Catalysis 2023 Issue

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Figure 3 Dispersion of various metal-containing zeolites prepared using Zeopore’s process (green). The impregnation (IWI) of a conventional zeolite with Mg is included in orange as reference on the left. On the right, impregnation (IWI) of Pt is executed on a parent zeolite (orange), a metal-free mesoporous zeolite (blue), and a Mg-containing mesoporous material (green)

This bespoke metal meso- porisation does not apply to noble metals such as Pt and Pd. Yet, it does imply potential ben- efits when using noble metals. For example, metal promoters/ enhancers used in combination with noble metals, such as Mg, can be introduced in a superior fashion, in turn enabling supe - rior dispersions of the noble metal and improved hydroge - nation potential. Metal dispersions are mostly

Figure 4 Electron microscopy pictures showing large NiO clusters (white) on conventional MFI crystals following traditional incipient wetness impregnation (left), and hard-to- observe Ni species finely spread over a mesoporous MFI crystal (middle, right). Ni is shown in red as identified using elemental mapping (right). The scale bar applies to all images

relevant when combined with sufficient stability. The anchor - ing of the metal particles obtained by metal mesoporisation technology was therefore assessed on powder level by exposing the material to subsequent post-synthetic steps such as ion exchange. Zeopore’s derived material proved that the ion exchange did not remove any significant amount of metals. In contrast, when applied after a standard metal impregnation, over 99% of the metal is removed. Compromise-free introduction of a secondary metal function The surprising resistance to further post-synthetic treat - ment enables another positive feature of the proprietary materials being discussed: their acidity. The technol - ogy enables the depositing of large amounts of metals on zeolite powders while preserving the intrinsic zeolitic Bronsted acidity. Accordingly, whereas traditionally a trade-off between Bronsted and Lewis acidity is obtained (see Figure 5 ). 3 Zeopore enables unique acidity profiles. This approach is only able to combine the selectivity ben- efits of metals with preservation or enhancement of the intrinsic catalytic activity. Tunable inside and outside In addition to the unique metal/Bronsted acidity combi - nations, the metal anchoring on the outside facilitates

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Lewis acidity , % Metal-based selectivity descriptor

Figure 5 The preservation of Bronsted acidity during the introduction of the metal function (green) enables unique combinations of Bronsted and Lewis acidities. Orange highlights acidity development following standard metal impregnation3

Catalysis 2023