New synthesis routes and catalytic applications of ferrierite crystals. Part 2: the effect of OSDA type on zeolite properties and catalysis

Enrico Catizzone (1) , Massimo Migliori (2) , Tzonka Mineva (3) , Stijn van Daele (4) , Valentin Valtchev (5) , Girolamo Giordano (2)

1 ENEA - Italian National agency for new technologies, Energy and sustainable economic development [Frascati]
2 Unical - Università della Calabria [Arcavacata di Rende]
3 ICGM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
4 [TRTF] - Total Research and Technology Feluy
5 LCS - Laboratoire catalyse et spectrochimie

Tailoring of physicochemical properties of synthetic zeolites is of paramount importance when these materials are applied as heterogenous catalysts. In this work, the effect of the synthesis system and in particular of the organic structure directing agent (OSDA) on acidity, crystal morphology, and catalytic behavior of FER-type materials is studied. FER-type zeolites with similar Si/Al ratio and crystal size range 0.3-15 µm are synthesized by changing OSDA type or by adding surfactant. A crystallization kinetic analysis shows that the stability of the zeolitic phase strongly depends on the OSDA type. In particular, the crystallization time strongly affects the purity of the FER phase when tetrahydrofuran is used as a template. Furthermore, it is found that long amines as 1,8-diaminooctane can play a role of OSDA obtaining highly crystalline FER-type crystals and with a high Lewis acid sites concentration. FT-IR and 27 Al-NMR analyses show that all of the synthesized samples possess different Lewis acid sites concentration associated with extra-framework Al-OH species that are not detected by NMR analysis. Catalytic tests in methanol-to-dimethyl ether reaction reveal that synthesized samples exhibit different catalytic behavior. In particular, large (10-15 µm) FER-type catalyst synthesized with tetrahydrofuran suffer deactivation caused by a higher carbon deposit level. On the contrary, nano-sized FER-type crystals, prepared by using pyrrolidine as OSDA and a surfactant, exhibits high selectivity and considerable resistance to coke deposition.

Mots clés: Ferrierite zeolite; synthesis; crystal morphology; Brønsted-Lewis acidity; methanol conversion

Domaines: Chimie

Enrico Catizzone, Massimo Migliori, Tzonka Mineva, Stijn van Daele, Valentin Valtchev, et al.. New synthesis routes and catalytic applications of ferrierite crystals. Part 2: the effect of OSDA type on zeolite properties and catalysis. Microporous and Mesoporous Materials, 2020, 296, pp.109988. ⟨10.1016/j.micromeso.2019.109988⟩. ⟨hal-03035139⟩