Surfactant recovery from mesoporous metal-modified materials (Sn-, Y-, Ce-, Si-MCM-41), by ultrasound assisted ion-exchange extraction and its re-use for a microwave in situ cheap and eco-friendly MCM-41 synthesis

Year: 2014

Authors: Gonzalez-Rivera J., Tovar-Rodriguez J., Bramanti E., Duce C., Longo I., Fratini E; Galindo-Esquivel I.R., Ferrari C.

Autors Affiliation: Chemical Engineering Department, University of Guanajuato, Noria Alta s/n 36050, Guanajuato, Gto, Mexico; National Research Council of Italy (C.N.R.), Istituto di Chimica dei Composti Organo Metallici (ICCOM) – UOS Pisa, Via G. Moruzzi 1, 56124 Pisa, Italy; Department of Chemistry and Industrial Chemistry, University of Pisa, Via Risorgimento 35, 56127 Pisa, Italy; National Research Council of Italy (C.N.R.), Istituto Nazionale di Ottica, (INO) – UOS Pisa, Via G. Moruzzi 1, 56124 Pisa, Italy; Department of Chemistry “Ugo Schiff” and CSGI, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy

Abstract: Different metal substituted (Y, Sn and Ce) MCM-41 materials were synthesized and detemplated by a low temperature surfactant removal methodology. All metal substituted materials showed an increase in the d(100) lattice parameter compared to the parent MCM-41 matrices. The increase depends on both the metal type and amount that is successfully incorporated by direct conventional hydrothermal synthesis. The metal modified MCM-41 materials were detemplated by an ultrasound assisted (US) ion-exchange process using methanol as the solvent (NH4NO3/US/MeOH). The effect of the ultrasound amplitude, extraction time and salt concentration were explored, and optimal values were determined for Y-MCM-41 detemplation (40 mM of NH4NO3, 60% of US amplitude and 15 min of adiabatic treatment). The removal percentage achieved with these values was in the following order: Y (97.7%) > Ce (94.4%) > Sn ;(92.1%) > Si (90.3%). Several techniques (SAXS, FTIR, TGA, H-1 MAS, Si-29 HPDEC MAS NMR and N-2 physisorption) demonstrated that the mesoporous materials keep their hexagonal structure and high surface area after the NH4NO3/US/MeOH surfactant extraction. Moreover, the thermal shrinkage of the structure was reduced in the following order: Si (0.6%) < Sn (4%) < Ce (5%) < Y (9%) < calcined samples (from 9 to 15%). The surfactant recovered was successfully recycled in a consecutive microwave assisted hydrothermal synthesis cycle (MW-HT). The synergy of different strategies (MW-HT synthesis, NH4NO3/US/MeOH surfactant removal and surfactant recovery) produces considerable time, energy and cost abatement, environmental impact reduction and promising scale up projections in the eco-friendly synthesis of MCM-41 materials. Journal/Review: JOURNAL OF MATERIALS CHEMISTRY A

Volume: 2 (19)      Pages from: 7020  to: 7033

More Information: The authors wish to acknowledge the National Council of Science and Technology (CONACYT Mexico, project CB-2010-158193) and the Consorzio per lo Sviluppo dei Sistemi a Grande Interfase (CSGI), for providing financial support. The authors would like to thank C. Lanza (INO-CNR), F. Pardini (INO-CNR) and Marco Vera (UAM-I) for their valuable technical support.
DOI: 10.1039/c3ta15078j

Citations: 19
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