyl phenol, and 4-allylphenol, to phenol is promoted by the catalysts. β30 shows the best performance for phenol production among the catalysts, benefiting from its high specific surface area and acidity. Increasing the microwave power from 500 W to 800 W favors the initial pyrolysis of epoxy resin, thus improving the phenol yield. 600 W is preferred due to excessively increasing microwave power has a limited effect on promoting phenol generation and has the potential to damage the carbon fibers. Increasing the temperature from 350 °C to 650 °C promotes the cracking of resin and intermediate products. Pyrolysis at 450 °C is preferred due to the highest phenol yield. With the suggested condition (β30, 600 W, and 450 °C), the phenol yield is ∼36.28 % in the tar. The findings of this study provide fundamental information and guidance for the industrial application of directed synthesis of phenol from WWTBs.