TITLE: Direct hydrothermal synthesis of zeolites and beyond: Interchain expansion and topotactic condensation
AUTHOR: Huajian Yu- Nanostructured Hybrid, Biohybrid and Porous Materials Group (read here an interview with him)
SUPERVISED BY: Miguel Camblor and Zihao Rei Gao, ICMM-CSIC
WHEN: October 10 - 11AM
WHERE: Salón de Grados, Escuela Politécnica Superior UAM
ABSTRACT:
This PhD thesis explores innovative strategies for synthesizing novel zeolite structures, which are microporous crystalline materials widely used in catalysis, ion exchange, and adsorption due to their exceptional stability and porosity. The research employs three main approaches: conventional hydrothermal synthesis, topotactic condensation, and interchain expansion. Through hydrothermal synthesis, the author investigates various parameters—such as organic structure-directing agents (OSDAs), composition, framework atoms, and crystallization conditions—leading to the discovery of five new materials: zeolites HPM-9 and HPM-18, and layered zeolite precursors HPM-3, HPM-22, and HPM-23. These precursors undergo topotactic transformations into JSN, MTF, and HEU zeolites. The thesis also introduces a novel interchain expansion method by sililation of the complex chain silicate ZEO-2, resulting in the synthesis of interrupted zeolites ZEO-4A and ZEO-4B, which topotactically condense into ZEO-5—a fully connected 3D zeolite with extra-large pores and record-low framework density (1.10g/cc). After introduction of Ti, Ti-ZEO-5 demonstrates promising catalytic performance in oxidation reactions involving large molecules. The work investigates structure direction, propose the possibility of extensive violations of the Loewestein rule through topotactic condensation of layered aluminosilicates and demonstrate the new interchain expansion synthesis reaction.
