Silica gel

About: Silica gel is a research topic. Over the lifetime, 22313 publications have been published within this topic receiving 325516 citations. The topic is also known as: Amorphous silica & Precipitated amorphous silica.

Effect of shrinkage on the modulus of silica gel

Abstract: The shear modulus of alkoxide-derived silica gels was measured during aging and drying; base- and acid-catalyzed gels were examined, and gave qualitatively similar results. There is a continual increase in shear modulus (G) during syneresis, which is most rapid for the first two weeks after gelation. If the gel is soaked in a liquid containing more water than the pore liquor, it shrinks and stiffens more rapidly; base-catalyzed gels exhibit phase separation (apparently from segregation of residual partially condensed TEOS). If evaporation is prevented, G only increases by a factor of ∼ 2 upon aging from 1 to 12 months. When the liquid is allowed to evaporate, G increases by about 3 orders of magnitude as the gel contracts by ∼ 50% linearly. There is an approximate exponential relation between G and the radial strain that applies about as well for samples aged in various solutions as for samples dried in air. The relation between G and strain (contraction) is nearly independent of drying rate when the linear strain exceeds ∼ 10%. The modulus of rupture rises by about 2.5 orders of magnitude during drying.

Development of silica‐gel‐supported polyethylenimine sorbents for CO2 capture from flue gas

Abstract: In order to reduce the sorbent preparation cost and improve its volume-based sorption capacity, the use of an inexpensive and commercially available silica gel was explored as a support to prepare a solid polyethylenimine sorbent (PEI/SG) for CO2 capture from flue gas The effects of the pore volume and particle size of the silica gels, molecular weight of polyethylenimine and amount of polyethylenimine loaded, sorption temperature and moisture in the flue gas on the CO2 sorption capacity of PEI/SG were examined The sorption performance of the developed PEI/SG was evaluated by using a thermogravimetric analyzer and a fixed-bed flow sorption system in comparison with the SBA-15-supported polyethylenimine sorbent (PEI/SBA-15) The best PEI/SG sorbent showed a mass-based CO2 sorption capacity of 138 mg-CO2/g-sorbent, which is almost the same as that of PEI/SBA-15 In addition, the PEI/SG gave a high volume-based sorption capacity of 83 mg-CO2/cm3-sorbent, which is higher than that of PEI/SBA-15 by a factor of 26 © 2011 American Institute of Chemical Engineers AIChE J, 58: 2495–2502, 2012

Dehydration of silica-aluminas monitored by high-resolution solid-state proton NMR

Abstract: Knowledge of the acid sites on silica-aluminas and zeolites has been addressed by various techniques. With a combination of multiple-pulse techniques and magic-angle spinning (MAS) one can obtain high-resolution /sup 1/H NMR spectra of solid samples. In this paper they report the initial results of a study of the dehydration of silica-alumina, silica gel, and ..gamma..-alumina by the /sup 1/H CRAMPS (combined rotation and multiple-pulse spectroscopy) NMR technique.