Synthesis and characterization of ultramicroporous silica xerogels

Echeverría, Jesús C.; Estella, Juncal; Barbería, Vanesa; Musgo, Javier; Garrido, Julián

doi:10.1016/j.jnoncrysol.2009.11.044

Cited by 29 publications

(14 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This is because the N 2 retention mechanism within the narrow micropores (r pores /r adsorbate ~ 1.1) is based on the overlap of pore wall potentials (∅ < 0.7 nm). This behavior was also described in analogous non-chlorinated xerogels [ 56 ].…”

Section: Resultssupporting

confidence: 66%

Novel Organochlorinated Xerogels: From Microporous Materials to Ordered Domains

et al. 2021

Self Cite

View full text Add to dashboard Cite

Hybrid silica xerogels combine the properties of organic and inorganic components in the same material, making them highly promising and versatile candidates for multiple applications. They can be tailored for specific purposes through chemical modifications, and the consequent changes in their structures warrant in-depth investigation. We describe the synthesis of three new series of organochlorinated xerogels prepared by co-condensation of tetraethyl orthosilicate (TEOS) and chloroalkyltriethoxysilane (ClRTEOS; R = methyl [M], ethyl [E], or propyl [P]) at different molar ratios. The influence of the precursors on the morphological and textural properties of the xerogels was studied using 29Si NMR (Nuclear Magnetic Resonance), FTIR (Fourier-Transform Infrared Spectroscopy), N2, and CO2 adsorption, XRD (X-ray Diffraction), and FE-SEM (Field-Emission Scanning Electron Microscopy). The structure and morphology of these materials are closely related to the nature and amount of the precursor, and their microporosity increases proportionally to the molar percentage of ClRTEOS. In addition, the influence of the chlorine atom was investigated through comparison with their non-chlorinated analogues (RTEOS, R = M, E, or P) prepared in previous studies. The results showed that a smaller amount of precursor was needed to detect ordered domains (ladders and T8 cages) in the local structure. The possibility of coupling self-organization with tailored porosity opens the way to novel applications for this type of organically modified silicates.

show abstract

Section: Resultssupporting

confidence: 66%

Novel Organochlorinated Xerogels: From Microporous Materials to Ordered Domains

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…For this reason, Figure 8 shows CO2 adsorption isotherms at 273 K on all synthesized AC materials together with the corresponding N2 adsorption isotherms at 77 K. Even if limitations in the absolute pressure bearable by the adsorption instrument make it possible to reach only CO2 relative pressures < 0.03, this kind of data can usually be modelled with the Dubinin-Radushkevich (DR) equation [34,35]. Indeed, the DR model allows the extrapolation (as model parameter) of the total micropore volume of the adsorbents, as reported in Table 3.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of Activated Carbon Foam from Polymerization of Furfuryl Alcohol Activated by Zinc and Copper Chlorides

Cepollaro

Caputo

Cimino

et al. 2020

View full text Add to dashboard Cite

Polymerization of furfuryl alcohol carried out using ZnCl2 or CuCl2 as Lewis acid activators was investigated by exploring various synthesis parameters in order to produce activated carbons with different porosity and metal load. The temperature of polymerization was changed according to Lewis acidity strength of the two metal chlorides: 0 °C for CuCl2 and 80 °C for ZnCl2. The polymer obtained was pyrolyzed under pure He flow or under 1000 ppm O2/He flow at 600 or 850 °C in order to produce activated carbons with specific textural features. The load and nature of the residual metal after pyrolysis were determined by ICP and XRD analyses, respectively. Copper was mostly preserved even at high pyrolysis temperature in contrast to zinc, which was almost totally lost at 850 °C. A foamy structure was detected by SEM analysis for all samples. Textural properties were determined by both N2 and CO2 physisorption; surface areas and pore size distributions were evaluated according to BET, DFT and DR models. The polymerization activated by ZnCl2 produced carbons with larger surface areas were also related to the presence of some mesopores, whereas CuCl2 promoted the prevailing formation of narrow micropores, making these materials particularly suited to H2 storage applications.

show abstract

“…At 1173 K, the groups mentioned above were removed, as were carbonyls, phenolics, ethereal groups, and some quinones. Treatment with the HNO 3 solution generated a greater amount of oxygenated surface groups, such as carboxylic, lactonic, and phenolic groups, which made the entrance of the hexane to the porous network difficult and even generated inaccessibility to certain regions of the solid in the edges of the graphene layers [ 42 , 43 , 44 , 45 ].…”

Section: Resultsmentioning

confidence: 99%

Study of Hexane Adsorption on Activated Carbons with Differences in Their Surface Chemistry

2018

View full text Add to dashboard Cite

The study of aliphatic compounds adsorption on activated carbon can be carried out from the energetic change involved in the interaction; the energy values can be determined from isotherms or by the immersion enthalpy. Vapor phase adsorption isotherms of hexane at 263 K on five activated carbons with different content of oxygenated groups and the immersion enthalpy of the activated carbons in hexane and water were determined in order to characterize the interactions in the solid–liquid system, and for calculating the hydrophobic factor of the activated carbons. The micropore volume and characteristic energy from adsorption isotherms of hexane, the BET (Brunauer–Emmett–Teller) surface area from the adsorption isotherms of N2, and the area accessible to the hexane from the immersion enthalpy were calculated. The activated carbon with the lowest content of oxygenated groups (0.30 µmolg−1) and the highest surface area (996 m2g−1) had the highest hexane adsorption value: 0.27 mmol g−1; the values for Eo were between 5650 and 6920 Jmol−1 and for ΔHim were between −66.1 and −16.4 Jg−1. These determinations allow us to correlate energetic parameters with the surface area and the chemical modifications that were made to the solids, where the surface hydrophobic character of the activated carbon favors the interaction.

show abstract

Synthesis and characterization of ultramicroporous silica xerogels

Cited by 29 publications

References 22 publications

Novel Organochlorinated Xerogels: From Microporous Materials to Ordered Domains

Novel Organochlorinated Xerogels: From Microporous Materials to Ordered Domains

Synthesis and Characterization of Activated Carbon Foam from Polymerization of Furfuryl Alcohol Activated by Zinc and Copper Chlorides

Study of Hexane Adsorption on Activated Carbons with Differences in Their Surface Chemistry

Contact Info

Product

Resources

About