High-Performance Carbon Molecular Sieves for the Separation of Propylene and Propane

Robust Two-Dimensional Hydrogen-Bonded Organic Framework for Efficient Separation of C1-C3 Alkanes

Separating natural gas to obtain high-quality C1-C3 alkanes is an imperative process for supplying clean energy sources and high valued petrochemical feedstocks. However, developing adsorbents which can efficiently distinguish CH4, C2H6, and C3H8 molecules remains challenging. We herein report an ultra-stable layered hydrogen-bonded framework (HOF-NBDA), which features differential affinities and adsorption capacities for CH4, C2H6, and C3H8 molecules, respectively. Breakthrough experiments on ternary component gas mixture show that HOF-NBDA can achieve efficient separation of CH4/C2H6/C3H8 (v/v/v, 85/7.5/7.5). More importantly, HOF-NBDA can realize efficient C3H8 recovery from ternary CH4/C2H6/C3H8 gas mixture. After one cycle of breakthrough, 70.9 L·kg-1 of high-purity (≥ 99.95%) CH4 and 54.2 L·kg-1 of C3H8 (purity ≥99.5%) could be obtained. Furthermore, excellent separation performance under different flow rates, temperatures, and humidities could endow HOF-NBDA an ideal adsorbent for the future natural gas purification.

Enhanced Ni(II) Removal from Wastewater Using Novel Molecular Sieve-Based Composites

This study focuses on the efficient removal of Ni(II) from spent lithium-ion batteries (LIBs) to support environmental conservation and sustainable resource management. A composite material, known as molecular sieve (MS)-based metal-organic framework (MOF) composites (MMCs), consisting of a synthesized MS matrix with integrated MOFs, was developed for the adsorption of Ni(II). The structural and performance characteristics of the MMCs were evaluated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and N2 adsorption-desorption isotherms (BET). Batch adsorption experiments were conducted to assess the Ni(II) adsorption performance of the MMCs. The results revealed that, under conditions of pH 8 and a temperature of 298 K, the MMCs achieved near-equilibrium Ni(II) adsorption within 6 h, with a maximum theoretical adsorption capacity of 204.1 mg/g. Further analysis of the adsorption data confirmed that the adsorption process followed a pseudo-second-order kinetic model and Langmuir isotherm model, indicating a spontaneous, endothermic chemical adsorption mechanism. Importantly, the MMCs exhibited superior Ni(II) adsorption compared to the MS. This study provides valuable insights into the effective recovery and recycling of Ni(II) from spent LIBs, emphasizing its significance for environmental sustainability and resource circularity.

Precise Control of Ultramicropores of Novel Carbons Molecule Sieves Derived from Coffee Bean for Efficient Sieving Propylene from Propane

The development of granular carbon materials with outstanding selectivity for the separation of alkenes and alkanes is highly desirable in the petrochemical industry but remains a significant challenge due to closely similar molecular sizes and physical properties of adsorbates. Herein, we report a facile approach of using natural biomass to prepare novel granular carbon molecule sieves with a molecular recognition accuracy of 0.44 Å and propose a new three-region model for the pore size distribution of amorphous porous carbons. Coffee bean-based granule carbon molecular sieves (CFGCs) were prepared with precise micropore regulation with subangstrom accuracy and characterized using molecular probes to reveal the evolution of carbon structure during preparation. The CFGC-0.09-750 demonstrates exceptional selectivity adsorption toward C3H6 while excluding C3H8, with an uptake ratio of 106.75 and a C3H6 uptake of 1.88 mmol/g at 298 K and 100 kPa, showcasing its immense potential in industrial applications for separating C3H6 and C3H8. The novel three-region model established in this work can clearly and reasonably elucidate why the samples CFGCs can screen propylene from propane at the subangstrom level. This study provides important guidance for the development of new carbon molecular sieves with subangstrom accuracy in molecular recognition and separation capacity.

Covalent organic frameworks (COFs): a promising CO2 capture candidate material

Covalent organic frameworks (COFs) are an emerging kind of porous crystal material.

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

Rapid and highly efficient C₃H₆/C₃H₈ separation over porous carbons is seriously hindered by the trade-off effect between adsorption capacity and selectivity. Here, we report a new type of porous carbon nanoplate (CNP) featuring an ultrathin thickness of around 8 nm and easily accessible ultramicropores (approximately 5.0 Å). The ultrathin nature of the material allows a high accessibility of gas molecules into the interior transport channels, and ultramicropores magnify the difference in diffusion behavior between C₃H₆ and C₃H₈ molecules, together ensuring a remarkable C₃H₆/C₃H₈ separation performance. The CNPs show a high and steady C₃H₆ capacity of up to 3.03 mmol g^-1 at 298 K during consecutive dynamic cycles, which is superior to that of the state-of-the-art porous carbons and even porous crystalline materials. In particular, the CNPs show a rapid gas diffusivity, which is 1000 times higher than that of conventional activated carbons. This research provides a promising design principle for addressing the selectivity-capacity trade-off for other types of adsorbent materials.