Di- and trioxacyclohexane as structure directing molecules in the synthesis of zeolites omega and ECR-1

Corentin Chatelard (1) , Mathias Dodin (2) , Raquel Martinez-Franco (2) , Alain Tuel (1)

1 IRCELYON - Institut de recherches sur la catalyse et l'environnement de Lyon
2 IFPEN - IFP Energies nouvelles

Six-membered ring cyclohexane derivatives with 2 oxygen (1,4-dioxane or p-dioxane) and 3 oxygen (1,3,5-trioxane) atoms have been used as organic molecules in the synthesis of zeolites omega (MAZ framework type) and ECR-1 (EON framework type). Both molecules yield zeolite omega at moderate temperatures with a composition and aluminum distribution similar to those obtained with more standard organics such as the tetramethylammonium cation. If the preparation of zeolite omega with p-dioxane was previously known, the use of 1,3,5-trioxane had never been reported in the literature. The most interesting feature of 1,3,5-trioxane is that these molecules could be released from the structure at very low temperature, typically 300 °C below the temperature observed with p-dioxane. When the alkalinity of synthesis gels was decreased, zeolite omega was progressively replaced by ECR-1 in the presence of 1,3,5-trioxane but not in the presence of p-dioxane. The relative proportion of omega and ECR-1 in the different solids has been monitored by X-ray diffraction (XRD) and solid-stare nuclear magnetic resonance (NMR). 23Na NMR of calcined rehydrated solids was found to be particularly adapted to discriminate ECR-1 from zeolites omega in MAZ/EON mixtures with poorly resolved XRD patterns.

Mots clés: Zeolite omega; ECR-1; synthesis; nuclear magnetic resonance; structure

Domaines: Catalyse; Chimie

Corentin Chatelard, Mathias Dodin, Raquel Martinez-Franco, Alain Tuel. Di- and trioxacyclohexane as structure directing molecules in the synthesis of zeolites omega and ECR-1. Microporous and Mesoporous Materials, 2021, 318, pp.111015. ⟨10.1016/j.micromeso.2021.111015⟩. ⟨hal-03171990⟩