Reversible Trap−Release of CO₂ by Polymers Bearing DBU and DBN Moieties

Abstract

Copolymers bearing DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) and DBN (1,5-diazabicyclo[4.3.0]non-5-ene) moieties fixed carbon dioxide under atmospheric pressure. The copolymers bearing DBN moieties fixed carbon dioxide faster than those bearing DBU moieties owing to the lower steric hindrance around the imine structure. These copolymers held trapped CO 2 under a N 2 flow at 25 °C, whereas the corresponding lowmolecular weight amidines release trapped CO 2 under the same conditions. The trapped CO 2 in the copolymers was quantitatively released by a N 2 flow at 120 °C. The CO 2 trapping efficiency of a copolymer bearing DBN moieties is competitive with that of an amidine-containing polymer, whereas the preparative method for the copolymer bearing DBN is easier. The higher CO 2 trapping abilities of the DBN derivatives were supported by computational calculation.

Adsorbent Materials for Carbon Dioxide Capture from Large Anthropogenic Point Sources

“…Pis [244] determined that amine-impregnated activated carbons reached equilibrium in approximately 40 min. Measurements by Endo [252] indicated that styrene and DBN copolymers did not reach equilibrium for hundreds of minutes. These results were all measured by TGA and may be inapplicable to most process configurations where gas is fed through adsorbents and not past or around them (vide infra, section 5).…”

“…Beckman, [250] Barron, [245] and Pis [244] observed linear decreases in the capacities of their adsorbents as operating temperature increased from room temperature to moderately elevated temperatures. Snape [253] measured a 56 % decrease in capacities of UF and MF resins when the operating temperature was increased from 298 to 348 K. Endo [252] measured a 35 % decrease in the capacity of a styrene and DBN copolymer when the operating temperature was increased from 298 K to 338 K. Li [249] determined the capacity of PEI and ECH copolymer to have a non-linear temperature dependence from 303 to 363 K, with the capacity leveling off at temperatures above 328 K. This suggests that diffusion limitations existed in the adsorbent, because at higher temperatures the increased diffusion of CO 2 would cause a higher adsorption capacity, as often seen for amine-impregnated silicas (see section 3.1.6).…”

“…Endo [252] used a similar approach as Beckman to prepare amine containing copolymers. They synthesized copolymers from VBC and either styrene or dimethylacrylamide (DMA) Figure 39.…”

“…Beckman [250] measured CO 2 capacities of 2.16 and 2.62 mmol CO 2 g À1 for a cross-linked copolymer of EDA-modified VBC, and DVB and a linear polymer of EDA-modified VBC and styrene using TGA with a 14 % CO 2 feed. Endo [252] measured CO 2 capacities of 0.76 and 0.39 mmol CO 2 g À1 for a copolymer of styrene and DBN and a copolymer of DMA and DBN, respectively, at 298 K using TGA with a 100 % CO 2 feed. Beckman [251] also reported the capacity as a function of alkyl chain length of styrene and VBC copolymers aminated with diamines containing alkyl spacers of length n = 2 to 10.…”

Fabrication of CO2 Facilitated Transport Channels in Block Copolymer through Supramolecular Assembly

“…As we know, amidine groups have reversible reaction with CO 2 in the presence of water forming the intermediate compound carbonate [19][20][21][22][23]. The intermediate compound can be delivered from the high potential energy side to the low potential energy side.…”