Higher hydrocarbons in natural gas must be removed for safe storage, transport, and application of natural gas. Considering C3H8 and CH4 are nonpolar molecules, electrostatic interactions between C3 and MOFs are relatively weak, while they could be sensitive to the van der Waals interactions. Thus, it is an effective method to greatly enhance the separation performance by improving the van der Waals interactions through tuning the pore size of MOFs. Herein, we synthesized a series of isostructural Zr-MOFs with different pore sizes, and the separation performances of these materials for C3/C1 were systematically studied. The results indicate that pore size plays an important role in the C3 storage and C3/C1 separation in MOFs. Specifically, Zr-BPDC with large surface area and pore volume has the highest C3H8 and C3H6 adsorption capacity (159.2 cc/g and 161.5 cc/g at 298 K 1 bar, respectively), while Zr-FUM with the smallest surface area and pore volume has the highest adsorption heat for C3 as well as C3/C1 selectivities (292.0 and 242.2 at 298 K and 1 bar for C3H8/CH4 and C3H6/CH4, respectively) among the five Zr-MOFs. In addition, a defective structure in MOFs can largely improve C3 adsorption capacity for its higher surface area and pore volume, while functional groups in Zr-MOF will not obviously affect the C3 adsorption and C3/C1 separation performance. This work shows that van der Waals interactions in MOFs are predominantly for C3 adsorption and C3/C1 separation, and it can be efficiently tuned by changing the surface area and pore volume in MOFs. More importantly, this information could help design and synthesize a novel adsorbent to separate C3/C1 mixtures.

Separation of hydrogen isotopes is of great importance to produce highly pure hydrogen isotopes for numerous applications, which is however very difficult because of their almost identical thermodynamic properties. Adsorptive separation is considered as a simple, highly efficient, and cost-effective technique compared to the traditional methods, where the key is the suitable adsorbent. Herein, SIFSIX-3-Zn was screened out from the reported metal-organic frameworks (MOFs), exhibiting high selectivities for a D/H mixture by quantum sieving effect. Advanced cryogenic thermal desorption spectroscopy confirms the calculation results, indicating that the selectivities for a 1:1 D/H mixture at 20 K are larger than the values reported so far; especially, it shows a record value of 53.8 at 25 kPa. This demonstrates that this MOF is a promising candidate for highly effective hydrogen isotope separation.

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Considering the small amount of CO2 as a contaminant in industrial gas mixtures, developing CO2‐selective adsorbents exhibit advantages in directly obtaining pure C2H2 in one‐step to reduce the energy consumption. However, it is still a great challenge due to the essential molecular feature of C2H2, including the triple bond and high polarizability. Herein, a simple but effective CO2‐facilitated transport strategy is presented to realize the overwhelming adsorption of CO2 over C2H2 by constructing core–shell composite structures using ionic liquid (IL) and metal‐organic framework (MOF). With the aid of excellent solubility of CO2 in IL and almost total exclusion of C2H2, the obtained materials boost molecular sieving‐based separation of CO2/C2H2. Density functional theory calculations combining molecular dynamic simulations revealed the solution‐diffusion mechanism for CO2, which is rarely reported in solid adsorbents. Ideal adsorbed solution theory selectivity for CO2/C2H2 with 1/1 and 1/3 volume ratios can reach over 104 and 4000 at 100 kPa with a high CO2 uptake of 40.3 cm3 g−1, superior to those of the reported materials so far. More importantly, this solution‐based separation strategy can avoid the difficulty for precise control of the regulation of adsorbent structure, which may be beneficial to practical production.

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