## 1 Introduction
These catalysts efficiently reduce the temperature needed for breaking and transform the product yield and composition [11]. Although commercial catalysts display stability and easy recyclability, their high cost is one of the main limitations for large-scale plastic waste recycling. A potential solution to this limitation can be replacing them with low-cost materials without supply problems. In this sense, local clay and clay-based materials are good candidates as low-cost catalysts for plastic waste pyrolysis [19]. In the case of PPE waste, some previous studies have reported the valorization by pyrolysis of different types of PPE, including PPE components [20; 21], complete PPE [22; 23], combinations of different PPE, such as face masks and gloves [24], or co-pyrolysis of PPE and other type of waste, such as food waste [25]. Some studies have performed experiments in thermobalance and have obtained kinetic parameters for different masks [26; 27; 28]. Other authors have also conducted computer simulations for the thermal conversion of face masks by pyrolysis [27]. Furthermore, [PERSON] et al. [29] examined the conversion of surgical masks into useful products using metal oxides (CeO\({}_{2}\) and Nb\({}_{2}\)O\({}_{5}\)) as catalysts. These authors constructed a detailed kinetic model that can be useful to industrial pyrolysis reaction units for the recycling of the face mask waste. [PERSON] et al. [30] have also analyzed the catalytic pyrolysis of face masks by using zeolite catalysts to produce benzene, toluene, ethylbenzene, and xylene (BTEX) compounds. Other researchers have oriented their investigation to the development of porous carbon materials from face masks for energy storage applications (lithium sulfur batteries [31] or supercapacitors [32]). More recently, [PERSON] et al. [13] have analyzed the applicability of the hydroprolysis and hydrocracking processes to convert face masks into fuel-range iso-alkanes using Ru/C as a catalyst. [PERSON] et al. [33] examined the thermal pyrolysis of different medical waste including face masks, gloves, and other PPE waste with a special emphasis on the characteristics of the obtained liquid product. The authors concluded that the fuel properties of the liquid product from pyrolysis of face masks, gloves, and other PPE waste were closer to diesel fuel. However, to the best of our knowledge, clay and clay-based materials were not studied in catalytic pyrolysis of any PPE waste. Therefore, in this study, the thermal and catalytic pyrolysis over an abundant Spanish clay of surgical masks and FFP2 masks was investigated in-depth. Sepiolite clay was chosen because, although it does not contain active components (it is a fibrous hydrated magnesium silicate), it has received considerable attention in catalysis as a support as well as a catalyst [34]. In addition, it is characterized by a highly specific surface area, and water and other inorganic and organic molecules can be accommodated in the sepiolite structure and react between them [35; 36; 37; 38]. Some of the main advantages of using sepiolite as a catalyst are its natural origin, low cost (price between 32 and 1000 USD/t in the function of application and processing), and high availability in Spain (Spain is one of the main world producers of sepiolite) [39]. First, the influence of pyrolysis temperature and the interaction of sepiolite on the yields and composition of pyrolysis products (biochar, biooil, and syngas) were studied in a typical pyrolysis temperature range (450-550 \({}^{\circ}\)C). Then, the regeneration of the sepiolite was evaluated in three consecutive pyrolysis cycles. The results will support the applicability of this new route of management for PPE that aims to mitigate plastic contamination caused by inadequate management and to achieve sustainable upcycling of waste to high value-added by-products in the future.