“…The isotherms have a small hysteresis cycle at a relative pressure >0.4, indicating the presence of mesopores. − This behavior is present in the three samples obtained in the basic medium; although this cycle is located in the same relative pressure range in these materials and has a similar size, it is important to mention that the value of the surface area and the micropore volume of the carbonized sample decreased after the activation processes, except for the sample AAA650(H 2 O), probably due to the increase in the pore size by the degassing of the sample by thermal treatment in the presence of activating agents such as CO 2 and water vapor. − Low temperature is not effective for the physical activation of the carbons; − in the activation with CO 2 and H 2 O, carbon atoms are extracted according to the following reactions …”
Section: Resultsmentioning
confidence: 90%
“…Figure a,b shows the CO 2 and CH 4 adsorption isotherms at 30 °C and high pressure. These isotherms have a very similar shape that corresponds to the Langmuir type with an initial steep slope, which is associated with strong adsorbate–adsorbent interactions . According to the IUPAC classification, these CO 2 and CH 4 isotherms of adsorption are type I(b) and I(a), respectively; in these types of isotherms, the amount adsorbed increases rapidly with the increase in pressure due to the presence of micropores and reaches a plateau as the pores fill up .…”
Section: Adsorption Of Co2 and Ch4 At High Pressuresmentioning
In
the present work, the synthesis of aerogels was carried out
from a mixture of resorcinol–formaldehyde as the precursors.
The synthesis conditions used were those adjusted to obtain micropore
materials. These solids were obtained through two synthesis routes:
acid and base catalysis. The obtained materials were activated with
CO2 and water vapor. It was determined that the carbonization
of the aerogels obtained by the basic medium (ACB 1050) develops a
greater percentage of microporosity, which decreases after the activation
processes. The adsorption capacity of CO2 and CH4 at 50 bar on the surface of this material is 12.6 and 6.0 mmol g–1, respectively.
“…The isotherms have a small hysteresis cycle at a relative pressure >0.4, indicating the presence of mesopores. − This behavior is present in the three samples obtained in the basic medium; although this cycle is located in the same relative pressure range in these materials and has a similar size, it is important to mention that the value of the surface area and the micropore volume of the carbonized sample decreased after the activation processes, except for the sample AAA650(H 2 O), probably due to the increase in the pore size by the degassing of the sample by thermal treatment in the presence of activating agents such as CO 2 and water vapor. − Low temperature is not effective for the physical activation of the carbons; − in the activation with CO 2 and H 2 O, carbon atoms are extracted according to the following reactions …”
Section: Resultsmentioning
confidence: 90%
“…Figure a,b shows the CO 2 and CH 4 adsorption isotherms at 30 °C and high pressure. These isotherms have a very similar shape that corresponds to the Langmuir type with an initial steep slope, which is associated with strong adsorbate–adsorbent interactions . According to the IUPAC classification, these CO 2 and CH 4 isotherms of adsorption are type I(b) and I(a), respectively; in these types of isotherms, the amount adsorbed increases rapidly with the increase in pressure due to the presence of micropores and reaches a plateau as the pores fill up .…”
Section: Adsorption Of Co2 and Ch4 At High Pressuresmentioning
In
the present work, the synthesis of aerogels was carried out
from a mixture of resorcinol–formaldehyde as the precursors.
The synthesis conditions used were those adjusted to obtain micropore
materials. These solids were obtained through two synthesis routes:
acid and base catalysis. The obtained materials were activated with
CO2 and water vapor. It was determined that the carbonization
of the aerogels obtained by the basic medium (ACB 1050) develops a
greater percentage of microporosity, which decreases after the activation
processes. The adsorption capacity of CO2 and CH4 at 50 bar on the surface of this material is 12.6 and 6.0 mmol g–1, respectively.
“…These images show that our samples are very porous and are characterized by nanopores. Such as we have obtained in the study of Raman and XRD, these PF composites are amorphous [7].Fig. 5SEM de los aerogeles (A) y (B) CAePF OA 550, (C) y (D) CAePF HCl 1000.…”
Aerogels are extremely porous materials with large pore volumes and low bulk densities. Their unique structure imparts extraordinary properties and wide applications. The synthesis of pyrogallol-formaldehyde xerogels has been reported using HClO
4
as a catalyst, but according to the literature review the synthesis of aerogels of these materials has not been documented. In the present work, the data for the synthesis of aerogels pyrogallol-formaldehyde are presented using oxalic acid and hydrochloric acid as catalysts. Also includes the data of the characterization of these materials by Infrared spectroscopy, thermogravimetric analysis Tg-DTG, Physisorption of N
2
, Raman Spectroscopy, X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). It was determined that the use of these precursors of the synthesis of aerogels in acid medium, leads to the obtaining of microporous solids with a high value of the surface area, the material with the highest value of this parameter has been CAePF OA550 at have a BET area value of 1066 m
2
g
−1
.
“…Thus, the adsorption of CO2 under these experimental conditions will be favored than the CH4. We have shown in ourprevious works that the main factors acting on the adsorption properties of CO2 and CH4 are the specific surface area and the volume of the pores [45,46]. But we note that for this study as shown in the table 2, at low pressures (5 bar), the PF matrix has the highest adsorption capacity for the two gases and at high pressures (25 bar), the PF/NiO nanocomposite tends to adsorb gases better than the PF matrix.…”
Nanoporous carbon matrix was prepared by the sol-gel process from pyrogallol-formaldehyde (PF) mixtures in water using picric acid as catalyst. For the second sample, nickel oxide nanoparticles were added in the PF matrix to get a PF/NiO hybrid nanocomposite. The samples were heat treated at the pyrolysis temperature of 650 °C for two hours. The obtained materials have been characterized by different techniques such as: X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), differential thermalanalysis (DTA),nitrogen adsorption-desorption isotherms, voltage-current characteristics, electrochemical measurementsand UV-Vis-IR absorption. The XRD analysis shows that PF matrix is amorphous while PF/NiO nanocomposite exhibited a metallic phase of nickel. The SEM and TEM images indicated the presence of nickel particles in the PF/NiO nanocomposite which are dispersed randomly in the carbon matrix. The adsorption-desorption of nitrogen revealed that the PF matrix is microporous and the PF/NiO nanocomposite is mesoporous. The adsorption capacities of carbon dioxide (CO2) and methane (CH4) show that the PF matrix has the highest adsorption at low pressures and the PF/NiO nanocomposite tends to adsorb gasesbetter at high pressure. The V(I) characteristics showed that the PF/NiO nanocomposite can be considered as a smart material. Indeed, the characteristic behavior can be adjusted according to the maximum applied current. Electrochemical measurements have shown that the PF/NiO nanocomposite is very promising for the detection of non-enzymatic glucose. The absorption spectra showed that the addition of the NiO nanoparticles increased the disorder.The obtained materials are promoters for various applications such as gas storage, negatronic devices and glucose sensor.
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