title: Effective and Selective Trapping of Volatile Organic Sulfur Derivatives by Montmorillonite Intercalated with a μ-oxo Fe(III)-Phenanthroline Complex.
abstract: The μ-oxo Fe(III)-phenanthroline complex [(OH2)3(Phen)FeOFe(Phen) (OH2)3]+4intercalated in montmorillonite provides a stable hybrid material. In this study, the ability and efficiency of this material to immobilize thiols in gas phase, acting as a trap at the solid-gas interface, were investigated. Aliphatic thiols containing both hydrophilic and hydrophobic end groups were chosen to test the selectivity of this gas trap. DR-UV-vis, IR, elemental analysis, thermal analysis and evolved gas mass spectrometry, X-ray powder diffraction, and X-ray absorption spectroscopy techniques were employed to characterize the hybrid material before and after thiol exposure and to provide information on the entrapping process. Thiol immobilization is very large, up to 21% w/w for heptanethiol. In addition, evidence was obtained that immobilization occurs through the formation of a covalent bond between the iron of the complex and the sulfur of the thiol. This provides an immobilization process characterized by a higher stability with respect to the methods based on physi-adsorption. Thiol immobilization resulted thermally reversible at least for 20 adsorption/desorption cycles. Unlike standard desulfurization processes like hydrotreating and catalytic oxidation which work at high temperatures and pressures, the present system is able to efficiently trap thiols at room temperature and pressure, thus saving energy. Furthermore, we found that the selectivity of thiol immobilization can be tuned acting on the amount of complex intercalated in montmorillonite. In particular, montmorillonite semisaturated with the complex captures both hydrophobic and hydrophilic thiols, while the saturated montmorillonite shows a strong selectivity toward the hydrophobic molecules.
authors.affiliation: Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia , Via Campi 103, I-41125 Modena, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Bernini
authors.affiliation: Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia , Via Campi 103, I-41125 Modena, Italy.
authors.forename: Elena
authors.identifier: http://orcid.org/0000-0002-2933-4405
authors.initials: E
authors.lastname: Castellini
authors.affiliation: Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia , Via Campi 103, I-41125 Modena, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Malferrari
authors.affiliation: SpLine, Spanish CRG BM25 Beamline at the ESRF , 6 Jules Horowitz, F-38043 Grenoble, France.|Instituto de Ciencia de Materiales de Madrid (ICMM), CSIC , c. Sor Juan Inés de la Cruz 3, E-28049 Madrid, Spain.
authors.forename: German Rafael
authors.initials: GR
authors.lastname: Castro
authors.affiliation: Instituto Andaluz de Ciencias de la Tierra (IACT) CSIC, Universidad de Granada , Av.da Las Palmeras 4, 18100 Granada, Spain.
authors.forename: Claro Ignacio
authors.initials: CI
authors.lastname: Sainz Díaz
authors.affiliation: Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia , Via Campi 103, I-41125 Modena, Italy.
authors.forename: Maria Franca
authors.identifier: http://orcid.org/0000-0002-7526-9931
authors.initials: MF
authors.lastname: Brigatti
authors.affiliation: Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia , Via Campi 103, I-41125 Modena, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Borsari
keywords: heptanethiol; iron−phenanthroline complex; mercaptohexanol; montmorillonite; solid−gas interface; sulfur trapping; thiol