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

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

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.

Surface thermodynamics of hydrocarbon vapors and carbon dioxide adsorption on shales

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

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.

A mononuclear square-planar CuII complex of (5-methyl-1H-pyrazol-3-yl)carbamate, [Cu(C5H6N3O2)2]·4H2O, was synthesized using a one-pot reaction from 5-methyl-3-pyrazolamine and copper(II) acetate in water under ambient conditions. The adsorption of carbon dioxide from air was facilitated by the addition of di-ethano-lamine to the reaction mixture. While di-ethano-lamine is not a component of the final product, it plays a pivotal role in the reaction by creating an alkaline environment, thereby enabling the adsorption of atmos-pheric carbon dioxide. The central copper(II) atom is in an (N2O2) square-planar coordination environment formed by two N atoms and two O atoms of two equivalent (5-methyl-1H-pyrazol-3-yl)carbamate ligands. Additionally, there are co-crystallized water mol-ecules within the crystal structure of this compound. These co-crystallized water mol-ecules are linked to the CuII mononuclear complex by O-H⋯O hydrogen bonds. According to Hirshfeld surface analysis, the most frequently observed weak inter-molecular inter-actions are H⋯O/O⋯H (33.6%), H⋯C/C⋯H (11.3%) and H⋯N/N⋯H (9.0%) contacts.

Copper oxide-decorated porous carbons for carbon dioxide adsorption behaviors

TeO2–V2O5–NiO thin films were deposited using thermal evaporation from 40TeO2–([Formula: see text])V2O5–yNiO ([Formula: see text]–30[Formula: see text]mol%) target. Structural analysis of the films was identified by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The amorphous TeO2–V2O5–NiO films have nanosized clear grain structure and sharp grain boundaries. DC conductivity and current–voltage (I–V) characteristic of TeO2–V2O5–NiO thin films were measured in the temperature range of 300–423[Formula: see text]K. As nickel oxide (NiO) content increases, the DC conductivity decreases up to two orders in value ([Formula: see text]–[Formula: see text][Formula: see text]S[Formula: see text][Formula: see text][Formula: see text]cm[Formula: see text]. Temperature dependence of conductivity is described using the small polaron hopping (SPH) model as well. Poole–Frenkel effect is observed at high external electric field. The optical absorption spectra of the TeO2–V2O5–NiO thin films were recorded in the wavelength range of 380–1100[Formula: see text]nm. The absorption coefficient revealed bandgap shrinkage (3.01–2.3[Formula: see text]eV) and band tail widening, due to an increase in NiO content. Energy dispersive X-ray spectroscopy (EDX) was used to determine elemental composition. In TeO2–V2O5–NiO thin films, the NiO content is around fifth of the initial target.

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.

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.

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

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.

In this study, activated carbon fibers (ACFs) were produced from mechanically recycled acrylic (PAN) and cotton (CO) fibers and their blend (PAN/CO) in felt form as an adsorbent for carbon dioxide capture. For this purpose, stabilization, carbonization, and chemical activation processes were applied consecutively. The effects of recycled fiber type, carbonization temperature, and activation agent impregnation ratio were investigated. The resultant ACFs were characterized by elemental analysis, SEM, FTIR, XPS, and BET analyses, and carbon dioxide adsorption capacity was tested. It was observed that the fibrous structure of all samples was preserved at all stages, although the fiber diameters were reduced. The maximum quantity of adsorbed CO2 was found to be 3.79, 3.47, and 3.28 mmol CO2/g for recycled PAN, CO, and PAN/CO based samples, respectively, at 298 K at a relative pressure of 0.989. It was conducted that the carbon dioxide adsorption performance was affected by both the ACF surface area and the nitrogen content in the structure. It was concluded that recycled fiber‐based ACFs as CO2 adsorbents could be successfully produced with reasonable adsorption performance as a sustainable alternative.Highlights Activated carbon fibers were produced from recycled acrylic and cotton fibers Fibrous structure was preserved, but fiber diameters decreased Reasonable carbon dioxide adsorption capacity was attained Recycled fiber‐based ACFs could be a sustainable alternative to CO2 adsorbents

Melamine-nitrogenated mesoporous activated carbon derived from rice husk for carbon dioxide adsorption in fixed-bed