The development of efficient catalysts for the chemical recycling of poly(ethylene terephthalate) (PET) is essential to tackling the global issue of plastic waste. There has been intense interest in heterogeneous catalysts as a sustainable catalyst system for PET depolymerization, having the advantage of easy separation and reuse after the reaction. In this work, we explore heterogeneous catalyst design by comparing metal-ion (Fe3+) and metal-oxide nanoparticle (Fe2O3 NP) catalysts immobilized on mesoporous silica (SiO2) functionalized with different N-containing amine ligands. Quantitative solid-state nuclear magnetic resonance (NMR) spectroscopy confirms successful grafting and elucidates the bonding mode of the organic ligands on the SiO2 surface. The surface amine ligands act as organocatalysts, enhancing the catalytic activity of the active metal species. The Fe2O3 NP catalysts in the presence of organic ligands outperform bare Fe2O3 NPs, Fe3+-ion-immobilized catalysts and homogeneous FeCl3 salts, with equivalent Fe loading. X-ray photoelectron spectroscopy analysis indicates charge transfer between the amine ligands and Fe2O3 NPs and the electron-donating ability of the N groups and hydrogen bonding may also play a role in the higher performance of the amine-ligand-assisted Fe2O3 NP catalysts. Density functional theory (DFT) calculations also reveal that the reactivity of the ion-immobilized catalysts is strongly correlated to the ligand-metal binding energy and that the products in the glycolysis reaction catalyzed by the NP catalysts are stabilized, showing a significant exergonic character compared to single ion-immobilized Fe3+ ions.

[EN] Interzeolite Transformation Intermediates (ITIs) produced by the partial interconversion of FAU to BEA zeolites were systematically investigated as catalysts for the cracking of low-density polyethylene (LDPE) and polystyrene (PS). These materials exhibit a unique combination of structural features, including strong Br & Oslash;nsted acidity and well-developed intracrystalline mesoporosity. Comprehensive characterization by XRD, N2 physisorption, UV-Vis Raman spectroscopy, 27Al MAS NMR, and TEM confirmed their hybrid nature, incorporating elements of both the parent FAU and daughter BEA zeolites. Catalytic performance was benchmarked against fully formed zeolites (FAU, BEA) and a mesoporous aluminosilicate (Al-MCM-41). For LDPE cracking, strong acidity and well-defined microporosity were found to be critical, with conventional zeolites outperforming ITIs. In contrast, ITIs exhibited superior catalytic activity and stability for PS cracking owing to their well-connected mesoporosity and balanced acidity profiles. A key finding of this study is that a catalyst with both large mesoporosity and the strongest acidity is not always the best. For example, PS cracking benefited from catalysts with moderate acidity and high mesoporosity, while LDPE cracking required materials with stronger acid sites. In all cases, ITIs outperformed mesoporous catalysts derived from amorphous precursors, with Al-MCM-41 consistently showing the lowest catalytic activity. Operando FT-IR-GC-MS provided insights into the reaction mechanisms and product distributions, revealing the role of ITIs in enhancing resistance to coking deactivation. ITIs were advantageous for PS dealkylation and for promoting the selective formation of olefins during LDPE cracking. Temperatureprogrammed oxidation (TPO) studies showed that the well-interconnected mesoporosity of ITIs facilitated coke oxidation compared to the poorly interconnected channels of conventional zeolites. These results highlight the potential of ITIs as tailor-made catalysts for plastic waste valorization, with performance tunable by their intermediate structural properties., This project has received funding from the European Union's Horizon 2020 Research and Innovation program under Grant agreement No 872102, the Spanish Ministry of Science, Grant PID2021-1287610B-C21 by MCIN/AEI/10.13039/501100011033 by "ERDF A way of mak-ing Europe", the Generalitat Valenciana through CIPROM/2023/2, and the Advanced Materials programme, supported by MCIN with funding from European Union NextGenerationEU (PRTR-C17.I1) and by Generalitat Valenciana. J.M-O acknowledges the financial support from the European Union - NextGeneration EU through the Universitat Polcitecnica de Valencia, Ministerio de Universidades, Plan de Recuperacion, Transformacion y Resiliencia for the Margarita Salas grant. This project has received funding from the European Union's Horizon 2020 research and innovation programme under Grant Agreement No 101008500. KGM, KAT, and OR thank the National Science Centre, Poland [Grant No. 2021/43/B/ST4/00307] . The research was partially carried out using research infrastructure purchased with the funds of the European Union in the framework of the Smart Growth Operational Programme, Measure 4.2; Grant No. POIR.04.02.00-00-D001/20-00, "ATOMIN 2.0 - ATOMic scale science for the INnovative economy".

[EN] Determining the distribution of aluminium in zeolite frameworks remains a significant challenge, due to the limited sensitivity of conventional characterization techniques. To overcome this issue, we have developed a procedure which combines experimental two-dimensional (2D) solid-state NMR spectroscopy with machine learning (ML) techniques. To validate the approach, we have applied it to achieve a detailed assignment of Al environments in zeolite RTH. A reactive ML potential was used to model long-timescale framework dynamics under realistic conditions, including temperature and hydration, alongside the accurate prediction of isotropic NMR chemical shifts. Comparison between theoretical and experimental spectra reveals that Al preferentially occupies the T2 sites, with under-population of the other T-sites. The excellent agreement between computed and observed NMR data demonstrates that this ML-augmented spectroscopic approach is a powerful tool for quantitative elucidation of Al distributions in structurally complex zeolites, going far beyond the limitations of traditional quantum chemical approaches., Charles University Centre of Advanced Materials (CUCAM) (OP VVV Excellent Research Teams, project number CZ.02.1.01/0.0/0.0/15003/0000417) is acknowledged. This work was supported by the Ministry of Education, Youth and Sports of the Czech Republic through the e-INFRA CZ (ID: 90254). CJH acknowledges support via the ERC_CZ project LL 2104. CJH, AE, DBA and LG acknowledge the Czech Science Foundation (CJH: GA & Ccaron;R standard project 23-07616S). CB acknowledges the funding from the European Union's Horizon Europe research and innovation program under the ERA-PF grant agreement no. 101180584. This work was supported by MICIU/AEI/10.13039/501100011033 (projects CEX2021-001230-S), co-funded by the ERDF/EU (PID2022-136934OB-I00) and by the European Union NextGeneration EU/PRTR (TED2021-130191B-C41). Grant CIPROM/2024/050 funded by Generalitat Valenciana is acknowledged. PANACEA project funded by the European Union's Horizon 2020 research and innovation program under grant agreement no. 101008500 is acknowledged.