Ionosilica-based anion exchangers for low-temperature thermochemical storage of energy under mild conditions of adsorbent regeneration and saturation

Abstract

Three ionosilica materials have been tested for low-temperature thermochemical storage of energy under mild conditions of adsorbent regeneration and saturation. The previous synthesis procedures were adapted to prepare materials possessing an organosilica framework with silylated cationic blocs and Cl-, HSO4-, SO4 2anions in various proportions as extra-framework compensating counter-ions. Transmission and Scanning Electron Microscopy, Wavelength Dispersive X-Ray Fluorescence, Energy Dispersive X-ray Spectroscopy, Thermogravimetric analysis, adsorption of gaseous nitrogen at 77 K, 29 Si Solid-State Nuclear Magnetic Resonance spectroscopy were employed to establish the key characteristics of the three ionosilica samples in terms of elemental composition, particle morphology and textural properties, thermal stability and regenerability, or variability of surface activity during repeated hydrationdehydration cycles. Their capacity to adsorb water vapor at cool and moderate ambient temperatures after incomplete surface drying was demonstrated by means of the scanning microscopy operating in low-vacuum mode at 275 K, or more precisely by measuring the water adsorption isotherms at 313 K and the related differential heats under static conditions. Finally, flow calorimetry operating in the moist-gas flow mode was used to measure the integral heat accompanying the adsorption of water vapor at its partial pressure of 2.8 kPa and 296 K as well as the kinetics of heat release in three drying-saturation cycles. After a drying procedure carried out under helium flow at 353 K, the thermal performance of two ionosilica samples containing both HSO4and SO4 2counter-ions was sufficient enough to consider them as potential adsorbents for auxiliary space heating in homes, small businesses, or public buildings.

Heat Release Kinetics upon Water Vapor Sorption Using Cation-Exchanged Zeolites and Prussian Blue Analogues as Adsorbents: Application to Short-Term Low-Temperature Thermochemical Storage of Energy

“…It appears clear that various materials attain their optimal performance under particular operating conditions, but none of them really stands out significantly above the others. In consequence, the current trend is either to still search for completely new adsorbents (e.g., [11][12][13][14][15]) or to find optimal operating conditions for the existing materials.…”

Controlled synthesis and osmotic properties of ionosilica nanoparticles

“…These results corroborate with N/S atomic ratios from elemental analysis. 13 C NMR simulations with Chemdraw ultra 12.0 software considering an atomic ratio N/S = 9 led to a well-fitting model with the real CP-MAS { 1 H}- 13 C NMR spectrum of the purified sample (figure 5d). All together, the characterization of the INPs via CP-MAS { 1 H}- 13 C NMR spectroscopy confirms the smooth sol-gel transformation of precursor 1 and the formation of ionosilica phases from this compound.…”

“…The chemical and physico-chemical polyvalence of ionosilicas is related to the huge number of possible cation-anion combinations. As an example, the hydrophilicity of ionosilicas principally depends on the nature of the counter-anion [12,13]. Halide anions generate relatively hydrophilic ionosilicas whereas fluorinated anions such as bis-trifluoromethanesulfonimide (NTf2 -) give rise to less hydrophilic materials [12].…”

“…It is possible to tune the hydrophilicity of ionosilicas from highly to moderately hydrophilic. The high hydrophilicity of ionosilicas opens the route towards applications for example in the area of thermochemical heat storage [13]. Additionally, the high number of ionic groups that are immobilized in a reduced space gives rise to unusual confinement effects, which cannot be achieved in conventional non-ionic porous materials [14].…”

Quaternary Ammonium-Based Ionosilica Hydrogels as Draw Solutes in Forward Osmosis

“…Indeed, ionosilicas are relatively inexpensive materials that can be obtained in a kilogram scale from standard chemicals such as (3-chloropropyl)trimethoxysilane and (3-aminopropyl)trimethoxysilane. The availability of ionosilicas in large quantities allows applications of these phases on a pilot scale in chromatography, anion exchange and thermochemical heat storage [ 28 ]. Ionosilicas are therefore not only laboratory curiosities, but easily accessible and highly polyvalent materials with a broad application spectrum.…”