Scientific Results

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-Rodríguez 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, 1H MAS, 29Si HPDEC MAS NMR and N2 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      Pages from: 7020  to: 7033

KeyWords: ultrasounds, mesoporous materials, microwave chemistry, MCM-41
DOI: 10.1039/c3ta15078j

Citations: 14
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