Study Of CO Adsorption Research Articles

Study of CO2 Adsorption on Chemically Modified Activated Carbon With Nitric Acid and Ammonium Aqueous.

The study of CO2 adsorption on adsorbent materials is a current topic of research interest. Although in real operating circumstances, the removal conditions of this gas is carried out at temperatures between 290 and 303 K and 1 Bar of pressure or high pressures, it is useful, as a preliminary approach, to determine CO2 adsorption capacity at 273K and 1 Bar and perform a thermodynamic study of the CO2 adsorption heats on carbonaceous materials prepared by chemical activation from African palm shell with CaCl2 and H3PO4 solutions, later modified with HNO3 and NH4OH, with the aim to establish the influence that these treatments have on the textural and chemical properties of the activated carbons and their relationship with the CO2 adsorption capacity. The carbonaceous materials were characterized by physical adsorption of N2 at 77K, CO2 at 273K, proximate analysis, Boehm titrations and immersion calorimetry in water and benzene. Activated carbons had a BET area between 634 and 865 m2g−1, with a micropore volume between 0.25 and 0.34 cm3g−1. The experimental results indicated that the modification of activated carbon with HNO3 and NH4OH generated a decrease in the surface area and pore volume of the material, as well as an increase in surface groups that favored the adsorption of CO2, which was evidenced by an increase in the adsorption capacity and the heat of adsorption.

Enhancement of D2/H2 Selectivity in Zeolite A through Partial Na–K Exchange: Single-Gas and Coadsorption Studies at 45–77 K

We report D2/H2 adsorption selectivities under cryogenic temperatures (45–77 K) in Na and K–Na exchanged zeolites A (LTA structural code) measured by a coadsorption technique. These values are syst...

Effect of modification of UiO-66 for CO2 adsorption and separation of CO2/CH4

UiO-66 and TETA/UiO-66 were synthesized by the solvothermal and impregnation methods for the study of CO2 adsorption and separation of CO2/CH4 by volumetric method. Adsorbents were characterized by X-ray diffraction (XRD), N2 adsorption-desorption isotherm (BET analyzer), FT-IR spectroscopy, Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM), and elemental analysis. All characterization results have confirmed that incorporated TETA was present and occupied pores of UiO-66. High adsorption of CO2 was obtained for 25TETA/UiO-66 compared with UiO-66 by chemical interaction between CO2 and adsorbent. Along with this, a decrease in CH4 adsorption has been observed by a change in surface area and no interaction between them. The selectivity of CO2/CH4 was higher for 25TETA/UiO-66 because of the large difference in adsorption capacities of CO2 and CH4. The heat of CO2 adsorption for TETA incorporated UiO-66 was 54.6 KJ/mol at low coverage of CO2 and CO2 adsorption capacity was constant in multiple adsorption cycles.

First-principles study of CO adsorption on Os atom doped anatase TiO2 (1 0 1) surface

In this paper, the adsorption of CO on the three anatase TiO2 (101) surface systems of intrinsic TiO2, an oxygen vacancy modification (VO/TiO2), and co-modified by an oxygen vacancy and a doped noble metal atom Os (Os/TiO2) are studied by first-principles. The results show that the adsorption performance of CO on intrinsic TiO2 is fine; especially the adsorption performance is greatly improved after adding defects. The adsorption energies of the TiO2 system, the VO/TiO2 system, and the Os/TiO2 system are −0.552 eV, −1.591 eV, and −3.971 eV, respectively. By analyzing the adsorption energy (ΔEads), bond length, charge distribution, density of states (DOS) and charge differential density (CDD) of the three systems, it is found that their adsorption mechanism and adsorption methods are different. The intrinsic TiO2 system is physical adsorption, and the carbon atom in CO has a strong interaction with Ti5C, but they cannot form bonds. The VO/TiO2 system is chemical adsorption, and the carbon atom of CO exerts a strong interaction with Ti2, resulting in a C-Ti2 bond. The Os/TiO2 system is chemical adsorption, and the strong interaction between carbon atom of CO and OS atom causes the formation of C-Os bond.

Comparative Adsorption Isotherm for Beryllium Oxide/Iron (III) Oxide Toward CO<sub>2</sub> Adsorption and Desorption Studies

Surface modification of Fe2O3 by adding BeO was synthesized and calcined at different temperatures of 200-600 °C. The adsorbents were characterized by using XRD, N2 adsorption-desorption isotherm prior to performing CO2 adsorption and desorption studies. The CO2 adsorption data were analyzed using adsorption isotherm models such as Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich. BeO/Fe2O3-300 that calcined at 300 °C showed the most efficient adsorbent with physisorption and chemisorption were measured at 5.85 and 45.88 mg/g respectively. The CO2 adsorption notably best fitted with Freundlich isotherm with R2 = 0.9897 and calculated adsorption capacity closest to experimental data. This implies the CO2 adsorption process was governed by multilayer adsorption on the heterogeneous surface of the adsorbent. The mean free energy of adsorption (E=3.536 kJ/mol) from Dubinin-Radushkevich and heat of adsorption (bT=3.219 kJ/mol) from the Temkin model support that the adsorption process is physical phenomena.

Methanol oxidation over copper supported catalysts.

Oxidation of methanol has been studied over a range of temperature and contact times with a synthesised, 1wt % copper catalysts supported over Al2O3 and SiO2. Characterisation of these catalysts was performed by nitrogen adsorption and porosity measurements (BET), X-Ray Diffraction (XRD), and IR spectroscopy of adsorbed CO. BET measurement revealed surface areas reducing from 105 to 104 m2g-1 for pure alumina to copper supported catalyst while the silica ones reduced from 247 to 240 m2g-1 for pure silica to the copper supported respectively. Pore sizes also reduced from 32 – 23 nm and 23 – 20.3 nm for the alumina and silica catalysts respectively. No crystalline phases from the diffraction patterns of the loaded metals were found to be present on the XRD. CO adsorption studies showed the presence of small cluster metal atoms adsorbed on the surface of the catalysts with Temperature Programmed Reduction (TPR) experiments revealing the presence of partially oxidised and well dispersed Cu atoms. The alumina supported catalyst were more active than the silica ones while for selectivity and yield for formaldehyde, the reverse was the case. The alumina supported significantly showed high yields of Dimethyl ether (DME) while the silica showed high yield for methyl formate (MF) with COx and CH4 detected in very small quantities.

KIT-6 Üzerinde CO2 Adsorpsiyon Davranışı ve Kinetiği Üzerine Bir Çalışma

KIT-6 mesoporous silica has been used in catalysis, nano containers, adsorption and drug delivery applications due to its original three dimensional channel network. Typically, KIT-6 is prepared from triblock copolymers as the template directing agents under acidic conditions. In this article, KIT-6 was successfully synthesized via partitioned cooperative self-assembly method. The synthesized sample was characterized using X-ray diffraction (XRD), thermogravimetry/differential thermal analysis (TG/DTA) and N2 adsorption/desorption. The characterization methods demonstrated that the synthesized sample is ordered KIT-6 mesoporous silica with a high surface area (605.93 m2 g-1), pore volume (0.58 cm3 g-1), and good thermal stability. The CO2 adsorption studies of the sample were performed at different temperatures (25, 75 and 100°C). The maximum adsorption capacity (0.65 mmol g-1) was observed at 25°C adsorption temperature. In addition, it was determined that the adsorption capacity of KIT-6 decreases with increasing adsorption temperature. This study also presents the investigation of the CO2 adsorption kinetics on KIT-6 using the first order and the second order models. The kinetic data for the CO2 adsorption on the sample conformed to the second order model. The activation energy (Ea) was calculated as 18.75 kJ mol-1 from Arrhenious plot for CO2 adsorption on KIT-6 mesoporous silica. Moreover, the regenerability and cyclic stability of KIT-6 mesoporous silica was determined using TG/DTA analysis. From the analysis results, it was clearly seen that the ordered mesoporus silica has perfect cyclic stability of 94% after 4 adsorption/desorption cycle, which implies that the synthesized KIT-6 could possibly used as an adsorbent in the CO2 adsorption.

Comparative Density Functional Theory Study of Cinchonidine and Hydrogen Coadsorption on Platinum Group Metals (Rh, Ir, Pd, and Pt) and Its Implications on Surface Chiral Site Formation

Coadsorption of hydrogen and cinchonidine (CD), the chiral modifier most frequently applied to bestow chiral sites onto platinum group metals, has been studied theoretically. In focus was the stabi...

Porous carbon supported calcium oxide for CO2 adsorption and separation of CO2/CH4

ABSTRACT Calcium oxide incorporated porous carbon materials were synthesized by the impregnation method to study CO2 adsorption and separation of CO2/CH4. The X-ray diffraction, Raman analysis, N2 isotherms at 77 K, and SEM with EDX analysis were used to characterize synthesized materials. XRD and N2 isotherm results have confirmed that synthesized carbon has porosity, and EDX analysis has reported that the presence of CaO on porous carbon. 10CaO/porous carbon has shown 31 cm3 g−1 of CO2 adsorption which was higher than bare porous carbon CO2 adsorption 17.5 cm3 g−1 at 298 K, 1 bar. It was attributed to electrostatic interaction between CaO and CO2. However, CH4 adsorption was decreased by a decrease in surface area. The selectivity of CO2/CH4 was higher for 10CaO/porous carbon and the heat of CO2 adsorption was 36 KJ/mol at high adsorption of CO2. Moreover, CO2 adsorption was the same in each adsorption cycle.

A comparison of nano-scale pore attributes of Barakar Formation gas shales from Raniganj and Wardha Basin, India using low pressure sorption and FEG-SEM analysis

This study investigates the micropore-mesopore spectrum in gas shales by augmenting two different pore size distribution calculation methods using two probe gases in low-pressure sorption analysis. The Barakar Formation shale samples collected from Wardha and Asansol belonging to two key potential basins in India, namely Wardha and Raniganj, were studied to identify possible variations in pore attributes in shales, and a comparison was drawn. A combination of CO2 and N2 low-pressure gas adsorption studies was implemented to resolve micro- and meso-pores, using the respective probe adsorbate. The visual representation of the pore structure and its disposition was facilitated by high-resolution microscopic imaging, and aided by image analysis. The results show a positive correlation between clay mineral composition and the mesopore attributes as well as organic matter composition and micropore attributes. This confirms that both inorganic and organic content of shales contains large pore volumes, albeit in different pore dimension ranges with some overlap. High N2 adsorption potential of Asansol shale, as well as high CO2 adsorption potential of Wardha valley shale, is conformable with their respective pore size distributions. Fractal characteristics of mesopores suggest that the larger mesopores have a rougher surface, whereas the smaller mesopores have a smoother surface (with average fractal dimensions of 2.6 and 2.2, respectively). Although all examined shales belong to the same geological formation, they exhibit distinctly variable pore attributes and gas storage potential.

Study of CO2 adsorption and separation using modified porous carbon

Porous carbon and La2O3/porous carbon materials are synthesized for the study of CO2 adsorption and separation by the volumetric method. The synthesized adsorbents are characterized by X-ray diffraction, N2 adsorption–desorption isotherms, Raman spectra and scanning electron microscopy with energy-dispersive X-ray analysis. Characterization results confirm the existence of porosity in the synthesized carbon materials and uniform distribution of lanthanum(III) oxide on porous carbon. The CO2 adsorption capacity for porous carbon and La2O3/porous carbon is 21 and 33 cm3 g−1, respectively, at 298 K and 1 bar. High adsorption of CO2 is obtained for La2O3/porous carbon because of the electrostatic interaction between La2O3 and CO2. Moreover, the N2 adsorption capacity is 2.8 cm3 g−1 for porous carbon and 2.2 cm3 g−1 for La2O3/porous carbon at 298 K and 1 bar. The change in N2 adsorption is due to the decrease in surface area. For La2O3/porous carbon, the selectivity of CO2/N2 is 33.5 and the heat of CO2 adsorption is 36.5 kJ mol−1 at low adsorption of CO2. It also shows constant CO2 adsorption capacity in each adsorption cycle.

Simulation study of fixed-bed CO2 adsorption from CO2/N2 mixture using activated carbon

An experimental and simulation study using a packed column for CO2 sorption was conducted. The adsorption data of CO2 sorption from CO2/N2 mixture using activated carbon (NORIT RB1) were obtained at different operating conditions. The sorption equilibrium and breakthrough profiles were produced with a total pressure of 1.25 bars. The breakthrough and saturation time decreased with increasing temperature, feed rate, and inlet CO2 concentration. A linear driving force (LDF) model for mass transfer was used to calculate the mass transfer coefficient and reproduce the breakthrough curves. The findings of the LDF model were compared with experimental data produced at various operating conditions to predict the breakthrough curves. The experimental and predicted findings were analyzed by ascertaining the determination coefficient and mean error. The model consistently reproduced all the breakthrough curves and may be considered adequate for predicting the CO2 separation from a CO2/N2 mixture with R 2 > 0.97 and mean error less than 5% under all the operating conditions.

In Situ X-ray Diffraction Study of Xe and CO2 Adsorption in Y Zeolite: Comparison between Rietveld and PCA-Based Analysis

New very fast and efficient detectors, installed both on laboratory instruments and synchrotron facilities, allow the monitoring of solid-state reactions from subsecond to minute scales with the production of large amounts of data. Traditional “one-by-one” pattern refinement needs complementary approaches, useful to handle hundreds to thousands of X-ray patterns. Principal-component analysis (PCA) has been applied to these fields in the last few years to speed up analysis with the specific goals of assessing data quality, identifying patterns where a reaction occurs, and extracting the kinetics. PCA is applied to the adsorption/desorption of Xe and CO2 within a Y zeolite. CO2 sequestration is a key issue in relation to climate change, while Xe is a critical raw material, and its purification is an important topic for the industry. At first, results were compared to traditional sequential Rietveld refinement. CO2-Y data were also compared with in situ single crystal data to investigate the different potentialities of PCA in the two cases. Two CO2 adsorption sites were confirmed, while three Xe sites were identified. CO2 showed a more linear adsorption trend with decreasing temperature, while Xe showed a more sigmoidal-like trend. Xe only showed site-dependent behavior in adsorption. Finally, PCA and correlation analysis, applied to analyze the parameters obtained from Rietveld refinement, highlighted finer details: in particular, this approach showed that the Y zeolite framework responded differently to CO2 and Xe adsorption.

Preliminary Study of Chitosan Coating Silica Derived from Geotermal Solid Waste

Purpose: The purposes of this research are to study preparation of chitosan coating silica aerogel derived from solid geothermal waste as adsorbent of CO2 and CH4 separation and to study CO2 adsorption kinetics on chitosan coating silica aerogel by Pseudo First Order and Second Order methods. Methodology was conducted consisting of several steps. First, geothermal silica was leached with H2SO4 20% 1: 5 w/v. Then, chitosan was added into silica with ratio of 1.3: 10, 1.5: 10, 1.9: 10, 2.2: 10, and 2.4: 10 w/v. Isopropyl alcohol was added to silica sol to form hydrogel and remained in gelation. The addition of n-hexane was carried out to occur the solvent exchange process. The gel was dried by ambient pressure drying method. CO2 in biogas was removed of using 20 g of adsorbent chitosan coating silica aerogel. The experimental adsorption kinetics analyzed by both pseudo first and second order kinetics model. Results showed that impurities in geothermal silica required to be purified and it can be synthesized into silica aerogel. The remaining geothermal can act as adsorbents to silica aerogel coated with chitosan by using packed column. The data obtained was kinetics data from the pseudo first and second order method. The silica from solid geothermal waste has the potential as CO2 adsorbent. Applications/ Originality/ Value: It was confirmed that silica from solid geothermal waste can be used as CO2 adsorbent. Therefore, the improvement of innovation in the future of this research is to prepare chitosan coating silica aerogel as CO2 adsorbent.

A 3D interpenetrated Co(II)-glutarate coordination polymer: Synthesis, crystal structure, magnetic and adsorption properties

A 3D entangled coordination polymer {[Co4(glu)4(bpp)2]}n1 was synthesized from a solvothermal reaction between Co(II), glutaric acid (H2glu) and 1,3-bis(4-pyridyl)propane (bpp). The crystal structure was determined by single crystal X-ray diffraction and the topological description indicates a 3D → 3D interpenetration in the pcu-coordination polymer, pillared by bpp ligands. Crystal structure presents four crystallographically distinct Co(II) metal centers conferring different coordination environments: tetrahedral, octahedral and trigonal bipyramidal. Spectroscopic (FTIR and Raman), thermal analysis and magnetic studies were employed to chemical characterization. SQUID magnetometry analysis indicated weak overall antiferromagnetic interactions between the Co(II) ions. High-Field Electron Paramagnetic Resonance (HFEPR) spectra suggest that the Co(II) ions in compound 1 are high-spin (S = 3/2). The material showed good thermal stability decomposing above 300 °C. CO2 adsorption studies carried out in the pressure range of 0 to 40 bar at room temperature revealed a favorable solid-gas interaction at low pressure. The amount of CO2 adsorbed on compound 1 continuously increased as the pressure increased and no gas saturation is observed suggesting a multilayer phenomenon of CO2 uptake. Powder X-ray diffraction analysis of compound 1 after CO2 measurements at 40 bar revealed no structural change.

First-principles study of CO and NO adsorption on pristine and transition metal doped blue phosphorene

First-principles calculations within the density functional theory (DFT-D2 method) is carried out to systematically investigate the structural, energetic, electronic and magnetic properties of toxic CO and NO gas molecules on pristine and transition metal (TM) atom (Fe, Co, Ni, Pd, Ag and Pt) doped blue phosphorene. Our calculations show that the CO and NO molecules are physisorbed on pristine blue phosphorene due to small adsorption energies, charge transfer, and large adsorption distances of the adsorbed systems. TM doping can significantly enhance the interaction between the gas molecules and the blue phosphorene, leading to the CO and NO molecules absorbed on TM doped blue phosphorene belong to chemisorption with relatively large adsorption energies and charge transfer, except for CO adsorbed on Ag doped blue phosphorene. Meanwhile, the enhancing interaction between the gas molecules and TM doped blue phosphorene can dramatically induce magnetism and electrical conductivity changes. These results indicate that TM doped blue phosphorene is a potential candidate to develop novel two-dimensional phosphorene-based gas sensors.

Study of CO2 and H2O adsorption competition in the combined dry / steam reforming of biogas

The combined dry-steam reforming (CDSR) of a model biogas (66 % CH4 + 34 % CO2) has been investigated under various feed compositions and reaction temperature conditions over a Ni-Rh/MgAl2O4 catalyst, with the objective to convert the excess of methane (compared to CO2) by steam reforming (SR). Methane, however, appeared to react preferentially with H2O rather than with CO2, leading to an inhibition of the dry reforming (DR) reaction in the presence of steam. CO2 and H2O adsorption and co-adsorption studies revealed that H2O was always adsorbed in much higher amounts than CO2 on the catalyst surface. A Temkin adsorption model applied to temperature-programmed adsorption experiments (TPAE) showed that two different strongly adsorbed CO2 and H2O species were present on the catalyst surface at moderate temperature, but only one of each remained adsorbed at temperatures relevant to the reaction conditions (600−800 °C). H2O was also shown to displace CO2 from the catalyst surface, confirming that they compete, at least partially, for the same adsorption sites. At high temperature, the surface coverage by the most strongly adsorbed H2O species was predominant. These results should contribute to the development of efficient catalytic processes for biogas valorization to produce syngas and hydrogen from renewable sources.

Combined DRIFTS and DFT Study of CO Adsorption and Segregation Modes in Pt–Sn Nanoalloys

This contribution aims at rationalizing the observations made by in situ IR spectroscopy during CO adsorption over ca. 1.8 nm Pt–Sn nanoparticles by density functional theory (DFT) calculations and...

A mechanistic study of molecular CO2 interaction and adsorption on carbon implanted SnS2 thin film for photocatalytic CO2 reduction activity

Gas-phase photocatalytic reactions to convert carbon dioxide and water into oxygen and hydrocarbons are the foundation of life on earth. However, the efficiency of photosynthesis is relatively low (~1%), which leaves much room for artificial photosynthesis to reach the benchmark of the solar cells (>15%). In this work, carbon implanted SnS2 thin films (C–SnS2) were prepared to study photocatalytic activity and adsorbate-catalyst surface interactions during CO2 photoreduction. The electron density distribution in C–SnS2 and its contribution toward the photogenerated charge transfer process has been analyzed by the angle-dependent X-ray absorption near-edge structure (XANES) study. The C–SnS2 surface affinity toward the CO2 molecule was monitored by in-situ dark current and Raman spectroscopy measurements. By optimizing the dose during ion implantation, SnS2 thin film with 1 wt% carbon incorporation shows 108 times enhancement in the CO2 conversion efficiency and more than 89% product selectivity toward CH4 formation compared with the as-grown SnS2 without carbon incorporation. The improved photocatalytic activity can be ascribed to enhanced light harvesting, pronounced charge-transfer between SnS2 and carbon with improved carrier separation and the availability of highly active carbon sites that serve as favorable CO2 adsorption sites.

A microporous aluminum-based metal-organic framework for high methane, hydrogen, and carbon dioxide storage

We report a microporous aluminum-based metal-organic framework (MOF), BUT-22 for high methane (CH4), hydrogen (H2), and carbon dioxide (CO2) storage. At 296 K and 80 bar, BUT-22 exhibits a high gravimetric CH4 storage capacity of 530 cm3 (STP)/g (0.379 g/g). BUT-22 also has a high gravimetric H2 storage capacity of 12 wt.% at 100 bar and 77 K. In addition, the CO2 adsorption studies revealed that BUT-22 exhibits a high absolute gravimetric CO2 uptake of 1.7 g/g at 296 K and 40 bar.