Light Hydrocarbon Separations Using Porous Organic Framework Materials

Abstract

Light hydrocarbons (C1–C3) are used as basic energy feedstocks and as commodity organic compounds for the production of many industrially necessary chemicals. Due to the nature of the raw materials and production processes, light hydrocarbons are generated as mixtures, but the high‐purity single‐component products are of vital importance to the petrochemical industry. Consequently, the separation of these C1–C3 products is a crucial industrial procedure that comprises a significant share of the total global energy consumption per year. As a complement to traditional separation methods (distillation, partial hydrogenation, etc.), adsorptive separations using porous solids have received widespread attention due to their lower energy costs and higher efficiency. Extensive research has been devoted to the use of porous materials such as zeolites and metal‐organic frameworks (MOFs) as solid adsorbents for these key separations, owing to the high porosity, tunable pore structures, and unsaturated metal sites present in these materials. Recently, porous organic framework (POF) materials composed of organic building blocks linked by covalent bonds have also shown excellent properties in light hydrocarbon adsorption and separation, sparking interest in the use of these materials as adsorbents in separation processes. This Minireview summarizes the recent advances in the use of POFs for light hydrocarbon separations, including the separation of mixtures of methane/ethane, methane/propane, ethylene/ethane, acetylene/ethylene, and propylene/propane, while highlighting the relationships between the structural features of these materials and their separation performances. Finally, the difficulties, challenges, and opportunities associated with leveraging POFs for light hydrocarbon separations are discussed to conclude the review.

Separation and Purification of Hydrocarbons with Porous Materials

“…Owing to the tremendous prospects of adsorptive separation technology, a vast variety of porous materials have been explored for the separation and purification of hydrocarbon mixtures. Porous materials, such as activated carbons, carbon molecular sieves, zeolites, activated aluminas, silica gels, polymer resins, metal–organic frameworks (MOFs), metal organic cages, and porous organic frameworks (POFs), have been extensively studied for adsorptive separations [3c, 11] . Porous carbons have been among the most investigated porous adsorbents with low cost, high specific surface areas, and high stability.…”

“…POFs assembled from organic building blocks via strong covalent bonds can be divided into two subcategories: crystalline, including covalent organic frameworks (COFs), and amorphous, like conjugated microporous polymers (CMPs) and hypercrosslinked polymers (HCPs), porous organic cages (POCs), covalent triazine frameworks (CTFs), and porous aromatic frameworks (PAFs). With high stability, porosity, and designable structures, POFs have exhibited great potential for gas separation processes [3c] …”

Facile synthesis of highly porous hyper‐cross‐linked polymer for light hydrocarbon separation

“…[ 33 ] HCPs have demonstrated considerable potentials in gas separation, especially in separation of light hydrocarbons such as methane (CH 4 ), ethane (C 2 H 6 ), ethylene (C 2 H 4 ), and acetylene (C 2 H 2 ). [ 34 ] In 2013, Zhu and his colleagues constructed a microporous borate ester‐based COF by holding together tetra (4‐dihydroxyborylphenyl) methane and 1,2,4,5‐tetrahydroxybenzene. [ 35 ] Benefiting from its microporous texture, the resulting MCOF‐1 shows good potential in C 2 H 6 /CH 4 selectivity with a value of exceeding 80 at 298 K and 100 kPa, however, the borate ester‐based COF material is often unstable, which makes it not available in such separation under harsh conditions.…”

Gas Adsorption in Amorphous Porous Boron Oxynitride: Grand Canonical Monte Carlo Simulations and Experimental Determination

“…Tackling these challenges calls for the development of porous materials, exhibiting robustness and tunable physical-chemical properties, to facilitate separations at the micro-and mesoscale. For these purposes, a wide platform of porous materials are currently under research, which include metal-organic frameworks (MOFs), [2][3][4] covalent-organic frameworks (COFs), [5][6][7] activated carbon, [8][9][10] porous organic polymers, [11][12][13] and inorganic compounds such as zeolites. [14][15][16] These materials have been employed across a range of applications, such as gas storage, [17][18][19][20] , drug delivery, [21][22][23][24] water treatment, 25 CO2 capture, [26][27][28][29] and catalysis.…”