Adsorption of carbon dioxide on hydrotalcite-like compounds of different compositions

Porous hyper-cross-linked aromatic polymers are one ofthe emergingclasses of porous organic polymers with the potential for industrialapplication. Four different porous polymeric materials have been preparedusing different precursors (indole, pyrene, carbazole, and naphthalene),and the composition and textural properties were analyzed. The materialswere characterized in detail using different physicochemical techniqueslike scanning electron microscopy, transmission electron microscopy,nitrogen adsorption at 77 K, Fourier transform infrared spectroscopy,X-ray diffraction, etc. The effect of textural properties and nitrogenspecies on carbon dioxide and nitrogen adsorption capacities and selectivitywas studied and discussed. The carbon dioxide and nitrogen adsorptioncapacities were measured using a volumetric gas adsorption system.The adsorption data were fitted into different adsorption models,and the ideal absorbed solution theory was used to calculate adsorptionselectivity. Among the studied samples, POP-4 shows the highest carbondioxide and nitrogen adsorption capacities. While POP-1 shows maximumCO2/N2 selectivity of 78.0 at 298 K and 1 barpressure. It is observed that ultra-micropores, which are presentin the prepared materials but not measured during conventional surfacearea measurement via nitrogen adsorption at 77 K, play a very importantrole in carbon dioxide adsorption capacity and determining the carbondioxide selectivity over nitrogen. Surface nitrogen also increasesthe CO2 selectivity in the dual mode by increasing carbondioxide adsorption via the acid–base interaction as well asby decreasing nitrogen adsorption due to N–N repulsion.

Selective adsorption of supercritical carbon dioxide and methane binary mixture in shale kerogen nanopores

The adsorption capacities of carbon dioxide on six commercial hydrotalcite-like compounds and the main factors (aluminum content, anion type, water content, and heat treatment temperature) influencing their adsorption capacity at high temperatures have been investigated using a gravimetric technique. There is an optimum aluminum content and heat treatment temperature for the adsorption capacity. The carbonate anion favors adsorption of carbon dioxide compared to OH-, and a low content of water also improves the adsorption capacity. The carbon dioxide adsorption capacity is mainly dependent on the microporous volume, interlayer spacing, and layer charge density of the hydrotalcite-like compounds.

Surface thermodynamics of hydrocarbon vapors and carbon dioxide adsorption on shales

Hydrotalcite-like compounds as adsorbents for carbon dioxide

The adsorption capacity of carbon dioxide on high surface area carbon-based adsorbents before and after chemical modification at 28°C and 300°C have been studied. The high adsorption capacity adsorbents for carbon dioxide at high temperature have been developed by introducing MgO and S–CaO–MgO on carbon-based adsorbents. Their adsorption capacities for carbon dioxide were 0.28 and 0.22 m mol/g at 300°C, 1 Bar, respectively.

The development of new methods for obtaining nitrogen-containing sorbents to bind carbon dioxide is an important task to combat climate change, minimize a carbon trace and obtain industrially valuable products in heterogeneous catalytic processes. In this regard, the effect of the temperature of pyrolysis of polyphenylenepyridines on the chemical composition and sorption. The X-ray photoelectron spectroscopy (XPS) method was used to demonstrate the formation of nitrogen-containing products of high-temperature (800 − 1000 °C) carbonization of polyphenylenepyridines and polybiphenylenepyridines containing surface hydroxyl, ether, and carboxyl functional groups. According to the study of carbon dioxide adsorption-desorption isotherms, the new materials have a specific surface area of about 1000 m2g−1 and a micropore diameter of up to 0.48 nm (Non-Local Density Functional Theory (NLDFT)). The resulting carbon materials had a high adsorption capacity for carbon dioxide, as well as the ability to cooperatively desorb it in accordance with the second-order kinetic equation. It was shown that the rate of carbon dioxide desorption decreased with increasing pyrolysis temperature used to form nitrogen-containing carbon material. Simultaneously with increasing pyrolysis temperature, a decrease in the mass fraction of nitrogen in the samples was observed with an increase in the adsorption capacity of the formed adsorbents with respect to carbon dioxide. Thus, the increase in the specific surface had a greater effect on the amount of carbon dioxide adsorption than the N/C value ratio did.

To mitigate the greenhouse effect, a number of porous organic polymers (POPs) has been developed for carbon capture. Considering the permanent quadrupole of symmetrical CO2 molecules, the integration of electron-rich groups into POPs is a feasible way to enhance the dipole-quadrupole interactions between host and guest. To comprehensively explore the effect of pore environment, including specific surface area, pore size, and number of heteroatoms, on carbon dioxide adsorption capacity, we synthesized a series of microporous POPs with different content of β-ketoenamine structures via Schiff-base condensation reactions. These materials exhibit high BET specific surface areas, high stability, and excellent CO2 adsorption capacity. It is worth mentioning that the CO2 adsorption capacity and CO2/N2 selectivity of TAPPy-TFP reaches 3.87 mmol g-1 and 27. This work demonstrates that the introduction of β-ketoenamine sites directly through condensation reaction is an effective strategy to improve the carbon dioxide adsorption performance of carbon dioxide.

Carbon dioxide, a type of greenhouse gases has drawn world wide’s attention as major contributors to global warming and climate change. Thus, several methods have been developed to mitigate this problem such as through adsorption. There are numerous types of adsorbents available, for instance is carbon-based adsorbent that can be synthesised from various type of biomass as reported in previous studies. However, there are very few studies used soil as an adsorbent for gases. Soils are porous medium developed in the uppermost layer of Earth’s crust which are available in several forms, abundance and cheap. In this study, three types of carbonised soils were used as carbon-based adsorbent to investigate its adsorption capacity for carbon dioxide. Influence of moisture content in this study is negligible as it is too low. Due to the nature of raw materials used, ash content for all sample was incredibly high which almost all exceeded 90%. Determination of densities by pycnometer showed that carbonised soil 2 has the lowest particle and bulk density of 2.4802 g/cm3 and 0.5248 g/cm3 respectively. Then the adsorption capacity of each sample was determined by sorption measuring instrument with magnetic suspension balance. Results showed that carbonised soil 2 with high surface area, pore volume, and small pore size has the highest adsorption capacity of 6.4 mg/g at 25 ˚C under atmospheric pressure. Therefore, soils exhibit prominent potential to be developed as carbon dioxide adsorbent with desirable properties.

Influence of nickel oxide on carbon dioxide adsorption behaviors of activated carbons

Adsorption technology has emerged as a viable approach to reducing CO2 emissions. Generally, activated carbons-based adsorbents, in particular, are promising due to their abundant availability, tunable physicochemical properties, and suitability over a wide temperature range. In this study, activated carbons (ACC) modified with magnesium oxide (MgO) was evaluated for carbon dioxide capture in an adsorption process. ACC, the feedstock, was produced using the fast pyrolysis of Astragalus. The availability and cheapness of the Astragalus material next to MgO led to the synthesis of a new compound called ACC/MgO. The aim of this new synthetic compound was to achieve a cost-effective approach to carbon dioxide adsorption. This approach somehow shows the innovation of the work. Another innovation is adsorbent moulding (monolith) and its industrialisation. The synthetic material underwent various analyses, including FTIR, XRD, SEM, BET, and EDX. Fifteen experiments were designed using the response surface methodology-Box-Behnken (RSM-BBD) design to determine the maximum carbon dioxide adsorption capacity (ADC). One of the optimal points, with the highest carbon dioxide ADC (1.355 mmol/g), was determined at an initial MgO loading of 13.26 wt.%, an average ACC particle size of 0.58 mm, and a Polyvinyl alcohol (PVA) content of 6.34 wt.%. Kinetic models and isotherm models were employed to analyse the adsorption data. The findings indicated that the entire adsorption range could be described by employing the fractional-order model. Investigation into the diffusion mechanism revealed that both film diffusion and intraparticle diffusion predominantly governed the rate-limiting steps. The adsorbent exhibited favourable regeneration at lower temperatures and demonstrated consistent regenerability following seven cycles of adsorption and regeneration. This research demonstrated that ACC modified with MgO is a suitable adsorbent due to its high capacity and efficiency in carbon dioxide capture.

Significance of extra-framework monovalent and divalent cation motion upon CO2 and N2 sorption in zeolite X

Five nitrogen sources (glycine, β‐alanine, urea, melamine and nicotinamide) and three heating methods (thermal, monomodal microwave and multimodal microwave) are used to prepare nitrogen‐doped Starbons® derived from starch. The materials are initially produced at 250–300 °C (SNx300y), then heated in vacuo to 800 °C to produce nitrogen‐doped SNx800y’s. Melamine gives the highest nitrogen incorporation without destroying the Starbon® pore structure and the microwave heating methods give higher nitrogen incorporations than thermal heating. The carbon dioxide adsorption capacities of the nitrogen‐doped Starbons® determined gravimetrically, in many cases exceed those of S300 and S800. The carbon dioxide, nitrogen and methane adsorption isotherms of the most promising materials are measured volumetrically. Most of the nitrogen‐doped materials show higher carbon dioxide adsorption capacities than S800, but lower methane and nitrogen adsorption capacities. As a result, the nitrogen‐doped Starbons® exhibit significantly enhanced carbon dioxide versus nitrogen and methane versus nitrogen selectivities compared to S800.

In this study, commercial wool felts were valorized as sustainable precursor materials for the fabrication of activated carbon fiber adsorbents aimed at carbon dioxide capture. The production process involved a sequential treatment comprising oxidative stabilization, carbonization, and chemical activation using potassium hydroxide. The structural and surface properties of the resulting activated carbon fibers were characterized by elemental analysis, scanning electron microscopy, and Brunauer–Emmett–Teller surface area analysis. The effects of carbonization temperature and KOH impregnation ratio on textural properties and carbon dioxide adsorption capacity were systematically investigated. In addition, precursor wool felts were modified with chitosan prior to thermochemical processing to assess its influence on carbon dioxide uptake performance. The developed activated carbon fibers exhibited highly microporous structures, with specific surface areas exceeding 1700 m 2 /g and dominant pore diameters below 1 nm. Under the applied testing conditions, the maximum carbon dioxide adsorption capacity reached 4.06 mmol/g. Furthermore, chitosan modification improved adsorption efficiency. These findings underscore the feasibility of utilizing wool‐based precursors for the sustainable production of high‐performance activated carbon fibers, presenting a renewable alternative to conventional fossil‐derived adsorbent materials.

Molecular level investigation of methane and carbon dioxide adsorption on SiO2 surface