Size control of self-supported LTA zeolite nanoparticles monoliths

• Zeolite A monoliths with trimodal porosity (micro-/meso-/macropore) were synthesized.
• Pseudomorphic synthesis from silica monolith (6 mm × 5 cm) was used for shape control.
• Nanozeolites were successfully obtained by control of aging and crystallization steps.
• Aggregation of hierarchical zeolite with homogeneous mesoporosity were realized.
• Similar homogeneous mesoporosity was obtained with organosilane templated zeolites.

LTA zeolites are used in many applications as diverse as chemistry, physics, medicine, agriculture. By exploiting the concept of pseudomorphic transformation, i.e. using silica monoliths featuring macro- and mesopores as silica source, we manage to shape LTA zeolites as centimetric monoliths (6 mm diameter, 5 cm length) with trimodal hierarchical porosity (micro-, meso- and macropores). The skeleton of the monolith is formed by an aggregation of LTA nanocrystals of ca. 100 nm leading to mesopores due to voids between the nanocrystals. Diverse LTA nanocrystal shapes and sizes were realized by controlling aging time and crystallization temperature. These unique self-standing monoliths of LTA nanozeolites feature flow-trough macropores of 3–4 microns highly suitable for high mass transport of liquids, homogeneous distributions of mesopores for high diffusion of molecules and ions and therefore a high accessibility to zeolites active sites. Together with an easy handling, these materials offer the possibility to intensify many processes using classical LTA zeolite crystals.

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