Wiggling Mesopores Kinetically Amplify the Adsorptive Separation of Propylene/Propane

Abstract

Adsorptive separation is an appealing technology for propylene and propane separation; however, the challenge lies in the design of efficient adsorbents which can distinguish the two molecules having very similar properties. Here we report a kinetically amplified separation by creating wiggling mesopores in structurally robust carbon monoliths. The wiggling mesopores with alternating wide and narrow segments afford a surface area of 413 m2 g−1 and a tri‐modal pore size distribution centered at 1.5, 4.2 and 6.6 nm, respectively. The synergistically kinetic and equilibrium effects were observed and quantitatively assessed, which together ensured a remarkable propylene/propane selectivity up to 39. This selectivity outperformed not only the available carbon adsorbents but also highly competitive among the dominated crystalline porous adsorbents. In addition, the wiggling mesoporous carbon adsorbent showed excellent dynamical separation stability, which ensured its great potential in practical molecular separations.

Recent Advances in the Development of Metal–Organic Frameworks for Propylene and Propane Separation

“…Importantly, because C 3 H 6 is selectively adsorbed via weak hydrogen bonding interactions, the adsorption heat (27.5 kJ mol –1 at zero loading) is prominently lower than that of other equilibrium-based adsorbents, which means ZnAtzPO 4 can be regenerated under milder conditions with less energy cost. Later, the equilibrium-kinetics synergetic effect is also observed with an elaborately designed carbon material MC-wiggle for C 3 H 6 /C 3 H 8 separation, verifying that the strategy can be applied to various materials, including but not limited to MOFs.…”

“…76,77 Because of the partial dependence on thermodynamic effect, the mentioned synergetic strategy not only proves an efficient way to realize the highly selective gas separation but also brings the possibility to enhance the gas separation in a more energyefficient way. 78 Ding et al recently reported the separation of C 3 H 6 and C 3 H 8 with an ultramicroporous MOF ZnAtzPO 4 (Atz = 3-amino-1,2,4-triazole), 79 22 verifying that the strategy can be applied to various materials, including but not limited to MOFs.…”

“…Recently, adsorptive separation and membrane-based separation are receiving tremendous attention because their energy consumptions are comparable with one-third that of the conventional cryogenic distillation method or even less. − Porous materials are the core part in the adsorptive- and membrane-based approaches to realize high separation selectivity, gas capacity/permeability, and good stability. To date, traditional adsorbents like zeolites and carbon materials have been widely studied for the separation of C 3 H 6 and C 3 H 8 . − However, since these materials lack modular building units and are composed of monotonous elements, problems like poor structural diversity, difficulty to precisely control pore size, and high complexity in framework functionalization still hinder them from accurately discriminating the small differences between C 3 H 6 and C 3 H 8 (Table ). As a result, these materials seldom offer satisfactory separation selectivity and gas capacity at the same time.…”

Recent Advances in Carbon-Based Adsorbents for Adsorptive Separation of Light Hydrocarbons

“…Our group recently demonstrated a new strategy to create wiggling mesopores in monolithic carbon (MC-wiggle) through a perturbed self-assembly method [119]. By such nanoscale mesopore geometry engineering, we achieved a C 3 H 6 /C 3 H 8 separation selectivity of around 39.0 and a C 3 H 6 uptake of 2.6 mmol g -1 , which outperform not only the reported carbonaceous adsorbents but also the topperforming crystalline adsorbents like MOFs and zeolites.…”

Beyond the Selectivity-Capacity Trade-Off: Ultrathin Carbon Nanoplates with Easily Accessible Ultramicropores for High-Efficiency Propylene/Propane Separation

“…22 To address this issue, our group devised a family of carbon adsorbents with "wiggling" mesopores for C 3 H 6 /C 3 H 8 separation. 23 Transport of C 3 H 6 through these wiggling mesopores was far superior than the C 3 H 8 molecules. Although the adsorption selectivity was improved using a mesopore engineering strategy, the C 3 H 6 adsorption capacity still needed to be improved.…”