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2D-to-3D transformation of layered zeolite precursors (e.g., MCM-22P, IPC-1P, pre-FER) into three-dimensional frameworks in combination with metal encapsulation has been recently shown as efficient synthetic strategy to stabilize metal clusters in a zeolite matrix. Even though, tailoring the number of acid sites in a zeolite support and its effect on the properties of thus prepared metal@zeolite materials (e.g., metal dispersion and catalytic activity) remained unrevealed. Herein, we report on the synthesis of Pd@MCM-22 catalysts via modified 2D-to-3D transformation method, which allows to achieve close to nominal loading of noble metal (e.g., 0.1, 0.3, 0.8 wt.%) by time-separation of swelling of MCM-22P layered zeolite precursor and subsequent incorporation with metal. In turn, alternating Si/Al ratio of MCM-22P (e.g., Si/Al = 15, 20, 30) enabled the preparation of Pd@MCM-22 catalysts with variable concentration of acid sites (0.28 – 0.55 mmol/g), while not affecting the Pd dispersion. Decrease in Pd dispersion with increasing metal loading was accompanied with declining catalytic activity in a model reaction of selective hydrogenation of nitro-group in 3-nitrotoluene: 0.1 wt. % Pd (dispersion = 52.6%, reaction rate = 21.2 mol·g-1Pd·h-1) > 0.3 wt. % Pd (9.6 mol·g-1Pd·h-1) > 0.8 wt. % Pd (23.2%, 3.7 mol·g-1Pd·h-1). The results of this study reveal that the reported synthesis strategy can be successfully used to confine small metal nanoparticles in a zeolite matrix while tuning its acidic characteristics for designing bifunctional metal-acidic catalysts.

International audience; A set of supported Co3O4 catalysts have been designed and prepared to study the effect of textural characteristics and Brønsted acid sites concentration of MWW zeolite support, as well as cobalt loading on catalyst activity. Detailed characterization of the catalysts with a thorough study on their performance in the total oxidation of toluene and propane revealed that MCM-22 is the optimal support and that increasing Si/Al and decreasing external surface of MCM-22 positively affect the activity of supported Co3O4 catalysts, which is determined by their low-temperature reducibility. The activity of the Co/MCM-22 catalysts increased with cobalt content (5-20 wt %), consistent with enhancing the amount of low-temperature reducible Co3O4. The optimized catalyst containing 20% Co supported on dealuminated MCM-22 presented high turnover frequency (TOF) values in both toluene (2.6 × 10-5 s-1 at 270 °C) and propane (3.9 × 10-5 s-1 at 215 °C) oxidation and was characterized by outstanding cycling stability, long-term durability, water tolerance, and sintering resistance.

A set of supported Co