Calcium oxide is a known adsorbent for the capture of
carbon dioxide.
In this study, CaO-based sorbents were prepared using the precipitation
of solutions containing different anion precursors, including nitrate
NO3
– and chloride Cl–, by different alkaline precipitants. The sorbents prepared from
the precipitation of salt solutions by alkaline solutions under specific
precipitation conditions resulted in the excellent uptake capacity
for CO2. These sorbents formed as a fine powder with a
BET surface area (16.5 m2/g) and pore volume (0.35 cm3/g) showed almost 100% carbonation, at temperatures between
650 and 750 °C. Moreover, the carbonation proceeded predominantly
during an initial short period. Under numerous carbonation/calcination
cycles, these sorbents demonstrated a good reversibility. During a
17-cycle operation, the sorbents maintained a fairly high conversion
of 70% at 700 °C. As the carbonation/calcination cycles progress,
sorbent particles conglomerate to a loosely integrated lump resulting
in a greater mass transfer resistance for CO2 molecules
to reach the unreacted core of calcium oxide. It is observed that
grinding of the formed chunk to fine particles could recover the activity
of sorbent completely.
In this study, a novel approach for the synthesis of zeolite Y is described. The effect of varying the starting silica source on the purity of zeolite Y was investigated, while all other reaction parameters were kept constant. The purity of zeolite was expressed in terms of percent crystallinity obtained from the powder XRD. The silica sources were all powders of varying types (except for silica sol). To study the influence of the varying silica sources on the purity of the resulting zeolite Y, the best gel composition and synthesis condition for one batch were chosen. The gel composition was 4Na 2 O:1Al 2 O 3 :6SiO 2 :200H 2 O. The aging temperature and duration of aging were chosen as room temperature and 120 h, respectively. The synthesis temperature and synthesis time were 100 °C and 48 h. The experiments were all conducted in sealed 30 mL Teflon bottles. The extent to which the pure zeolite Y was formed depended on the BET specific surface area of the silica sources (ranging from 150 to 300 m 2 /g) but not on the synthesis conditions. This novel method for zeolite Y preparation allows one to eliminate the vigorous agitation step required for the preparation of a homogeneous silica solution, thereby simplifying the synthesis of zeolite Y in one single vessel.
Immobilizing amino acid ionic liquids
(AAILs) into a porous support
is a promising way to fabricate robust solid sorbents with high capacities
for CO2 capture. One of important factors to be evaluated
toward the practical use is the impact of water vapor in inlet gases
on the CO2 capture performance as real flue gases contain
some fraction of water vapor. In this study, CO2 sorption–desorption
experiments of supported 1-ethyl-3-methylimidazolium amino acid ([EMIM][AA])
IL sorbents on porous microspheres were conducted under dry and humidified
CO2 inlet conditions using a TGA-MS analysis system, and
their outcomes were compared with those of supported amino acids (AA)
sorbents. The presence of water vapor changed the CO2 sorption
behaviors depending on the sorbent types. In humidified CO2 inlet, the CO2 capture capacities of supported [EMIM][glycine]
and [EMIM][lysine] decreased as the adsorbed water hindered their
reaction with CO2, whereas the CO2 capture of
those with supported lysine and arginine increased, since water content
exerted a positive impact on the CO2 capture behavior.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.