MIL-101(Cr) has drawn much attention due to its high stability compared with other metal-organic frameworks. In this study, three trace flue gas contaminants (H2O, NO, SO2) were each added to a 10 vol% CO2/N2 feed flow and found to have a minimal impact on the adsorption capacity of CO2. In dynamic CO2 regeneration experiments, complete regeneration occurred in 10 min at 328 K for temperature swing adsorption-N2-stripping under a 50 cm3/min N2 flow and at 348 K for vacuum-temperature swing adsorption at 20 KPa. Almost 99% of the pre-regeneration adsorption capacity was preserved after 5 cycles of adsorption/desorption under a gas flow of 10 vol% CO2, 100 ppm SO2, 100 ppm NO, and 10% RH, respectively. Strong resistance to flue gas contaminants, mild recovery conditions, and excellent recycling efficiency make MIL-101(Cr) an attractive adsorbent support for CO2 capture.

The adsorption/desorption kinetics of carbon dioxide on tetraethylenepentamine (TEPA) impregnated industrial grade multiwalled carbon nanotubes (IG-MWCNTs) was investigated to obtain insight into the underlying mechanisms on the fixed bed. After evaluating four kinetic models for CO 2 adsorption at various adsorption temperatures, CO 2 partial pressure, and amine loadings, it was found that Avrami's fractional-order kinetic model provided the best fitting for the adsorption behavior of CO 2 . In order to find the optimal regeneration method, three desorption methods were evaluated for the regeneration of solid sorbents. The activation energy E a of CO 2 adsorption/desorption was calculated from Arrhenius equation and used to evaluate the performance of the adsorbent. The E a decreased with increasing CO 2 concentration, indicating that CO 2 adsorption of amine-functionalized IG-MWCNTs is possibly intraparticle controlled. Meanwhile, because of the energy input of a vacuum pump, E a for the vacuum swing regeneration method was less than that for temperature swing regeneration.

The major drawback of aqueous alkanolamine-based CO2 capture processes is the high energy penalty for regeneration. To overcome this weakness, we studied the absorption of CO2 with amines dissolved in nonaqueous solvents. It was observed that triethylenetetramine (TETA) dissolved in ethanol produces a solid precipitate after absorption, which can then be easily separated and regenerated. As a comparison, a TETA/water solution does not form any precipitate after absorbing CO2. The TETA/ethanol solution offers several advantages for CO2 capture in absorption rate, absorption capacity, and absorbent regenerability. Both the rate and capacity of CO2 absorption with the TETA/ethanol solution were significantly higher than with a TETA/water solution, because ethanol not only promotes the solubility of CO2 in the liquid phase but also facilitates the chemical reaction between TETA and CO2. This approach was able to capture 81.8% of the absorbed CO2 in the solid phase as TETA-carbamate. In addition, results show that the decomposition of TETA-carbamate can be completed at 90 °C. Moreover, the cycling absorption/regeneration runs of the TETA/ethanol solution display a relatively stable absorption performance.

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An efficient access to prepare microgels from polyrotaxanes (PRXs) with characteristic thermoresponsiveness and photocontrolled degradation is reported. The microgels were formed by cross-linking the thermally collapsed spherical aggregates from thermoresponsive cyclodextrin PRXs in aqueous solutions above their phase transition temperatures through reaction of glutaraldehyde with acylhydrazine moieties to form the dynamic arylhydrazones. These microgels have uniform spherical morphologies with controllable sizes and tunable cross-linking densities, which retained characteristic thermoresponsive properties in water with cross-linking density-dependent thermally induced deswelling behavior. The spreading and deformation behavior of the microgels on solid substrates was investigated by AFM, which was found to be dominated by the cross-linking density. On the basis of the mechanically interlocked architecture, these cross-linked PRX microgels were stably dispersed in water but can be quickly degraded into small components upon UV cleavage of bulky stoppers. These photodegradable thermoresponsive microgels with dynamic cross-linked structures would hold great potential for biomedical and sensing applications.