Adamantane-Based Micro- and Ultra-Microporous Frameworks for Efficient Small Gas and Toxic Organic Vapor Adsorption

Abstract

Microporous organic polymers and related porous materials have been applied in a wide range of practical applications such as adsorption, catalysis, adsorption, and sensing fields. However, some limitations, like wide pore size distribution, may limit their further applications, especially for adsorption. Here, micro- and ultra-microporous frameworks (HBPBA-D and TBBPA-D) were designed and synthesized via Sonogashira–Hagihara coupling of six/eight-arm bromophenyl adamantane-based “knots” and alkynes-type “rod” monomers. The BET surface area and pore size distribution of these frameworks were in the region of 395–488 m2 g−1, 0.9–1.1 and 0.42 nm, respectively. The as-made prepared frameworks also showed good chemical ability and high thermal stability up to 350 °C, and at 800 °C only 30% mass loss was observed. Their adsorption capacities for small gas molecules such as CO2 and CH4 was 8.9–9.0 wt % and 1.43–1.63 wt % at 273 K/1 bar, and for the toxic organic vapors n-hexane and benzene, 104–172 mg g−1 and 144–272 mg g−1 at 298 K/0.8 bar, respectively. These are comparable to many porous polymers with higher BET specific surface areas or after functionalization. These properties make the resulting frameworks efficient absorbent alternatives for small gas or toxic vapor capture, especially in harsh environments.

Exceptionally Stable Microporous Organic Frameworks with Rigid Building Units for Efficient Small Gas Adsorption and Separation

“…Typically, MPOF-Ad-1 displays the highest CO 2 uptake capacity, up to 69.5 cm 3 g –1 (13.9 wt %) at 273 K/1.0 bar and 44.3 cm 3 g –1 (8.8 wt %) at 298 K/1.0 bar. The CO 2 uptake capacity of these MPOF-Ads networks are comparable to many microporous organic frameworks reported in the literature, such as CMOPs (36.5–41.2 cm 3 g –1 ), HBPBBA-D, and TBBPA-D (45.5 and 45.1 cm 3 g –1 ) . Though, they are lower than some of those with numerous heteroatoms, such as HCMs (115.7–158.0 cm 3 g –1 ), P-PCz (124.0 cm 3 g –1 ), PDA 0.3 /MA 0.7 -2 (102.4 cm 3 g –1 ), and TrzPOPs (137.8–190.1 cm 3 g –1 ) (Table S5, Supporting Information).…”

“…Figure S18 (Supporting Information) illustrates the dependencies of gas uptake capacity of MPOF-Ads on the T c of three gases (304.2, 190.6, and 126.2 K, for CO 2 , CH 4 , and N 2 , respectively) . The fact that the selectivity of CO 2 /CH 4 is apparently lower than that of CO 2 /N 2 (Table ) might be explained by considering the differences in the gas T c and kinetic diameter (3.80 Å for CH 4 and 3.64 Å for N 2 ) . Compared to CH 4 , N 2 has a smaller molecular size and lower T c indicating a lower adsorption capacity (Figure S18, Supporting Information); therefore, the MPOF-Ads adsorbents demonstrate a higher selectivity of CO 2 /N 2 than CO 2 /CH 4 .…”

“…Application of the Brunauer−Emmett−Teller (BET) model to the N 2 adsorption isotherms yielded specific surface areas of 734.1, 737.3, and 437.5 m 2 g −1 and corresponding Langmuir surface areas of 1011.5, 1007.1, and 593.3 m 2 g −1 for the MPOF-Ad-1, MPOF-Ad-2, and MPOF-Ad-3 materials, respectively (Table 1). The lower value for MPOF-Ad-3 could be a result of its cross-linking density, 28 that is, the lower the density the lower the surface area. SEM micrographs (Figure 4a) revealed that these MPOF-Ads networks are composed of loose and agglomerated microparticles with a spherical granular shape with some surface roughness, and that the MPOF-Ad-1 and MPOF-Ad-2 materials are more agglomerated than MPOF-Ad-3.…”

Multifunctional Polyhedral Oligomeric Silsesquioxane (POSS) Based Hybrid Porous Materials for CO2 Uptake and Iodine Adsorption

“…The synthesis of POPs was successfully achieved using various synthetic methods, including Friedel–Crafts arylation, Schiff base reactions, Suzuki reactions, Yamamoto reactions, Heck reactions, and Sonogashira reactions [ 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ]. In addition, POPs can be classified into different kinds of materials, such as covalent organic frameworks (COFs), conjugated microporous polymers (CMPs), hypercrosslinked polymers (HCPs), covalent triazine-based frameworks (CTFs), metal–organic frameworks (MOFs), and polymers of intrinsic microporosity (PIMs) [ 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 ].…”

Multifunctional Hypercrosslinked Porous Organic Polymers Based on Tetraphenylethene and Triphenylamine Derivatives for High-Performance Dye Adsorption and Supercapacitor

“…Microporous organic polymers (MOPs) have attracted much attention as next-generation materials in the industry and academic areas because of their good thermal stability, low density, low regeneration energy, high pore volume and large BET (Brunauer–Emmett–Teller) surface area, synthetic diversity, and easier preparation [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. MOPs have been used in many potential applications, such as water treatment, drug delivery, chemical sensing, heterogeneous catalysis, energy storage, hydrogen evolution, nanofiltration, oil scavenging, carbon dioxide reduction, gas separation and gas storage [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. There are different kinds of MOPs, such as conjugated microporous polymers (CMPs) [ 15 , 16 , 17 , 18 ], covalent organic frameworks (COFs) [ 16 , 17 , 18 , 19 , 20 ], polymers of intrinsic microporosity (PIMs) [ 21 , 22 , 23 ], covalent triazine-based frameworks (CTFs) [ 24 , 25 , 26 , 27 , 28 ], and hypercrosslinked polymers (HCPs) [ 29 , 30 , 31 , 32 ].…”