<p>Inexpensive and active catalysts can improve the technical and economic efficiency of waste textiles. Therefore, several inexpensive metal materials have been added to clay-like montmorillonite (MMT) to improve its catalytic activity in the pyrolysis of polyester/viscose fibres. The Brunauer‒Emmett‒Teller (BET) method indicated that the MMT had a high specific surface area, which provided sufficient internal space for active metal dispersion and ample adsorption capacity for tar distillate and cracking products. Temperature-programmed desorption of NH₃ (NH₃-TPD) revealed that the acidity balance of the catalyst improved after different metals were added. Pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) studies revealed that the selectivity of MMT for aromatics increased after metal loading, and the selectivities of the Zn-containing MMT for monocyclic aromatics (MAHs) and polycyclic aromatics (PAHs) were the highest, at 46.70% and 27.68%, respectively. MMT-supported Ni increased the content of heavy aromatic hydrocarbons formed, with PAH contents of up to 43.16%, which made the catalyst more prone to deactivation during catalytic pyrolysis. The Mg-containing MMT showed similar catalytic activity to that of Ca-containing MMT in the catalysis of fibre pyrolysis; both produced more aromatics and favoured the formation of PAHs. These results indicate that various metal-containing MMT catalysts had significant effects on the yields of aromatic hydrocarbons during pyrolysis.</p>