[EN] The crystallization of Al-rich CHA zeolites with an ultra-low organic structure directing agent (OSDA) content and without using pre-crystallized FAU zeolites as Si and/or Al sources has been accomplished by controlling the nucleation step. Indeed, the use of ¿gel-type¿ seeds containing discrete nanosized CHA nanoparticles (i.e. below 100 nm) combined with the understanding of the seed-assisted crystallization mechanism has allowed the efficient preparation of Al-rich CHA materials using ultra-low methyltriethylammonium (MTEA) contents (MTEA/Si molar ratios ~ 0.03¿0.04), making this synthetic route very cost-competitive compared to recent synthesis improvements for CHA using substoichiometric contents of expensive OSDAs (i.e. N,N,N-trimethyladamantammonium, TMAda). The optimized Al-rich CHA materials, after incorporating the catalytically active copper cations, perform as ideal catalysts for the selective catalytic reduction (SCR) of NOx with ammonia relevant for heavy-duty applications.

The authors acknowledge financial support by Umicore, Spanish Government through PID2021-122755OB-I00 funded by MCIN/AEI/10.13039/501100011033 and TED2021-130739B-I00 funded by MCIN/AEI/10.13039/501100011033/EU/PRTR, and by Generalitat Valenciana through AICO/2021/201. The authors are also thankful for the Severo Ochoa financial support by the Spanish Ministry of Science and Innovation (CEX2021-001230-S/funding by MCIN/AEI/10.13039/501100011033). E.B.-J. acknowledges the Spanish Government for a FPI scholarship (PRE2019-088360). The Electron Microscopy Service of the UPV is also acknowledged for their help in sample characterization