Open Access
Determination of hazardous vapors from the thermal decomposition of organochlorinated silica xerogels with adsorptive properties
(Elsevier, 2024) Rosales Reina, María Beatriz; Cruz Quesada, Guillermo; Pujol, Pablo; Reinoso, Santiago; Elosúa Aguado, César; Arzamendi Manterola, Gurutze; López Ramón, María Victoria; Garrido Segovia, Julián José; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
The incorporation of organic groups into sol-gel silica materials is known to have a noticeable impact on the properties and structure of the resulting xerogels due to the combination of the properties inherent to the organic fragments (functionality and flexibility) with the mechanical and structural stability of the inorganic matrix. However, the reduction of the inorganic content in the materials could be detrimental to their thermal stability properties, limiting the range of their potential applications. Therefore, this work aims to evaluate the thermal stability of hybrid inorganic-organic silica xerogels prepared from mixtures of tetraethoxysilane and organochlorinated triethoxysilane precursors. To this end, a series of four materials with a molar percentage of organochlorinated precursor fixed at 10%, but differing in the type of organic group (chloroalkyls varying in the alkyl-chain length and chlorophenyl), has been selected as model case study. The gases and vapors released during the thermal decomposition of the samples under N2 atmosphere have been analyzed and their components determined and quantified using a thermogravimetric analyzer coupled to a Fourier-transform infrared spectrophotometer and to a gas chromatography-mass spectrometry unit. These analyses have allowed to identify up to three different thermal events for the pyrolysis of the organochlorinated xerogel materials and to elucidate the reaction pathways associated with such processes. These mechanisms have been found to be strongly dependent on the specific nature of the organic group.
Open Access
A simple approach to develop tailored mesoporosity in nanostructured heteropolysalts
(Wiley, 2017) Alcañiz Monge, Juan; Trautwein, Guido; El Bakkali, Bouchra; Reinoso, Santiago; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
In this study, we describe a very simple approach to the development of tailored mesoporosity in any nanostructured heteropolysalt with control over both the mesoporous volume and the pore size. This approach, which consists in the treatment of a solid microporous precursor with a basic agent, has been tested on the ammonium salt of the Keggin‐type [PMo12O40]3− heteropolyanion and constitutes a novel procedure for the preparation of mesoporous solids with no precedents. The results obtained in this study allow two main conclusions to be drawn: 1) the micro‐ and mesoporous structures in the heteropolysalt nanoparticles are independent from each other and 2) the development of mesoporosity in the solid material must be related to a process of alkaline degradation within the core of the nanocrystals that aggregate into the particles. These results afford valuable additional information to the present model of porosity that has been established for heteropolysalts.

Reinoso, Santiago

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