The_Catalyst_Review_December_2023 - 17

Figure 1a illustrates the synthesis of two carborane-based COFs via the combination of linear diformyl-p-carborane (DFCB) with
1,3,5,7-tetraaminoadamantane (TAA) and tetrahedral tetra(4-aminophenyl) methane (TAPM). Following extensive analytical analysis,
these workers carried out an evaluation of the adsorption capability of TAPM-DFCB-COF and TAA-DFCB-COF toward hexane
isomers (Figure 2) where it was shown that TAPM-DFCB-COF and TAA-DFCB-COF exhibited varied adsorption capability toward the
five hexane isomers with the adsorption capacities of these isomers decreasing with the increase in their degree of branching.
Figure 2. Single-component adsorption isotherms of (a) TAA-DFCB-COF and (b) TAPM-DFCB-COF toward nHEX (black curve), 2MP (red
curve), 3MP (blue curve), 23DMB (orange curve), and 22DMB (green curve) at 298 K. Column breakthrough curves for the quinary mixture
of nHEX (black curve), 2MP (red curve), 3MP (blue curve), 23DMB (orange curve), and 22DMB (green curve) using (c) TAA-DFCB-COF and (d)
TAPM-DFCB-COF as solid porous packing and the calculated RON values for the eluted mixture (black curve). B−Hδ−···Hδ +−C dihydrogen
and C−H···π interactions between TAPM-DFCB-COF and (e) nHEX, (f) 2MP, (g) 3MP, (h) 23DMB, and (i) 22DMB estimated using density
functional theory calculations.
Linear nHEX can be easily adsorbed to saturation at low pressure. In contrast, higher pressure is required to implement the
saturation adsorption of monobranched and dibranched isomers adsorption capability of TAPM-DFCB-COF and TAA-DFCBCOF
toward hexane isomers. The high uptake amounts of TAPM-DFCB-COF can be attributed to high pore volume, appropriate
pore size, and high-density Bδ+
interactions and implement the encapsulation of hexane molecules. Although TAA-DFCB-COF is abundant in Bδ+
−Hδ− sites anchored on the pore surfaces, which can interact with C−H bonds through dihydrogen
sites, the
−Hδ−
pore volume and size are considerably smaller than those of TAPM-DFCB-COF, thus leading to lower capacities for these isomers.
However, TAA-DFCB-COF exhibited a much higher uptake selectivity of nHEX over the monobranched and dibranched isomers.
Xiaoyi X, Qirui C, Hongzheng C, et al. (2023) J. Am. Chem. Soc., https://doi.org/10.1021/jacs.3c08541
CO2 Capture and Direct Air CO2
by Metal Hydroxides and a Ru/Al2
Capture Followed by Integrated Conversion to Methane Assisted
Catalyst
O3
Although CO2 is currently considered a significant contributor to global warming, it also serves as a critical building block and
generated via an energetic, wasteful capture and release
feedstock to produce numerous chemicals and fuels. For example, it can undergo hydrogenation via the Sabatier process to
produce methane. However, this reaction requires high-purity CO2
process. Efforts are therefore underway to develop a Sabatier-type process using CO2
as a source of methane.
adducts obtained through capture from
O3 catalyst. Moreover, the process can be
various sources to bypass the energy-intensive CO2 desorption step. Herein, the authors report the conversion of several alkali
and alkaline earth metal carbonate salts to methane utilizing a commercial 5%Ru/Al2
extended to include air capture of CO2
The Catalyst Review
December 2023
17
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