scholarly journals Pressureless and Low-Pressure Synthesis of Microporous Carbon Spheres Applied to CO2 Adsorption

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5328
Author(s):  
Iwona Pełech ◽  
Daniel Sibera ◽  
Piotr Staciwa ◽  
Urszula Narkiewicz ◽  
Robert Cormia
Keyword(s):  
Co2 Adsorption ◽  
Applied Pressure ◽  
Low Pressure ◽  
Spherical Particles ◽  
Co2 Uptake ◽  
Pressure Treatment ◽  
Carbon Spheres ◽  
Potassium Oxalate ◽  
Uniform Size ◽  
Pressure Synthesis

In this work, low-pressure synthesis of carbon spheres from resorcinol and formaldehyde using an autoclave is presented. The influence of reaction time and process temperature as well as the effect of potassium oxalate, an activator, on the morphology and CO2 adsorption properties was studied. The properties of materials produced at pressureless (atmospheric) conditions were compared with those synthesized under higher pressures. The results of this work show that enhanced pressure treatment is not necessary to produce high-quality carbon spheres, and the morphology and porosity of the spheres produced without an activation step at pressureless conditions are not significantly different from those obtained at higher pressures. In addition, CO2 uptake was not affected by elevated pressure synthesis. It was also demonstrated that addition of the activator (potassium oxalate) had much more effect on key properties than the applied pressure treatment. The use of potassium oxalate as an activator caused non-uniform size distribution of spherical particles. Simultaneously higher values of surface area and total pore volumes were reached. A pressure treatment of the carbon materials in the autoclave significantly enhanced the CO2 uptake at 25 °C, but had no effect on it at 0 °C.

scholarly journals Carbon Spheres as CO2 Sorbents

2019 ◽  
Vol 9 (16) ◽  
pp. 3349 ◽  
Author(s):  
P. Staciwa ◽  
U. Narkiewicz ◽  
D. Sibera ◽  
D. Moszyński ◽  
R. J. Wróbel ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Specific Surface ◽  
Co2 Adsorption ◽  
Solvothermal Method ◽  
Carbonization Temperature ◽  
Adsorption Properties ◽  
Carbon Dioxide Adsorption ◽  
Carbon Spheres ◽  
Potassium Oxalate ◽  
Microwave Assisted

Microporous nanocarbon spheres were prepared by using a microwave assisted solvothermal method. To improve the carbon dioxide adsorption properties, potassium oxalate monohydrate and ethylene diamine (EDA) were employed, and the influence of carbonization temperature on adsorption properties was investigated. For nanocarbon spheres containing not only activator, but also EDA, an increase in the carbonization temperature from 600 °C to 800 °C resulted in an increase of the specific surface area of nearly 300% (from 439 to 1614 m2/g) and an increase of the CO2 adsorption at 0 °C and 1 bar (from 3.51 to 6.21 mmol/g).

Unprecedented CO2 adsorption behaviour by 5A-type zeolite discovered in lower pressure region and at 300 K

2021 ◽  
Author(s):  
Akira Oda ◽  
Suguru Hiraki ◽  
Eiji Harada ◽  
Ikuka Kobayashi ◽  
Takahiro Ohkubo ◽  
...  
Keyword(s):  
Pressure Range ◽  
Co2 Adsorption ◽  
Low Pressure ◽  
Lower Pressure ◽  
Dft Studies ◽  
Adsorption Behaviour ◽  
Zeolite Sample ◽  
Pressure Region ◽  
Type Zeolite ◽  
Efficient Adsorbent

The NaCaA-85 zeolite sample which works as an efficient adsorbent for CO2 at RT and in low pressure range was found and its specificity is nicely explained by the model composed of CO2 pinned by two types of Ca2+ ions through far-IR and DFT studies.

scholarly journals Supercritical CO2 Exposure-Induced Surface Property, Pore Structure, and Adsorption Capacity Alterations in Various Rank Coals

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3294 ◽  
Author(s):  
Zhenjian Liu ◽  
Zhenyu Zhang ◽  
Xiaoqian Liu ◽  
Tengfei Wu ◽  
Xidong Du
Keyword(s):  
Coal Seam ◽  
Pore Structure ◽  
Adsorption Capacity ◽  
Surface Property ◽  
Supercritical Co2 ◽  
Co2 Adsorption ◽  
Low Pressure ◽  
Coal Seam Gas ◽  
Adsorption Sites ◽  
Co2 Adsorption Capacity

Carbon dioxide (CO2) has been used to replace coal seam gas for recovery enhancement and carbon sequestration. To better understand the alternations of coal seam in response to CO2 sequestration, the properties of four different coals before and after supercritical CO2 (ScCO2) exposure at 40 °C and 16 MPa were analyzed with Fourier Transform infrared spectroscopy (FTIR), low-pressure nitrogen, and CO2 adsorption methods. Further, high-pressure CO2 adsorption isotherms were performed at 40 °C using a gravimetric method. The results indicate that the density of functional groups and mineral matters on coal surface decreased after ScCO2 exposure, especially for low-rank coal. With ScCO2 exposure, only minimal changes in pore shape were observed for various rank coals. However, the micropore specific surface area (SSA) and pore volume increased while the values for mesopore decreased as determined by low-pressure N2 and CO2 adsorption. The combined effects of surface property and pore structure alterations lead to a higher CO2 adsorption capacity at lower pressures but lower CO2 adsorption capacity at higher pressures. Langmuir model fitting shows a decreasing trend in monolayer capacity after ScCO2 exposure, indicating an elimination of the adsorption sites. The results provide new insights for the long-term safety for the evaluation of CO2-enhanced coal seam gas recovery.

Revealing an unusual temperature-dependent CO2 adsorption trend and selective CO2 uptake over water vapors in a polyamine-appended metal–organic framework

2019 ◽  
Vol 3 (12) ◽  
pp. 2759-2767 ◽  
Author(s):  
Jong Hyeak Choe ◽  
Dong Won Kang ◽  
Minjung Kang ◽  
Hyojin Kim ◽  
Jeoung Ryul Park ◽  
...  
Keyword(s):  
Co2 Adsorption ◽  
Selective Adsorption ◽  
Metal Organic Framework ◽  
Co2 Uptake ◽  
Temperature Dependent ◽  
Water Vapors ◽  
Metal Organic ◽  
Adsorption Of Co ◽  
Unusual Increase ◽  
Organic Framework

Heavily tetraethylenepentamine (tepa)-functionalized Mg2(dobpdc) showed an unusual increase in CO2 uptake on increasing the temperature and selective adsorption of CO2 over water vapors.

scholarly journals Electrospun Composites Made of Reduced Graphene Oxide and Polyacrylonitrile-Based Activated Carbon Nanofibers (rGO/ACNF) for Enhanced CO2 Adsorption

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2117
Author(s):  
Faten Ermala Che Othman ◽  
Norhaniza Yusof ◽  
Javier González-Benito ◽  
Xiaolei Fan ◽  
Ahmad Fauzi Ismail
Keyword(s):  
Graphene Oxide ◽  
Activated Carbon ◽  
Reduced Graphene Oxide ◽  
Carbon Nanofibers ◽  
Co2 Adsorption ◽  
Morphological Properties ◽  
Co2 Uptake ◽  
Order Model ◽  
Activated Carbon Nanofibers ◽  
Reduced Graphene

In this work, we report the preparation of polyacrylonitrile (PAN)-based activated carbon nanofibers composited with different concentrations of reduced graphene oxide (rGO/ACNF) (1%, 5%, and 10% relative to PAN weight) by a simple electrospinning method. The electrospun nanofibers (NFs) were carbonized and physically activated to obtain activated carbon nanofibers (ACNFs). Texture, surface and elemental properties of the pristine ACNFs and composites were characterized using various techniques. In comparison to pristine ACNF, the incorporation of rGO led to changes in surface and textural characteristics such as specific surface area (SBET), total pore volume (Vtotal), and micropore volume (Vmicro) of 373 m2/g, 0.22 cm3/g, and 0.15 cm3/g, respectively, which is much higher than the pristine ACNFs (e.g., SBET = 139 m2/g). The structural and morphological properties of the pristine ACNFs and their composites were studied by Raman spectroscopy and X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM) respectively. Carbon dioxide (CO2) adsorption on the pristine ACNFs and rGO/ACNF composites was evaluated at different pressures (5, 10, and 15 bars) based on static volumetric adsorption. At 15 bar, the composite with 10% of rGO (rGO/ACNF0.1) that had the highest SBET, Vtotal, and Vmicro, as confirmed with BET model, exhibited the highest CO2 uptake of 58 mmol/g. These results point out that both surface and texture have a strong influence on the performance of CO2 adsorption. Interestingly, at p < 10 bar, the adsorption process of CO2 was found to be quite well fitted by pseudo-second order model (i.e., the chemisorption), whilst at 15 bar, physisorption prevailed, which was explained by the pseudo-first order model.

Microstructure and Spectroscopy of Lu2O3:Eu Prepared Using Various Synthesis Techniques

2004 ◽  
Vol 99-100 ◽  
pp. 25-30 ◽  
Author(s):  
E. Zych ◽  
J. Trojan-Piegza ◽  
L. Kępiński ◽  
P. Dorenbos
Keyword(s):  
Uniform Distribution ◽  
Spherical Particles ◽  
Nanocrystalline Powders ◽  
Nanocrystalline Powder ◽  
Homogeneous Precipitation ◽  
Uniform Size ◽  
X Ray ◽  
Methods Of Synthesis ◽  
Excited Luminescence ◽  
Subsequent Decomposition

Nanocrystalline powders of Lu2O3:Eu with activator content varying between 0.2%-10% were prepared using four different methods of synthesis. The products differed in their microstructure and crystallites sizes. Combustion of Lu(NO3)3 with urea produced strongly agglomerated material, most probably with significantly non-uniform distribution of the Eu3+ dopant. Replacing urea with glycine for the combustion produced only slightly agglomerated, voluminous, fluffy powder. Applying the Pechini technique resulted in significantly agglomerated powder while the homogeneous precipitation of Lu(OH)3 with urea at 90 °C and its subsequent decomposition to Lu2O3 at 650 °C resulted in a powder of perfectly spherical particles with a uniform size of about 130 nm with very low agglomeration. The efficiency of X-ray excited luminescence of our nanocrystalline Lu2O3:5%Eu was compared to that of the commercial microcrystalline Gd2O2S:Eu. It was found that the commercial phosphor performed four times more efficiently than our nanocrystalline powder. We consider this to be rather encouraging as the fabrication of our powder is not optimized yet. It seems that Lu2O3:Eu, even in nanocrystalline form, can perform much more efficiently which would make it a promising X-ray phosphor.

Notizen: Hochdrucksynthese und Einkristall-Strukturverfeinerung von Calciumaurat(III), CaAu2O4 / High Pressure Synthesis and Single-Crystal Structure Refinement of Calcium Aurate (III), CaAu2O4

1996 ◽  
Vol 51 (5) ◽  
pp. 747-750 ◽  
Author(s):  
Anja Louzikova ◽  
Klaus-Jürgen Range
Keyword(s):  
High Pressure ◽  
Structure Refinement ◽  
Three Dimensional ◽  
Pressure Treatment ◽  
Partial Structure ◽  
High Pressure Treatment ◽  
Square Planar ◽  
Ca Ions ◽  
Pressure Synthesis ◽  
Type Apparatus

Single crystals of calcium aurate(III), CaAu2O4, were obtained by high-pressure treatment of a CaO/Au2O3/KO2 mixture at 40 kbar, 1200 °C in a modified Belt-type apparatus. The crystals are tetragonal, space group I41/a, with a = 5.9868(7), c = 10.043(1) Å, c/a = 1.678 and Z = 4.CaAu2O4 is isostructural with LaPd2O4, SrAu2O4 and BaAu2O4. Its structure comprises square-planar AuO4 groups (< Au-O > = 2.007 Å), which are stacked into columns along [100] and [010], These columns are connected by shared corners forming a three-dimensional framework. The Ca ions are situated in tunnels created by the gold-oxygen partial structure. They are surrounded by eight oxygen atoms (<Ca-O> = 2.490 Å) in a slightly distorted dodecahedron.

A Model for Optimizing Material Removal Rate in Low-Pressure CMP: Effects of Pad Porosity and Abrasive Concentration

2008 ◽  
Author(s):  
Dinc¸er Bozkaya ◽  
Sinan Mu¨ftu¨
Keyword(s):  
Material Removal Rate ◽  
Chemical Mechanical Polishing ◽  
Material Removal ◽  
Removal Rate ◽  
Applied Pressure ◽  
Low Pressure ◽  
Mechanical Polishing ◽  
Low K

The necessity to planarize ultra low-k (ULK) dielectrics [1], and the desire to reduce polishing defects leads to use of lower polishing pressures in chemical mechanical polishing (CMP). However, lowering the applied pressure also decreases the material removal rate (MRR), which causes the polishing time for each wafer to increase. The goal of this work is to investigate effects of pad porosity and abrasive concentration on the MRR.

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