1 research outputs found
Layered Double Hydroxide Nanoparticles/Microparticles (Mg/Al = 2) as Adsorbents for Temperature Swing Adsorption: Effect of Particle Size on CO<sub>2</sub> Gas Evolution Behavior
Mg–Al
layered double hydroxide (LDH, Mg/Al ≈ 2) nanoparticles/microparticles
with systematically controlled sizes were prepared using a hydrothermal
method, and their performance as CO2 adsorbents for temperature
swing adsorption (TSA) cycling was investigated. During continuous
heating, gas evolution occurred in three distinct steps for all samples.
During the second step of the multistep structural transformations
(i.e., partial dehydroxylation of the layers followed by the coordination
of carbonate ions to the metal ions), relatively large amounts of
CO2 were evolved without the collapse of the layered crystal
structure, whereas most of the interlayer CO32– ions were retained in the interlayer spaces. The amount of CO2 evolution increased as the particle size decreased. Subsequently,
the amount of CO2 desorption was measured over repeated
TSA cycles in the temperature range 463–603 K. All samples
exhibited considerable CO2 desorption capacities, wherein
water vapor enhanced the performance. In situ Fourier
transform infrared spectroscopy revealed that the adsorption–desorption
cycles were almost reversible. A slight change in the interlayer distance
detected by in situ X-ray diffraction suggested that
the insertion and removal of some carbonate species partly occurred
in the interlayer spaces of the LDHs. The present study indicates
the potential of LDH nanoparticles/microparticles for TSA adsorbents