A Review on Robustness of Covalent Organic Polymers for CO₂ Capture

Abstract

The presence of carbon dioxide (CO2) in natural gas stream is a critical problem; besides causing corrosion it also reduces the energy contents and heating value of natural gas. Various separation techniques are available to separate CO2from natural gas, such as metal organic framework (MOF), covalent organic framework (COF) and Covalent Organic Polymer (COP) adsorbents. The criteria of adsorbent selection that need to be fulfilled include high adsorption capacity, high selectivity of CO2and hydrothermal stability at operating conditions. COPs are crystalline porous materials having high CO2capacity and selectivity in the presence of water vapors. However, the research on COP material development is new and scarce information is available in literature. In this prospect, the paper highlights the different types of COPs, their basic constituents and the adsorption capacities.

Countercation Effect on CO2 Binding to Oxo Titanate with Bulky Anilide Ligands

“…Deprotonation of the formatea nd con-comitantc leavageo fc arbon monoxide give the oxo complexes. [ 3 ] + fragment. This aryl ring-alkali metal cation interaction is ac ommons tructuralm otif for anionic transition metal tris(anilide) complexes with basic terminal ligands.…”

“…The normalc ovalent MgÀOs ingle bond (1.905(2) )i ndicatesastrong oxo-cation interaction in [(thf) 2 MgMe][1] (Figure 4, left). [22] The TiÀO( 1.724(2) )i sc omparable to its congener in [(Et 2 O) 2 Li][1]( 1.717 (2) ), which indicates an affini-ty to bind CO 2 .F or am ethyl-free magnesium-oxo species, the methyl group was abstracted with B(C 6 F 5 ) 3 .This triggered adisproportionationr eactionr esulting in the formation of [Mg(thf) 6 ][MeB(C 6 F 5 ) 3 ] 2 (Scheme S1, Supporting Information) and an ew magnesium-oxo species" [Mg][1] 2 ". [23] The bis(oxo) magnesiums pecies " [ 2 Mg][1] 2 ,m agnesium is coordinated in ad isphenoidal fashion by two oxo ligandsa nd two diethyle ther molecules (Figure 4, right).…”

“…Most recent efforts to bind carbon dioxide for sequestration purposes have focused on metal‐organic frameworks (MOFs) because of their potential to offer energy efficient recovery of the capture material . Another class of materials that are of interest in this application are covalent organic frameworks (COFs) and polymers (COPs) . These are stable in water and are more easily regenerated than MOFs.…”

“…[2] Another class of materialst hat are of interest in this application are covalent organic frameworks (COFs) and polymers (COPs). [3] These are stable in water and are more easily regenerated than MOFs. COPs and COFs for carbonc apture have amine sites that bind carbon dioxide reversibly.I n addition, the most common carbon sequestration systems use amine scrubbing with primary,s econdary and tertiary amines, but the products are difficult to reactivate.…”

“…[4] Another absorption method that has receivedc onsiderable attention is the reversible uptakeo fC O 2 at Lewis basic metal oxide surfaces. [5] In our group, we have previously investigated carbond ioxide uptake using the molybdate anion [6] and have reported on the reversible formation of carbonate from the binding of carbon dioxide to anionic titanium tris(anilide) complexesw ith at erminal oxo ligand, [7] [OTi(N[ t Bu]Ar) 3 ] À with Ar = 3,5-Me 2 C 6 H 3 .T his system might serve as ac atalyst for the chemicalf ixation of carbon dioxide in solution, if bound CO 2 can be transferredt op rimary bis(amines) [8] and ortho-aminobenzonitriles [9] as has been demonstrated with ab asic tungstate catalyst.R elateda nionict erminal oxo complexes of zirconium and their reactivity with CO 2 to form carbonatec omplexesh ave recently been investigated in detail by Thomas and co-workers. [10] Organoantimony and organobismuth complexesa re catalysts for the chemical fixationo fC O 2 to cyclic carbonates.…”