Synthesis of binderless FAU-X (13X) monoliths with hierarchical porosity

Youcef Didi (1) , Bilel Said (1) , Thomas Cacciaguerra (1) , Khac Long Nguyen (2) , Véronique Wernert (2) , Renaud Denoyel (2) , Didier Cot (3) , Wassim Sebai (1, 3) , M-P. Belleville (3) , José Sanchez-Marcano (3) , François Fajula (1) , Anne Galarneau (1)

1 ICGM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
2 MADIREL - Matériaux divisés, interfaces, réactivité, électrochimie
3 IEM - Institut Européen des membranes

elf-standing binderless FAU-X monoliths with hierarchical trimodal porosity have been synthesized for the first time by a double pseudomorphic transformation. Parent silica monoliths obtained by the combination of spinodal decomposition and sol-gel process have first been synthesized. The silica monoliths have been then transformed into silica-alumina monoliths (0.25 < Al/Si < 0.40) in low NaOH concentration ([NaOH] = 0.24 mol/L) at 40 °C for 24 h. Silica-alumina monoliths have been then transformed into FAU-X monoliths featuring nanocrystals in the struts at high NaOH concentration ([NaOH] = 2.2 mol/L) with an aging step at 40 °C for 4 days and a crystallization step at 100 °C for 24 h. The FAU-X monoliths feature macropores with diameters adjustable from 3 to 20 μm (similar to the parent silica monolith). The skeleton of the FAU-X monoliths is formed by an aggregation of two populations of FAU-X nanocrystals (100–200 nm/400–500 nm) generating a secondary porosity between the nanocrystals of 30–1000 nm in diameter, centered at 300 nm. The FAU-X monoliths present three levels of porosity with a macropore volume of ca. 1.0 mL/g, a secondary pore volume of ca. 0.40 mL/g and a micropore volume of 0.30 mL/g. These new FAU-X monoliths with hierarchical porous structure fulfill the requirements of high performance adsorbents for continuous flow process intensification.

Mots clés: 13X monolith; Binderless zeolite; Pseudomorphic transformation; Zeolite nanocrystal; Silica-alumina monolith; Spinodal decomposition

Domaines: Matériaux

Youcef Didi, Bilel Said, Thomas Cacciaguerra, Khac Long Nguyen, Véronique Wernert, et al.. Synthesis of binderless FAU-X (13X) monoliths with hierarchical porosity. Microporous and Mesoporous Materials, 2019, 281, pp.57-65. ⟨10.1016/j.micromeso.2019.03.003⟩. ⟨hal-02064129⟩