CO2 Adsorption Properties Research Articles

Efficient crystal structure materials as reactive sorbent for the CO2 and CH4 adsorption and storage

The efficient dirubidium cobalt bis(dihydrogendiphosphate) dihydrate compound is successfully synthesized in a solution and used as a reactive sorbent for the CO2 and CH4 gases adsorption and storage. A crystal of this Rb2Co(H2P2O7)2·2H2O compound has been isolated and characterized by single X-ray diffraction analysis and was found to crystallize in the triclinic system (P1¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$P\\overline{1}$$\\end{document}) with the cell parameters (Å): 6.980(1), 7.370(1), 7.816(1), 81.74(1), 70.35(1), 86.34(1); V = 374.68(9) Å3, Z = 2. The crystal-packing consists of a three-dimensional framework made upon corners and edges sharing of [RbO7], [H2P2O7] and [CoO6] entities, furthermore linked by a network of H-bonds. The UV–Vis spectroscopy revealed usual transitions between the ground state 4T1g and the upper levels 4T2g, 4A2g and 4T1g (P). Moreover, the CO2 and CH4 gases sorption measurements were successfully performed at two different temperatures (25 and 45 °C) and various pressures ranging from vacuum to 50 bar. Our results show that rate of CO2 and CH4 capturing was 3.10 mmol/g and 2.35 mmol/g at temperature 25 °C and pressure 50 bar, respectively. This compound showed a clear potential for CO2/CH4 adsorption and storage thereby paving the way towards its exploration and adaptation for capturing and collecting carbon dioxide and greenhouse gases from the air, and their conversion into hydrocarbon fuels using existing mature technologies. We have also conducted density functional theory calculations to study the CO2 and CH4 adsorption properties of Rb2Co(H2P2O7)2·2H2O. The simulation results show enhanced adsorption of both types of molecules on the surface of the material.

A comparative DFT study on the adsorption properties of lithium batteries thermal runaway gases CO, CO2, CH4 and C2H4 on pristine and Au doped CdS monolayer

The thermal runaway gases, such as CO, CO2, CH4, and C2H4, will leak from the battery electrolyte when lithium batteries in extreme discharge or thermal runaway conditions. The structural properties, differential charge density (DCD), density of state (DOS), gas adsorption properties, desorption time, work function and front-orbit theory calculation of pristine and Au doped CdS monolayer are explored and compared by first-principle calculation. The adsorption energy of CO, CO2, CH4 and C2H4 on the surface of Au–CdS are –0.89 eV, –0.40 eV, –0.14 eV and –0.77 eV, respectively. After doping, the adsorption type of CO and C2H4 are chemical type. Partial density of states shows that the gas molecules react with doped precious metal atoms. The adsorption ability of Au–CdS can be ranged as CO>C2H4>CO2>CH4. C2H4 on the surface of Au–CdS can desorb within 10 s at room temperature. As a result, Au–CdS exhibits tremendous prospective application as CO or C2H4 gas sensor. This study demonstrates that the adsorption and sensing properties of CdS monolayer can be improved effectively by the introduction of precious metal.

Single-Component Adsorption Equilibria of CO2, CH4, Water, and Acetone on Tapered Porous Carbon Molecular Sieves.

Engineered carbon molecular sieves (CMSs) with tapered pores, high surface area, and high total pore volume were investigated for their CO2, CH4, water, and acetone adsorption properties at 288.15, 298.15, 308.15 K, and pressures of <1 bar. The results were compared with BPL carbon. The samples exhibited higher adsorption capacity for CO2 compared to BPL carbon, with Carboxen 1005 being the highest due to the presence of ultramicropores (pores smaller than 0.8 nm). Similar observations were made for CH4 except at 288.15 K. Although the CMSs exhibited higher hydrophobicity than BPL carbon, the latter had the highest acetone uptake for all investigated temperatures due to its higher oxygen content, which facilitates stronger interactions with polar VOC molecules. Heats of adsorption were calculated using the Clausius-Clapeyron equation after fitting the isotherms with the dual-site Langmuir-Freundlich model, and results largely corroborated the order of adsorption capacities of CO2, CH4, and water on the carbon materials.

Photocatalytic degradation of organic dyes using reduced graphene oxide (rGO)

Photocatalysts have developed into a successful strategy for degrading synthetic and organic toxins, such as chemicals and dyes, in wastewater. In this study, graphene oxide was reduced at different temperatures and used for degrading indigo carmine and neutral red dyes. The wide surface areas, strong adsorption sites, and oxygen functionalities of reduced graphene oxide (rGO) at 250 °C (rGO-250) produced more photocatalytic degradation efficiency and adsorption percentage. The catalyst dosage, initial dye concentration, solution pH and recyclability were all used to optimize the photocatalytic activity of rGO-250. This research presents a capable nano-adsorbent photocatalyst for the efficient degradation of organic dyes. GO and rGOs were also investigated for carbon dioxide (CO2) absorption properties. Results showed that rGO-250 has better CO2 adsorption properties than other rGOs. Overall, it was observed that rGO-250 has better photocatalytic and CO2 adsorption capabilities compared to graphene oxide reduced at different temperatures.

Research on the adsorption of Co2+ ions using halloysite clay and the ability to recover them by electrodeposition method

Abstract In environmental research, along with discovering methods for adsorbing heavy metals, it is essential to comprehend the processes of desorption and recovery of these heavy metals from adsorbent materials and their reuse. In this study, halloysite (HAL) clay, obtained from the Thach Khoan, Vietnam, was utilized for the removal of Co2+ ions from an aqueous solution, and the influence of different factors on the adsorption properties of Co2+ was investigated. Optimal conditions determined were 0.8 g HAL mass per 50 mL of solution, initial Co2+ concentration of 40 mg·L−1, contact time of 80 min, pH0 of 6.09, and room temperature of 30°C. Under these conditions, the adsorption efficiency and capacity obtained were 76.358 ± 0.981% and 1.909 ± 0.025 mg·g−1, respectively. The adsorption process followed the Langmuir adsorption isotherms, with a maximum monolayer adsorption capacity of 3.10206 ± 0.13551 mg·g−1, and exhibited a pseudo-second-order kinetic model. Desorption experiments were conducted using the electrochemical method with a deep eutectic solvent based on choline chloride and urea (reline). The results demonstrated that 94.11% of the Co metal could be recovered through electrodeposition after 5 h, using an applied current of 7.5 mA at 60°C. The HAL material was successfully regenerated following the desorption process.

The potential application of cellulose acetate membrane for CO2 adsorbent

ABSTRACT Numerous countries have deployed significant efforts to reduce the amount of CO2 released into the atmosphere. Carbon capture and storage is widely regarded as a mitigation technique that can significantly reduce CO2 emissions. A crucial stage in carbon capture and storage is CO2 adsorption using a membrane. Cellulose acetate has demonstrated excellent properties as a membrane material. In this study, we examined the potential of cellulose acetate membrane (CAM) for CO2 gas capture. Two forms of CAM were developed for this study, with and without the addition of glycerol. Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR), and CO2 adsorption analyses were used to characterise CAM in numerous ways. The analysis revealed that the addition of glycerol improved the gas adsorption properties of the material. The incorporation of glycerol into the cellulose acetate matrix resulted in an observed augmentation in both the diameter and pore size. The adsorption properties of CO2 are significantly influenced by the microscopic structure of the cellulose acetate membrane. The CAM can be viewed as a possible material for CO2 adsorbers.

Probing Structural Transformations and Degradation Mechanisms by Direct Observation in SIFSIX-3-Ni for Direct Air Capture.

Despite global efforts to reduce carbon dioxide (CO2) emissions, continued industrialization threatens to exacerbate climate change. This work investigates methods to capture CO2, with a focus on the SIFSIX-3-Ni metal-organic framework (MOF) as a direct air capture (DAC) sorbent. SIFSIX-3-Ni exhibits promising CO2 adsorption properties but suffers from degradation processes under accelerated aging, which are akin to column regeneration conditions. Herein, we have grown the largest SIFSIX-3-Ni single crystals to date, facilitating single crystal X-ray diffraction analyses that enabled direct observation of the H2O and CO2 dynamics through adsorption and desorption. In addition, a novel space group (I4/mcm) for the SIFSIX-3-Ni is identified, which provided insights into structural transitions within the framework and elucidated water's role in degrading CO2 uptake performance as the material ages. In situ X-ray scattering methods revealed long-range and local structural transformations associated with CO2 adsorption in the framework pores as well as a temperature-dependent desorption mechanism. Pair distribution function analysis revealed a partial decomposition to form nonporous single-layer nanosheets of edge-sharing nickel oxide octahedra upon aging. The formation of these nanosheets is irreversible and reduces the amount of active material for the CO2 sorption. These findings provide crucial insights for the development of efficient and stable DAC sorbents, effectively reducing greenhouse gases, and suggest avenues for enhancing MOF stability under practical DAC conditions.

Preparation of Li4SiO4 from lithium-ion battery cathode waste and diamond wire saw silicon powder using a two-step process

Li4SiO4 materials have excellent high-temperature CO2 adsorption properties. In this thesis, Li4SiO4 was produced by a two-step process by using Li+ from waste lithium-ion battery cathodes as a partial lithium source. The diamond wire saw silicon powder generated by the photovoltaic industry, was used as the silicon source. The reduction melting process of LiMeO2 (Me = Ni, Co, or Mn) in the battery cathode material was analyzed, and the effect of the Li: Si molar ratio in the melting system on the reduction of metal oxides was investigated. The effects of roasting temperature and roasting time on the adsorption properties of Mn-doped Li4SiO4 were also studied. The results showed that the maximum adsorption capacity of Mn-doped Li4SiO4 reached 29.44 wt% under a pure CO2 atmosphere, which was about 2.6 times higher than that of pure Li4SiO4. The saturated adsorption capacity reached 34.2 wt%. This study achieved the resource utilization of solid waste and may reduced the preparation costs of Li4SiO4 adsorbent, which may promote carbon capture technologies.

Stability, electronic properties and CO adsorption properties of bimetallic PtAg/Pt(111) surfaces.

Aiming at a better fundamental understanding of the chemistry of bimetallic PtAg/Pt(111) surfaces, we have investigated the stability, electronic properties and CO adsorption properties of bimetallic PtAg surfaces, including pseudomorphic Ag film covered Pt(111) surfaces and PtxAg1-x/Pt(111) monolayer surface alloys, using periodic density functional theory calculations. The data provide detailed insights into the relative stabilities of different surface configurations, as indicated by their formation enthalpies and surface energies, and changes in their electronic properties, i.e., in the projected local densities of states and shifts in the d-band center. The adsorption properties of different Ptn ensembles were systematically tested using CO as a probe molecule. In addition to electronic ligand and strain effects, we were particularly interested in the role of different adsorption sites and of the local COad coverage, given by the number of CO molecules per Pt surface atom in the Ptn ensemble. Different from PdAg surfaces, variations in the adsorption energy with adsorption sites and with increasing local coverage are small up to one COad per Pt surface atom. Finally, formation of multicarbonyl species with more than one COad per Pt surface atom was tested for separated Pt1 monomers and can be excluded at finite temperatures. General trends and aspects are derived by comparison with comparable data for PdAg bimetallic surfaces. Fundamental insights relevant for applications of bimetallic Pt catalysts, specifically PtAg catalysts, are briefly discussed.

Preparation of [BMIM]HSO4@SiO2 Ionic Liquid Microcapsules and Application to CO2 Adsorption

Carbon emissions are closely related to global climate change and have gradually become a focus of attention. Carbon capture is an effective way to reduce carbon emissions, ionic liquid microcapsules (ILM) have great potential as a CO2 capture material. [BMIM]HSO4@SiO2 ionic liquid microcapsules were prepared by in situ polymerization, and the microcapsule samples were characterized using thermo-gravimetric analysis & differential scanning calorimetry (TG/DSC), scanning electron microscopy (SEM), laser particle size analysis and surface area analyser. The microcapsules on the CO2 adsorption properties were investigated. The results showed that the microcapsule particles have a smooth spherical morphology and uniform size, the average particle size was 146 μm. The TG/DSC showed the microcapsules have better thermal stability. From 273 K isothermal adsorption curve of microcapsules, the sample can reach the maximum adsorption capacity of 4.87 cm3/g STP (standard pressure).

Construction of Zn-Cu bimetallic metal-organic frameworks for carbon dioxide capture.

Bimetallic metal-organic frameworks (MOFs) have shown more impressive performance in gas adsorption compared with monometallic MOFs. Herein, a Cu-Zn bimetallic metal-organic framework (Zn/Cu-BTC) was synthesized via a one-pot method, and its structure, thermal stability and CO2 adsorption property were investigated and compared with those of corresponding monometallic Cu-BTC and Zn-BTC. The results showed that Zn/Cu-BTC has a specific ortho-octahedral crystal morphology with a unique X-ray diffraction peak, the atomic ratio of Zn to Cu is about 1 : 5, and it remained stable at a temperature up to 490 K. In Zn/Cu-BTC, Cu2+ played a role in increasing the specific surface area and porosity of the MOF and improving the gas adsorption performance. The CO2 adsorption of Zn/Cu-BTC is lower than that of Cu-BTC but much higher than that of Zn-BTC, and CO2 adsorption heat was 30.52 kJ mol-1, which indicated physical adsorption. In addition, Zn/Cu-BTC had higher CO2/N2 adsorption selectivity compared with Zn-BTC and Cu-BTC, with a maximum value of 17. This study can be a reference for the research on improving the adsorption selectivity of gases by constructing bimetallic MOFs.

Microscopic Mechanism of Fe2O3-Catalyzed NO Reduction during Sludge Combustion: A Density Functional Theory Study

Systematic studies on the mechanism underlying Fe2O3-catalyzed NO reduction in a reducing atmosphere during sludge combustion remain limited. In this study, density functional theory was employed to investigate the adsorption properties of NH3, CO, and NO on the α-Fe2O3(001) surface, and the mechanisms underlying the NH3 and CO reduction of NO during the adsorption process. The results demonstrated that NH3, CO, and NO chemically adsorbed on the surface Fe top site, thereby generating distinctly high adsorption energies. NO exhibited the highest adsorption energy. With regard to the catalytic mechanisms of NH3 and CO during NO reduction, the α-Fe2O3(001) surface exhibited different characteristics. NH3 reduction of NO tended to follow the Eley–Rideal (E-R) mechanism. The dissociation of -NH2NO is the rate-determining step for the NH3 reduction of NO. The presence of α-Fe2O3(001) reduced the dissociation energy barriers of NH3 and NH2NO, thereby catalyzing the reduction reaction. In contrast, NO dissociation was more challenging during the CO reduction of NO. The α-Fe2O3(001) surface reduced the dissociation barrier of the NO-NO dimer from 2.04 to 1.53 eV. Two adsorbed NO molecules first formed NO-NO dimers; these then dissociated into N2O and atomic oxygen, thereby catalyzing the reduction reaction.

Insight into the adsorption properties of CO2 and H2 gas on the B12Y12 (Y[dbnd]N, P, As, Sb) nanocages from host-guest interaction perspective

Owing to the huge increase in population and industrial activity over the past century, the natural air environment is becoming increasingly polluted. Therefore, it is essential to monitor and regulate pollution levels. Numerous research efforts have been conducted to create acceptable gas-sensitive materials for continuing monitoring and sounding alarms when dangerous chemical vapors are present at higher than intended levels. In the theoretical analysis of the adsorption properties, density functional theory calculations were utilized for B12Y12 (YN, P, As, Sb) nanocages as gas sensor towards common air pollutants, CO2 and H2 molecules. In this study, the geometrical and electronic properties, highest occupied molecular orbital (HOMO) – lowest unoccupied molecular orbital (LUMO) energy gap, frontier molecular orbital (FMO) analysis were investigated. The shortest H2 and CO2 distances after the adsorption process were for B12N12 with distances less than 2.8 Å and 2.2 Å, respectively, and the adsorption energy when CO2 was adsorbed on the B12N12 surface was less than −26 kJ/mol, indicating that adsorption occurred physically and exorthemically. The Eg of B12N12 is 5.9 eV; therefore, compared to others, this nanocage is the most stable for H2 and CO2 adsorption. In addition, a positive ∇2ρ value and negative H value from the QTAIM analysis indicated the formation of moderate interaction between B12N12 and CO2. Density of states (DOS) and natural bond orbital (NBO) studies were performed to better understand the nanocage adsorption properties, which revealed the presence of physical interactions. Energy decomposition analysis was performed to investigate the stability of gas adsorption onto a nanocage surface. The results showed that ΔEDISP and ΔEELEC were significant factors in determining the adsorption process stability, and the adsorption type was physisorption based on ΔEPOL value for all nanocages. Molecular dynamics (AIMD simulation) analysis revealed changes in the bond lengths and angles during adsorption. This work provides the first theoretical framework for the carbon monoxide and hydrogen adsorption performance of B12Sb12 and B12As12.

Composite nanofibrous membranes with two-dimensional ZIF-L and PVDF-HFP for CO2 separation

Membrane gas-solvent contactors show effective CO2 capture as compared to solvent absorption. However, the overall efficiency of the capture process is compromised by the relatively low CO2 transfer rate of existing commercial membranes. Herein, we propose the integration of a two-dimensional zeolitic imidazolate framework (ZIF-L) with outstanding CO2 adsorption properties into porous poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibre membranes for energy-efficient CO2 separation through membrane gas absorption. Well-defined composite structures of the nanofibre membranes with ZIF-L are fabricated using the electrospinning technique. The favourable adsorption of CO2 molecules in the unique cushion-shaped cavities of ZIF-L enhances CO2 flux during both absorption and stripping processes even under mild temperature conditions when utilised in the composite nanofibre membranes. Consequently, the PVDF-HFP membrane with 5 wt% ZIF-L presents 26.7 mmol m−2 s−1 of CO2 stripping flux at 100 °C.

Porous organic polymer containing Tröger’s base skeleton and crown ether for cycloaddition of CO2 and efficient iodine vapor adsorption

A wide range of templating reagents containing crown ether-based Tröger's base structure and coordinating of various co-catalysts were synthesized by polymerization, and characterized using various analytic techniques. Their catalytic performance for CO2 conversion and adsorption properties for iodine vapor were examined. Delightfully, after CETB-X recognized with HBr, all exhibited excellent catalytic activity in the presence of cetyltrimethylammonium bromide. The best-performing catalyst could convert CO2 into cyclic carbonate with a yield of 93.1% under optimal reaction conditions. Furthermore, CETB-C16Br/C16N+Br- possessed excellent stability and substrate suitability with six times without any significant loss of catalytic activity. A preliminary kinetic study was investigated using CETB-C16Br/C16N+Br- and the activation energy has been calculated to be 41.51 kJ/mol. All of these polymers also exhibited iodine adsorption capacities above 3.0 g/g, with the most powerful adsorption reaching 4.68 g/g. Through kinetic simulations, the adsorption process was simulated as a pseudo-first-order kinetic model.

Ultrahigh performance CO2 capture and separation in alkali metal anchored 2D-COF

The development of advanced adsorbents with high CO2 capture and separation performances is essential for decreasing atmospheric CO2 concentration. Herein, grand canonical Monte Carlo and density functional theory were employed to investigate the adsorption and separation properties of CO2, N2, and CH4 in 2D covalent organic framework (COFs) anchored by alkali metal (AMs) Li, Na, and K (UPC-nAMs, n = 3 or 6) at 298 K and 0–1.0 bar. The anchoring of AMs formed favorable adsorption sites, endowing UPC-nAMs with better CO2 capture and separation performances. This effect was more evident with an increase in Li/Na/K concentration. The CO2 adsorption capacity of UPC-6Li/Na/K was ∼ 221.64, 188.28, and 140.50 cm3 cm−3. The smaller atomic size of Li occupied less adsorption space, resulting in the highest CO2 capture capacity of 221.64 cm3 cm−3 with selectivity of 308/206 over N2/CH4 in UPC-6Li at 298 K and 1.0 bar. Structural stability, pore characteristics, isothermal adsorption heat, van der Waals and Coulomb interactions, gas distribution density, adsorption configuration, and gas radial distribution function were analyzed to identify the intrinsic mechanism of anchoring Li/Na/K to improve CO2 capture and separation performances.

Molecular simulation of the adsorption and diffusion properties of CH4 and CO2 in the microporous system of coal

Micropores are the main adsorption sites for gases in coal. The research of the adsorption and diffusion pattern of gases in micropores is important for CO2-ECBM engineering and other measures to improve production. In this study, a multiscale microporous system with intramolecular pores, intermolecular pores, and slit pores is proposed. Adsorption and diffusion characteristics of CH4 and CO2 in different microporous systems were investigated. The results show that the adsorption of different microporous systems is basically consistent at low pressures (<2 MPa). Upon further increase in pressure, adsorption increases with increasing slit pore size. Gas molecules in coal are preferentially adsorbed in the intramolecular and intermolecular pores, and gas molecules in the slit pores are preferentially adsorbed in the slit pore walls. The increase in gas pressure and slit pore size decreases the proportion of gases adsorbed in the intramolecular and intermolecular pores and also increases the proportion adsorbed in the slit pores. Increase in size of the slit pores and decrease in adsorption will result in an increase in self-diffusion coefficients of gases. The results of self-diffusion coefficients of pores with different scales indicate that slit pores have the largest self-diffusion coefficients, followed by the intermolecular pores, and the smallest for the intramolecular pores. The isosteric heat of gases tends to decrease and then increase with increasing adsorption. The increase of slit pore size will decrease interaction energy. This study gives a reference for adsorption and diffusion mechanisms of gases in microporous systems, as well as a basis for gas injection displacement studies.

Ethane-CO2 Mixture Adsorption in Silicalite: Influence of Tortuosity and Connectivity of Pores on Selectivity

Selective adsorption using nanoporous materials is an efficient strategy for separating gas mixtures. In a nanoporous material, pores can exist in different shapes and can have different degrees of inter-connectivity. In recent studies, both pore connectivity and tortuosity have been found to affect the adsorption and dynamical properties of ethane and CO2 in silicalite differently. Here, using Monte Carlo simulations, we investigate if these two attributes can affect the selective adsorption of one component from a mixture of ethane and CO2 in silicalite. For this, the adsorption of an equimolar mixture of ethane and CO2 is simulated in 12 models of silicalite—SnZm (n, m = 0, 1, 2, 3 or 4; with n and m denoting, respectively, the fraction (out of 4) of straight and zigzag channels of silicalite that are available for adsorption)—differing in degrees of pore connectivity and tortuosity. The adsorption selectivity in this system is found to exhibit a reversal with the adsorption dominated by ethane at low pressures (below ~1 atm) and by CO2 at higher pressures (above ~10 atm). Pore connectivity is found to suppress the selective adsorption of CO2 at higher pressures and also shifts the selectivity reversal to higher pressures. The selectivity reversal results from a competition between the polarizability-affected adsorption at lower pressures and efficient packing at higher pressures. The efficient packing of CO2 is a compounded effect resulting from the larger effective pore volume available for CO2 due to its stronger interaction with the pore surface and smaller molecular volume. CO2 molecules show a preference to adsorb in non-tortuous pores, and this preference is found to be stronger in the presence of ethane. The effects of pore connectivity and tortuosity elucidated here should be applicable to a wide range of natural and engineered nanoporous materials, and this knowledge could be used to identify materials with better capability for separating and storing CO2 based on their pore attributes.

Investigation of the promotion effect of metal oxides on the water-gas shift reaction activity over Pt-MOx/CeO2 catalysts for aqueous phase reforming

Aqueous phase reforming (APR) of methanol is a potential pathway for the effective hydrogen production under relatively mild conditions. The Pt/CeO2 and a series of Pt-MOx/CeO2 (M = Fe, Cr, Mg, Mn) catalysts were prepared by sequential impregnation method and their APR reaction performances were studied. The catalyst properties including valence state of the promoters, the amount of oxygen vacancies, the metal distributions, the adsorption properties of CO and the acidity/basicity of catalysts were characterized and analyzed by XPS, XRD, TEM, CO-TPD, NH3-TPD, CO2-TPD, etc. It was found that the addition of MOx weakened the Pt-CeO2 interaction and promoted the generation of Ptδ+ species with lower valence state, which contribute to the C–H bond cleavage and facilitate methanol conversion. The highest hydrogen production (164.78 mmol) and relatively low CO and CH4 selectivities were obtained over the Pt-MgO/CeO2, while the highest CH4 selectivity was obtained over the Pt-CrOx/CeO2 (2.21%). Over the Pt/CeO2 and Pt-MOx/CeO2 (M = Fe, Cr, Mg, Mn) catalysts, CO2/CH4 ratio correlated well with the catalyst basicity, indicating that the basicity promotes the dissociation adsorption of H2O as well as the water-gas shift (WGS) reaction activity and decreases the methanation activity.

CO2 adsorption properties of Ni-BDC MOF and its 1–8 wt% g-C3N4/Ni-BDC MOF

The substantial challenge that the world is facing nowadays, is the increase in greenhouse gasses which causes global warming. Therefore, there must be a technique to overcome its global emission rate. Accordingly, many absorbents and adsorption techniques are used to capture the CO2 gas. Here, this study reports a novel class of adsorbents Metal Organic Framework (MOF) and its g-C3N4 based composites are used to adsorb CO2. The synthesis of Ni-BDC MOF and its 1–8 wt% g-C3N4/Ni-BDC MOF composites were successfully prepared via the solvothermal method. These samples are characterized by using different techniques like XRD, EDX, SEM, FTIR to investigate the structural and morphological properties. The MOFs and their composites were studied for CO2 adsorption and desorption at a temperature of 25 °C and 0–15 bar pressure. Among all the composites, 5 wt% g-C3N4/Ni-BDC MOF shows the highest adsorption capacity of 0.50 mmol/g. The rising adsorption trend of all prepared materials shows that these samples do not reach their saturation point and can still adsorb more CO2 even at pressure higher than 15 bar.