Zeolite Synthesis in the Presence of Metallosiloxanes for the Quantitative Encapsulation of Metal Species for the Selective Catalytic Reduction (SCR) of NOx

• Published in: Angewandte Chemie International Edition 2023-10, Vol.62 (40), p.e202311048-n/a
• Main Authors: Khairova, Rushana, Komaty, Sarah, Dikhtiarenko, Alla, Cerrillo, Jose Luis, Veeranmaril, Sudheesh Kumar, Telalović, Selvedin, Tapia, Antonio Aguilar, Hazemann, Jean‐Louis, Ruiz‐Martinez, Javier, Gascon, Jorge
• Format: Article
• Language: English
• Subjects: Ammonia; Catalytic activity; Chemical reduction; Clustering; Dispersion; Encapsulation; H2O/SO2 Tolerance; Heavy metals; Iron; Metals; Selective catalytic reduction; Selective Catalytic Reduction (SCR); Siloxanes; Single-Site Catalyst; Sulfur dioxide; Synthesis; Transition metals; Zeolite; Zeolites
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202311048

Metal encapsulation in zeolitic materials through one‐pot hydrothermal synthesis (HTS) is an attractive technique to prepare zeolites with a high metal dispersion. Due to its simplicity and the excellent catalytic performance observed for several catalytic systems, this method has gained a great deal of attention over the last few years. While most studies apply synthetic methods involving different organic ligands to stabilize the metal under synthesis conditions, here we report the use of metallosiloxanes as an alternative metal precursor. Metallosiloxanes can be synthesized from simple and cost‐affordable chemicals and, when used in combination with zeolite building blocks under standard synthesis conditions, lead to quantitative metal loading and high dispersion. Thanks to the structural analogy of siloxane with TEOS, the synthesis gel stabilizes by forming siloxane bridges that prevent metal precipitation and clustering. When focusing on Fe‐encapsulation, we demonstrate that Fe‐MFI zeolites obtained by this method exhibit high catalytic activity in the NH3‐mediated selective catalytic reduction (SCR) of NOx along with a good H2O/SO2 tolerance. This synthetic approach opens a new synthetic route for the encapsulation of transition metals within zeolite structures. A one‐pot hydrothermal zeolite synthesis using metallosiloxane precursors enables a quantitative encapsulation of metal species into the zeolite. For Fe‐MFI zeolite the approach facilities a homogeneous distribution of the Fe species throughout the zeolite framework and leading to improved catalytic activity with good tolerance to H2O/SO2 in the NH3‐selective catalytic reduction (SCR) of NOx across a wide temperature range.