A substantial quantity of discarded tires has inflicted harm on the environment. Microwave pyrolysis of discarded tires emerges as an efficient and environmentally friendly method for their recycling. This research innovatively utilizes the characteristics of microwave rapid and selective heating to pyrolyze waste tires into porous graphene under the catalysis of KOH etching. Moreover, this study comprehensively investigates the dielectric characteristics and heating behavior of waste tires and different proportions of waste tire–KOH mixtures. It validates the preparation of graphene through KOH-catalyzed microwave pyrolysis of waste tires, tracking morphological and structural changes under varying temperature conditions. The results indicate that optimal dielectric performance of the material is achieved at an apparent density of 0.68 g/cm3 at room temperature. As the temperature increases, the dielectric constant gradually rises, particularly reaching a notable increase around 700 °C, and then stabilizes around 750 °C. Additionally, the study investigates the penetration depth and reflection loss of mixtures with different proportions, revealing the waste tire–KOH mass ratio of 1:2 demonstrates favorable dielectric properties. This research highlights the impressive microwave responsiveness of the waste tire–KOH mixture, Upon the addition of KOH, the mixed material exhibits an augmented dielectric constant and relative dielectric constant, supporting the viability of KOH-catalyzed microwave pyrolysis for producing porous graphene from waste tires. This method is expected to provide a new method for the valuable reuse of waste tires and a technology for large-scale, efficient and environmentally friendly production of graphene.

KOH etching catalyzed microwave pyrolysis of waste tires to prepare porous graphene
    Abstract
    1 Introduction
    2 Materials and methods
        2.1 Materials
        2.2 Dielectric properties measurement system and measurement mechanism
        2.3 Method of detecting dielectric properties
        2.4 Microwave heat treatment equipment and sample analysis
        2.5 Other characterizations
    3 Results and discussion
        3.1 Effect of apparent density on dielectric properties
        3.2 The effect of temperature on the dielectric properties of materials
        3.3 Reflection loss analysis
        3.4 Microwave heating behavior
        3.5 Microwave pyrolysis process exploration and product characterization
            3.5.1 Microwave pyrolysis process
            3.5.2 Characterization of pyrolysis products
    4 Conclusion
    Acknowledgements 
    References

• Wang Chen(Faculty of Metallurgy and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, Yunnan, China)
• Bingguo Liu(Faculty of Metallurgy and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, Yunnan, China, Key Laboratory of Unconventional Metallurgy, Ministry of Education, Kunming University of Science and Technology, Kunming 650093, Yunnan, China, National Key Laboratory of Clean Utilization of Complex Nonferrous Metals, Kunming University of Science and Technology Laboratory, Kunming 650093, Yunnan, China)
• Guolin Luo(Qujing Zhongyi Fine Chemical Co., Ltd., Qujing 655003, Yunnan, China)
• Chao Yuwen(Faculty of Metallurgy and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, Yunnan, China)
• Fang Peng(Qujing Zhongyi Fine Chemical Co., Ltd., Qujing 655003, Yunnan, China)
• Siyu Gong(Faculty of Metallurgy and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, Yunnan, China)
• Keren Hou(Faculty of Metallurgy and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, Yunnan, China)
• Yunfei An(Faculty of Metallurgy and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, Yunnan, China)
• Guangxiong Ji(Faculty of Metallurgy and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, Yunnan, China)
• Bangjian Wu(Faculty of Metallurgy and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, Yunnan, China)