Diffusion Kinetics of CO₂, CH₄, and their Binary Mixtures in Porous Organic Cage CC3

Abstract

The sorption kinetics of single-and binary-component mixtures of CO 2 and CH 4 in porous organic cage (POC) CC3 was investigated by the zero-length column (ZLC) technique for the purpose of understanding the experimental diffusivity values of light gases through this novel branch of porous molecular solids. The intracrystalline diffusivities were measured at 25 °C, and a binary-gas ratio of 10/90 CO 2 /CH 4 was utilized in order to mirror concentrations of CO 2 and CH 4 in natural gas. The diffusion time constants were measured and then compared in order to investigate the effects of coadsorption for binary-gas mixtures and were also compared against molecular simulation diffusion values that have been reported in other works. The diffusion time constants measured for CO 2 for single-and binary-component trials were found to be 1.05 × 10 −3 and 8.70 × 10 −4 s −1 , respectively, whereas for CH 4 , these measured values were estimated to be 1.10 × 10 −3 and 1.03 × 10 −3 s −1 , respectively. Moreover, the diffusion of CO 2 revealed the presence of surface resistances due to adsorbent pore window size limitations that hinder the transport of CO 2 molecules upon diffusion. The findings of this study provide novel experimental kinetic characterizations of the sorption kinetics of CO 2 and CH 4 through CC3 for the separation of CO 2 from natural gas.

Boosting the Productivity of Electrochemical CO2Reduction to Multi‐Carbon Products by Enhancing CO2Diffusion through a Porous Organic Cage

“…According to a previous report, [37] CC3 exhibits tetrahedral cages, and packs in a window‐to‐window arrangement (Figure 1A). From the scanning electron microscope (SEM) image, we can observe that the CC3 exhibits the octahedral morphology (Figure S2), which was consistent with a previous report [41] …”

“…From the scanning electron microscope (SEM) image, we can observe that the CC3 exhibits the octahedral morphology (Figure S2), which was consistent with a previous report. [41] The CuO-nr/CC3 was first prepared by blending CuO-nr and CC3 in dichloromethane with the assistance of sonication. The CuO-nr and CC3 were mixed uniformly, and the CC3 was reassembled on the surface of CuO-nr, the average particle size of the CC3 was about 80 nm (Figure S3, the content of CC3 was 10 wt %).…”

“…The CuO‐nr was prepared according to our previous report (Figure S1) [28] . The CC3 was synthesized by the condensation reaction of 1,3,5‐triformylbenzene with ( R , R )‐1,2‐diaminocyclohexane in a [4+6] cycloimination [41] (see methods for experimental details). According to a previous report, [37] CC3 exhibits tetrahedral cages, and packs in a window‐to‐window arrangement (Figure 1A).…”

“…[39] In particular, POCs have been widely used for gas adsorption and separation, due to the fact that they exhibited diverse cage structures with varied gas sorption properties. [40,41] For example, as a representative of POCs, CC3 showed good performance in separating CO 2 from mixed gas, as the pores of CC3 can be used as a CO 2 channel. [42] In addition, the CO 2 can be trapped by the POCs under water-based electrolytes, [43] because the POCs exhibited strong adsorption of CO 2 .…”

“…POCs are covalently bonded organic cages that assemble into unique crystalline structures, leading to diverse applications [39] . In particular, POCs have been widely used for gas adsorption and separation, due to the fact that they exhibited diverse cage structures with varied gas sorption properties [40, 41] . For example, as a representative of POCs, CC3 showed good performance in separating CO 2 from mixed gas, as the pores of CC3 can be used as a CO 2 channel [42] .…”