CO2 Sorption Research Articles

A green approach towards sorption of CO2 on waste derived biochar

Carbon capture technologies have advanced in recent years to meet the ever-increasing quest to minimize excessive anthropogenic CO2 emissions. The most promising option for CO2 control has been identified as carbon capture and storage. Among the numerous sorbents, char generated from biomass thermal conversion has shown to be an efficient CO2 adsorbent. This study examines various characteristics that can be used to increase the yield of biochar suited for carbon sequestration. This review gives recent research progress in the area, stressing the variations and consequences of various preparation processes on textural features such as surface area, pore size and sorption performance with respect to CO2's sorption capacity. The adjoining gaps discovered in this field have also been highlighted herewith, which will serve as future work possibility. It aims to analyse and describe the possibilities and potential of employing pristine and modified biochar as a medium of CO2 capture. It also examines the parameters that influence biochar's CO2 adsorption ability and pertinent challenges regarding the production of biochar-based CO2 sorbent materials.

Unravelling gas sorption in the aluminum metal‐organic framework CAU‐23: CO2, H2, CH4, SO2 sorption isotherms, enthalpy of adsorption and mixed‐adsorptive calculations

AbstractThe report is the first broader evaluation of the gas sorption properties of CAU‐23 for the adsorptives CO2, H2, CH4, and SO2. CAU‐23 is of intermediate porosity among Al‐MOFs with specific BET surface areas of the order of MIL‐100>MIL‐53>CAU‐23>MIL‐160>MIL‐53‐TDC>Alfum>CAU‐10‐H and total pore volumes of the order of MIL‐100>MIL‐53>CAU‐23>Alfum=MIL‐160>MIL‐53‐TDC>CAU‐10‐H. CO2 uptake (3.97 mmol g−1, 293 K) and H2 uptake (10.25 mmol g−1, 77 K) of CAU‐23 are second in the series and only slightly smaller than for MIL‐160. The CH4 uptake of CAU‐23 (0.89 mmol g−1, 293 K) is unremarkable in comparison with the other Al‐MOFs. The SO2 uptake (8.4 mmol g−1, 293 K) follows the porosity and higher SO2 uptakes were only observed for MIL‐53 and MIL‐100. CAU‐23 is one of the best Al‐MOFs for high‐pressure sorption of CO2, with an uptake of 33 wt.‐% at 20 bar, 293 K. Gas sorption measurements at two different temperatures gave near zero‐coverage enthalpy of adsorptions, ▵Hads0 for CO2 of −22 kJ mol−1 and of SO2 for −38 kJ mol−1 which is at the low end of the other Al‐MOFs (−22 to −39 kJ mol−1 for CO2; −41 to −51 kJ mol−1 for SO2), yet ▵Hads increases for CAU‐23 with CO2 and SO2 to −25 and −57 kJ mol−1, respectively. For CO2/CH4 and SO2/CO2 separation, ideal adsorbed solution theory (IAST) predicted gas selectivities of 5 and 27–50 (depending on molar ratio and model), respectively, in line with 4.5–6.3 and 17–50, respectively, with most of the other Al‐MOFs, where only MIL‐53‐TDC with 83 and MIL‐160 with 126 gave a higher SO2/CO2 selectivity at a molar ratio of 0.5.

Calorimetric study of the CO2 gate sorption of elastic layer-structured metal–organic frameworks (ELM-11 and ELM-12)

Elastic layer-structured metal–organic frameworks (ELMs) have flexible structures. ELM-11 shows the gate phenomenon on CO2 sorption–desorption, and ELM-12 shows the double-step sorption of N2 at 77 K, but the CO2 sorption of ELM-12 has not been investigated in detail. Calorimetric measurements of the heats of sorption and desorption enable analysis of the sorption mechanism and behavior. The heats of sorption, desorption, and the gate phenomenon for ELM-11 and -12 were obtained calorimetrically and compared with those obtained using the van 't Hoff and Clausius–Clapeyron equations. The sorption heat was greater than that of CO2 liquefaction, despite the destabilization of the ELM resulting from interlayer expansion. Further, the heat was similar to that evaluated using van 't Hoff plots. The rapid uptake and fast rate of CO2 sorption resulting from the gate phenomenon yielded an energetically favorable process and more effective heat exchange than those of existing adsorbents, which show modest adsorption rates. Therefore, ELM-11 has applications in heat management for gas sorption. Unlike ELM-11, ELM-12 did not show gated CO2 sorption below 760 Torr but, instead, the open micropores were filled. In addition, the heat of adsorption was higher than that of the sublimation of CO2.

Thermochemical study of CO2 capture by mesoporous silica gel loaded with the amino acid ionic liquid 1-ethyl-3-methylimidazolium glycinate

A series of composite CO2 sorbents were obtained by placing an amino acid ionic liquid (AAIL) 1-Ethyl-3-methylimidazolium glycine ([Emim][Gly]) into mesoporous silica gel using an impregnation method. The parameters of the porous structure for the silica support and composite sorbents were determined from nitrogen adsorption-desorption isotherms measured at 77 K. The morphology of the materials was studied using field-emission scanning electron microscopy. It was shown that at lower [Emim][Gly] loadings (<50 wt%), the sorption is fast and the dynamic CO2 sorption capacity of the material is proportional to the mass content of the AAIL. At higher [Emim][Gly] loadings (≥50 wt%), the rate of CO2 sorption by the AAIL decreases due to hindered mass transfer. An increase in CO2 concentration in the gas flow leads to a faster sorption and higher CO2 sorption capacity for the AAIL-containing composite. Meanwhile, the integral enthalpy of sorption decreases with increasing CO2 concentration, which can be explained by the greater contribution of physical adsorption/absorption processes to the total CO2 sorption capacity at higher CO2 concentrations. The most promising composite material (40 wt% [Emim][Gly]/SiO2) was tested in consecutive temperature-swing sorption-desorption cycles. It was demonstrated that lowering the regeneration temperature from 100 to 80 °C leads to a decrease in the dynamic sorption capacity of the material, but ensures its stability in the cyclic sorption-desorption process.

Thermodynamic and kinetic properties of Li3BO3 modified by the alkali fluorides addition in the CO2 capture process

Tri-lithium borate (Li3BO3) is a high-capacity CO2 sorbent recently proposed for the intermediate temperature range of 500 °C to 650 °C. Up to date, only a study of CO2 sorption kinetic behavior of Li3BO3 modified by nitrite salts has been carried out. The equilibrium properties that relate the dependence of the partial pressure of CO2 and temperature are also unknown. In this work, a novel two-step mechano-thermal method was optimized to produce both pure and modified Li3BO3 by addition of 0.1 mol of Na- and K-fluorides. Fast reaction by milling of Li2CO3 and H3BO3 forms the intermediate LiB5O8·5H2O compound at room temperature, which transforms to Li3BO3 as single phase by heating at 600 °C. Pressure-composition isotherms allow to determine the existence of two plateaus, each of them ascribed to different phases: Li6B4O9 at low CO2 partial pressure (ΔH = 58 ± 5 kJ/mol) and LiBO2 at high CO2 partial pressure (ΔH = 106 ± 6 kJ/mol). The mathematical expression that relates the equilibrium CO2 absorption partial pressure and the temperature of modified and unmodified Li3BO3 was reported. Na- and K-modified Li3BO3 show remarkably fast kinetics with high CO2 capture capacity (e.g. greater than 45 wt% at 500 °C) and excellent regenerability, with minor deterioration in performance over 30 cycles of CO2 sorption. The kinetic behavior of modified Li3BO3 by alkali fluorides is enhanced by the formation of an eutectic melt phase during carbonation, as confirmed by differential scanning calorimetry and the simultaneous detection of LiF. In addition, alkali fluorides could generate oxygen vacancies and modify the surface composition by enrichment of Li-O sites, also favoring the CO2 sorption kinetics.

Carbon Dioxide Chemisorption by Ammonium and Phosphonium Ionic Liquids: Quantum Chemistry Calculations.

Carbon capture and storage is an important technological endeavor aiming to improve the ecology by combating global warming. The present work investigates reaction paths that are responsible for CO2 chemisorption by the ammonium- and phosphonium-based ionic liquids containing an aprotic heterocyclic anion 2-cyanopyrrolide. We exemplify that 2 mol of CO2 per 1 mol of the gas scavenger can be theoretically fixed by such ionic liquids. Both the cation and anion participate in the chemisorption. The corresponding standard enthalpies and potential energies are moderately negative. The chemisorption reaction, as revealed by the simulations of competing pathways, is started by the donation of the proton from the cation to the anion. The double covalent bond in the cation's structure emerges. The barriers to all reactions involving the phosphonium-based cation are relatively small and favor practical applications of the considered sorbents. The performance of the ammonium-based cation is less favorable due to the inherent instability of the tetraalkylammonium ylide. The role of phosphonium ylide in the mechanism of the reaction is carefully characterized. The performance of the aprotic anion as a CO2 scavenger is unaffected by the chemical identity of the counterion. The essential heights of the identified steric barriers underline the necessity to simulate the entire structures of the reacting species to obtain a reliable description of chemisorption. The reported results foster a fundamental understanding of the outstanding CO2 sorption performance of the quaternary ammonium- and phosphonium-based 2-cyanopyrrolides.

CO2 Capture over Activated Carbon Derived from Pulverized Semi-Coke

Pulverized semi-coke was employed as raw material to prepare activated carbon via steam activation and evaluated as a CO2 adsorbent. The effects of the preparation parameters including demineralization, activation temperature, activation time and steam flow on the structure and performance of the synthesized activated carbon were investigated. It was found that the microporous structure of activated carbon was greatly influenced by demineralization order and activation conditions. Demineralization before activation significantly increased the microporous structure of the activated carbon, which was ascribed to the removal of the inorganic fraction. Compared to the commercial activated carbon, activated carbon obtained by employing 150 mL/min steam to treat the demineralized pulverized semi-coke at 700 °C for 70 min possessed a higher CO2/N2 selectivity of 34.4 and good cyclic performance, which was due to its narrow microporosity of 0.55 nm. Furthermore, it was proved that a pore size of smaller than 1 nm is favorable for CO2 sorption.

High-pressure carbon dioxide solubility in terpene based deep eutectic solvents

This work investigates carbon dioxide solubility in four type V natural deep eutectic solvents (NADES). The studied solvents have hydrophobic nature, and they were prepared by using carvone (CAR), cineole (CIN), thymol (THY), and menthol (MEN). Solubilities of carbon dioxide (CO2) have been determined via new apparatus that uses the isochoric saturation method. The apparatus has been validated against a widely used calibration fluid, which was selected as choline chloride (ChCl) and urea system, a.k.a. reline. The NADES have been tested at 25 °C and 35 °C isotherms and pressures up to 40 bars. Material characterization, including Fourier transform infrared (FTIR) and thermal gravimetric analysis (TGA), have been obtained and presented. The experimental heat of absorption of CO2 presented as a function of pressure, and the CO2 sorption kinetics presented based on the fractional amount of absorbed CO2 versus time. The results demonstrated that the solubility of CO2 in monoterpenoid-based hydrophobic NADES increased with increasing pressure and decreasing temperature. In addition to their hydrophobic nature, high CO2 sorption performance with rapid CO2 solubility rate make NADES good candidates for future carbon management applications.

Selective and Multicyclic CO2 Adsorption with Visible Light-Driven Photodegradation of Organic Dyes in a Robust Metal-Organic Framework Embracing Heteroatom-Affixed Pores.

Pore environment modulation with polarizing groups is one of the essential prerequisites for selective carbon dioxide (CO2) adsorption in metal-organic frameworks (MOFs), wherein judicious installation of the photocatalytic feature can promise visible light-triggered degradation of toxic organic dye molecules. However, astute amalgamation of both these attributes over a single MOF is rather rare, yet much anticipated in view of sustainable applications. Pore engineering is effectively harnessed in a Zn(II)-based three-dimensional (3D) MOF, CSMCRI-16 (CSMCRI = Central Salt and Marine Chemicals Research Institute), through mixed-ligand assembly of a N-rich linker (L), 4,4'-oxybis(benzoic acid) (H2oba) ligand, and [Zn2(CO2)4N2] paddle-wheel secondary building units (SBUs). The noninterpenetrated structure contains unbound nitrogen and accessible oxygen atom-decorated porous channels and exhibits admirable stability in diverse organic solvents, open air, and at elevated temperatures. The heteroatom-decorated porous channels facilitated excellent CO2 uptake in the activated MOF (16a) with high selectivity over N2 (CO2/N2: 155.3) at 273 K. The framework further exhibits reasonable CO2 affinity and multicyclic CO2 sorption recurrence without a significant loss in the uptake capacity. Benefitting from the presence of the [Zn2(CO2)4N2] cluster in conjugation with π-conjugated organic ligands, the extended 3D network revealed an optical band gap energy of 2.55 eV, which makes the MOF an efficient photocatalyst toward the degradation of the cationic dyes crystal violet (CV) and methylene blue (MB) in the presence of a simple 40 W visible light lamp without any assistance of external oxidants. The catalyst exhibits multicyclic performance and short reaction time in addition to the fact that catalytic efficiencies (CV: 97.2%, MB: 97.8%) are comparable to those of contemporary materials.

From biopolymer dissolution to CO2 capture under atmospheric pressure - A molecular view on biopolymer@Ionic liquid materials

Finding a cheap and easily recycling material that can capture CO2 under atmospheric pressure (1 atm) is of paramount importance. In this context, combining ionic liquids (ILs) with abundant and natural materials, such as chitin-based biopolymers, appears as an interesting alternative. In this work, four acetate-based ILs were selected to explore the solubility of chitin, chitosan, and carboxymethyl-chitosan. Using carboxymethyl-chitosan and biopolymer monomer units as models, different Nuclear Magnetic Resonance (NMR) techniques, namely, 1H, 13C, nuclear Overhauser effect spectroscopy, and spin-lattice relaxation, were performed to evaluate the dissolution. Shrimp shells were used as a chitin source. Through a simple acid/base treatment, it was possible to remove minerals and proteins, and use it to prepare biopolymer@IL materials for CO2 capture tests. Efficient CO2 sorption capacity was observed upon bubbling CO2 with a maximum of 2.32 mmolCO2/gsorbent. Under N2 bubbling, the system demonstrated excellent recycling capacity using a room temperature procedure that outperformed aqueous amine solutions recycling. The absence of heating and vacuum recycling procedures, combined with the use of N2 or compressed air is much more appealing for industrial applications.

Dependence of the foaming window of poly(ethylene terephthalate-co-ethylene 2,5-furandicarboxylate) copolyesters on FDCA content

The objective of the present work was to study the dependence of the foaming temperature window of poly(ethylene terephthalate-co-ethylene 2,5-furandicarboxylate) (PEFT) copolyesters on 2,5-furandicarboxylic acid (FDCA) content after different saturation pressures. First, the chemical structure of PEFT copolyesters was characterized, and the effect of FDCA content on the sorption of carbon dioxide (CO2) and the crystallization behavior of PEFT copolyesters was studied. Second, the foaming of PEFT copolyesters was carried out using a batch foaming process. Third, the foaming temperature window was defined for PEFT copolyesters through identifying the lower and the upper foaming temperature boundaries. It was found that with the increase of FDCA content, the sorption of CO2 decreased, and the melting temperature and the crystallinity of PEFT decreased. This led to the increase of the lower foaming temperature while the decrease of the upper one, thus making the foaming temperature window gradually narrowed. It is considered that the lower foaming temperature was determined by the rigidity of the macromolecular chains as well as the CO2 sorption, while the upper one by the crystals formed in PEFT with copolymerization of FDCA units. In addition, with the increase of the saturation pressure, the lower foaming temperature of all PEFT samples decreased, and the upper foaming temperature of PEFT15%, PEFT20% and PEFT30% decreased as well, attributed to the plasticization effect of CO2. However, the upper foaming temperature of PET, PEFT5% and PEFT10% unexpectedly increased with the saturation pressure due to the CO2-induced crystallization. The findings in this study are very important for guiding the foaming and cell structure control, not only for PEFT copolyesters, but also for other semicrystalline copolymers.

Fabrication of nitrogen-doped graphene quantum dots hybrid membranes and its sorption for Cu(II), Co(II) and Pb(II) in mixed polymetallic solution

With the rapid development of new–energy batteries, heavy-metals pollution from spent batteries has drawn much attention. Various techniques are recently proposed to delete or eliminate such pollution. Among which, membrane sorption exhibits exceptional advantages for the separation of multi-metal solution. For such a purpose, nitrogen-doped graphene quantum dots (N-GQDs) hybrid membranes were fabricated via sol–gel technique and hydrothermal synthesis, in which the precursor powder of N-GQDs was obtained by the combination of urea (used as a nitrogen source) and citric acid (used as a carbon source). Subsequently, the N-GQDs precursor was mixed with silane and PVA to generate N-GQDs hybrid membranes (NHMs). Competitive sorption of Cu(II), Co(II) and Pb(II) in the mixed polymetallic solution, such as a mixed Cu(II), Co(II) and Pb(II) ternary solution, a mixed Cu(II), Pb(II), Ca(II), Co(II) and Cr(III) quintuple solution, was investigated. It indicated that Cu(II) sorption on NHMs had better selectivity in these mixed polymetallic solutions. Moreover, sorption mechanism of Cu(II), Co(II) and Pb(II) demonstrates that the sorption of NHMs for Cu(II) and Pb(II) abided by Elovich model, indicating the properties of heterogeneous chemisorption. Such a trend shows that the sorption via chemical process between the active sites on the top-layer of NHMs, and Cu(II) and Pb(II) is one of the dominant interfering factors. Desorption testing demonstrated that EDTA-2Na is a best de-sorbent for Cu(II) sorption on NHMs and the number of cycles of these membranes can reach up to 10 times. These findings suggest that NHMs can be used to adsorb Cu(II), Co(II) and Pb(II) from mixed polymetallic solution, indicating promising applications in the successive separation of wastewater containing multiple mixed toxic metals from spent new-energy batteries and other metal-containing wastewater.

Study of CO2 and N2 sorption into ZIF-8 at high pressure and different temperatures

Worldwide consumption of natural gas (NG) has increased in recent years due to newly discovered reserves and greater energy demand. However, the oil and gas industry has encountered significant challenges regarding the capacity to store and process NG to remove impurities, mainly CO2, in order to avoid corrosion and gas hydrate formation. Thus, it is necessary to optimize the separation process in high-pressure adsorption columns by choosing more selective adsorbents with both high chemical and mechanical stabilities. To make this possible, metal-organic frameworks (MOFs) arise as potential materials due to their high surface area and selectivity. However, there must be a better understanding of the physicochemical stability of these materials under high pressure in relation to structural, thermal, and chemical changes. In this sense, this study evaluates the stability of MOF (ZIF-8) using CO2 and N2 as the sorption gas in a high-pressure equilibrium cell. The X-ray diffraction data show that all ZIF-8 samples are highly crystalline. The samples treated at 20 ​°C show insignificant surface area changes, while an expressive reduction in these areas occurs when treated at 60 ​°C. All samples showed thermal stability under high pressure. Fourier transform infrared spectroscopy, and scanning electron microscopy analyses showed no chemical and morphological changes in the ZIF-8 before and after being submitted to CO2 and N2 sorption at high pressure.

Understanding the Impacts of Support-Polymer Interactions on the Dynamics of Poly(ethyleneimine) Confined in Mesoporous SBA-15.

Supported amines are a promising class of CO2 sorbents offering large uptake capacities and fast uptake rates. Among supported amines, poly(ethyleneimine) (PEI) physically impregnated in the mesopores of SBA-15 silica is widely used. Within these composite materials, the chain dynamics and morphologies of PEI strongly influence the CO2 capture performance, yet little is known about chain and macromolecule mobility in confined pores. Here, we probe the impact of the support-PEI interactions on the dynamics and structures of PEI at the support interface and the corresponding impact on CO2 uptake performance, which yields critical structure-property relationships. The pore walls of the support are grafted with organosilanes with different chemical end groups to differentiate interaction modes (spanning from strong attraction to repulsion) between the pore surface and PEI. Combinations of techniques, such as quasi-elastic neutron scattering (QENS), 1H T1-T2 relaxation correlation solid-state NMR, and molecular dynamics (MD) simulations, are used to comprehensively assess the physical properties of confined PEI. We hypothesized that PEI would have faster dynamics when subjected to less attractive or repulsive interactions. However, we discover that complex interfacial interactions resulted in complex structure-property relationships. Indeed, both the chain conformation of the surface-grafted chains and of the PEI around the surface influenced the chain mobility and CO2 uptake performance. By coupling knowledge of the dynamics and distributions of PEI with CO2 sorption performance and other characteristics, we determine that the macroscopic structures of the hybrid materials dictate the first rapid CO2 uptake, and the rate of CO2 sorption during the subsequent gradual uptake stage is determined by PEI chain motions that promote diffusive jumps of CO2 through PEI-packed domains.

Long-term performance of highly selective carbon hollow fiber membranes for biogas upgrading in the presence of H2S and water vapor

Biogas is an increasingly attractive renewable resource that needs to be upgraded to meet either the natural gas pipeline quality or the biomethane requirement. The use of carbon membranes is a promising alternative to conventional separation technologies, but, up to now, few attempts have been made to systematically investigate their separation performance under real biogas upgrading conditions, for instance, the presence of water vapor and H2S in the feed stream.In this work, for the first time in literature, the separation performances of as-prepared cellulose-based carbon hollow fiber membranes were monitored for 183 days under continuous exposure to a gas stream also containing H2S and/or water vapor. After the evaluation of their CO2 and CH4 sorption (2,98 mmol g−1 and 2,00 mmol g−1, respectively at 298 K and 10 bar), diffusion(2.45 × 10-7 cm2 s−1 for CO2), and permeation properties (120.9 and 2.3 barrer, respectively at 308 K) with single gases, long-term tests were carried out by feeding gas mixtures with typical biogas composition. It was found that the exposure of the membranes to H2S (up to 500 ppm) and water vapor (relative humidity of 90%) provoked a reduction of CO2 and CH4 permeability compared to the “clean and dry” mixed gas, which resulted in an increment of selectivity, which reached a value of more than 200. Overall, after more than 180 days of continuous testing, the membranes exhibited remarkable CO2/CH4 selectivity with endurability of the H2S and water vapor, confirming the fact of being good candidates for biogas upgrading.

Modelling and thermodynamic properties of pure CO2 and flue gas sorption data on South African coals using Langmuir, Freundlich, Temkin, and extended Langmuir isotherm models

Carbon sequestration in unmineable coal seams has been proposed as one of the most attractive technologies to mitigate carbon dioxide (CO2) emissions in which CO2 is stored in the microporous structure of the coal matrix in an adsorbed state. The CO2 adsorption process is hence considered one of the more effective methodologies in environmental sciences. Thus, adsorption isotherm measurements and modelling are key important scientific measures required in understanding the adsorption system, mechanism, and process optimization in coalbeds. In this paper, three renowned and reliable adsorption isotherm models were employed including Langmuir, Freundlich, and Temkin for pure CO2 adsorption data, and the extended-Langmuir model for multicomponent, such as flue gas mixture-adsorption data as investigated in this research work. Also, significant thermodynamics properties including the standard enthalpy change (Delta H^circ), entropy change (Delta S^circ), and Gibbs free energy (Delta G^circ) were assessed using the van’t Hoff equation. The statistical evaluation of the goodness-of-fit was done using three (3) statistical data analysis methods including correlation coefficient (R2), standard deviation (σ), and standard error (SE). The Langmuir isotherm model accurately represent the pure CO2 adsorption on the coals than Freundlich and Temkin. The extended Langmuir gives best experimental data fit for the flue gas. The thermodynamic evaluations revealed that CO2 adsorption on the South African coals is feasible, spontaneous, and exothermic; and the adsorption mechanism is a combined physical and chemical interaction between the adsorbate and the adsorbent.

Zirconium Containing Periodic Mesoporous Organosilica: The Effect of Zr on CO2 Sorption at Ambient Conditions

Two series of zirconium-incorporated-periodic-mesoporous-organosilica (Zr–PMO) materials were successfully prepared, via a co-condensation strategy, in the presence of Pluronic P123 triblock copolymer. The first series of Zr–PMO was prepared using tris[3-(trimethoxysilyl)propyl]isocyanurate (ICS), tetraethylorthosilicate (TEOS), and zirconyl chloride octahydrate(ZrCO), denoted as Zr-I-PMO, where I refers to ICS. The second series was synthesized using bis(triethoxysilyl)benzene (BTEE), TEOS, and ZrCO as precursors, named as Zr-B-PMO, where B refers to BTEE. Zr–PMO samples exhibit type (IV) adsorption isotherms, with a distinct H2-hysteresis loop and well-developed structural parameters, such as pore volume, pore width, high surface area, and narrow pore-size distribution. Structural properties were studied by varying the Zr:Si ratio, adding TEOS at different time intervals, and changing the amount of block copolymer-Pluronic P123 used as well as the calcination temperature. Surface characteristics were tailored by precisely controlling the Zr:Si ratio, upon varying the amount of TEOS present in the mesostructures. The addition of TEOS at different synthesis stages, notably, enhanced the pore size and surface area of the resulting Zr-I-PMO samples more than the Zr-B-PMO samples. Changing the amount of block copolymer, also, played a significant role in altering the textural and morphological properties of the Zr-I-PMO and Zr-B-PMO samples. Optimizing the amount of Pluronic P123 added is crucial for tailoring the surface properties of Zr–PMOs. The prepared Zr–PMO samples were examined for use in CO2 sorption, at ambient temperature and pressure (25 °C, 1.2 bar pressure). Zr–PMO samples displayed a maximum CO2 uptake of 2.08 mmol/g, at 25 °C and 1.2 bar pressure. However, analogous zirconium samples, without any bridging groups, exhibited a significantly lower CO2 uptake, of 0.72 mmol/g, under the same conditions. The presence of isocyanurate- and benzene-bridging groups in Zr-I-PMO and Zr-B-PMO samples enhances the CO2 sorption. Interestingly, results illustrate that Zr–PMO materials show potential in capturing CO2, at ambient conditions.

Synthetic silico-metallic mineral particles SSMMP: A new option for CO2 capture and CO2/N2 separation from post-combustion technology

A new class of solid adsorbents based on pristine and ionic liquid (IL) functionalized synthetic silico-metallic mineral particles (SSMMP) for CO2 capture and CO2/N2 separation are presented. Pristine particles were submitted to hydrothermal treatment producing synthetic talc. Samples were characterized by thermal analyses (TGA), specific surface area measurements (BET), infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction(XRD), NMR spectroscopy, and scanning electron microscopy (SEM). Values for specific surface areas varied from 5 m2/g for a sample with high IL content to 354 m2/g for pristine SSMMP. Samples presented distinct morphology as well as sorption capacities. IL and its increased concentration in the samples negatively influenced CO2 sorption capacity but played an essential role in CO2/N2 selectivity. The best results were obtained from CO2 sorption values for SSMMP-M1 without IL of 2.07 mmol CO2/g at 1 bar and 4.93 mmol CO2/g at 30 bar. In addition, a selectivity of 16.94 for the CO2/N2 mixture was achieved for SSMMP-5%-Im(nBu)-I sample. SSMMP particles are easy to obtain with low-cost starting materials used in the low energy and CO2-free emission synthesis process. The sorption/desorption cycles proved the stability for both pristine and IL functionalized samples.

Boosting Electrocatalytic CO 2 Reduction with Conjugated Bimetallic Co/Zn Polyphthalocyanine Frameworks

Boosting Electrocatalytic CO ₂ Reduction with Conjugated Bimetallic Co/Zn Polyphthalocyanine Frameworks

Characteristics of MgO-based sorbents for CO2 capture at elevated temperature and pressure

MgO-based sorbents are promising candidates for precombustion CO2 capture performed at elevated temperature and pressure in thermodynamics, where the development of efficient sorbents is of great importance. Herein, we report MgO-Na2CO3-KNO3 sorbents with fast sorption kinetics, high capture capacity and good cyclic stability at elevated conditions. The effects of nitrate species, Na2CO3 doping amounts and sorption conditions on the MgO conversion were investigated during cyclic test. In comparison with LiNO3 and NaNO3, the sample with KNO3 possesses the highest MgO conversion, which increases from 0.78 to 0.86 after 30 cycles with sorption at 400 °C, 2 MPa. For nitrate-promoted MgO, Na2CO3 plays an essential role in the initial fast sorption rate. The sorbent with 60 mol%Na2CO3 possesses the highest MgO conversion of 0.89 after 30 cycles. Moreover, during the operation range of 400 ℃-480 ℃, 2 MPa, the sorbent exhibits an excellent cyclic stability with porous structure. Density functional theory calculations are further conducted to investigate the mechanism of performance improvement brought by Na2CO3. We find dissolved CO32– ions will provide chemisorption sites through the formation of C(CO2)-O(CO32–) bonds and can serve as the CO2 carrier in molten nitrate salts, thus improving both sorption and diffusion rates of CO2.