scholarly journals An Overview of the Challenges and Progress of Synthesis, Characterization and Applications of Plugged SBA-15 Materials for Heterogeneous Catalysis

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5082
Author(s):  
Mozaffar Shakeri ◽  
ZeynabAlsadat Khatami Shal ◽  
Pascal Van Der Voort
Keyword(s):  
Thermal Stability ◽  
Heterogeneous Catalysis ◽  
Metal Complexes ◽  
Gas Adsorption ◽  
The Other ◽  
Organic Template ◽  
Molar Ratios ◽  
Desorption Isotherms ◽  
New Generation ◽  
Adsorption Desorption

A new generation of SBA-15, plugged SBA-15, was initially synthesized in 2002 using extra silica precursors (Si/organic template molar ratios ≈ 80–140) in the gel mixture. The plugged SBA-15 materials possess short cylinders (length ≈ 20–100 nm), which are connected to neighbors by constricted entrances (windows) through the central axis. The gas adsorption–desorption isotherms of plugged SBA-15 materials present unique hysteresis loop Type H5 classification identified by IUPAC in 2015, which is related to certain pore structures containing open and plugged mesopores. The plugged SBA-15 has been used to support various types of catalysts, including metal complexes, metal nanocatalysts, and active metals by the incorporation in their framework demonstrating excellent (enantio)selectivity, stability against coke, and thermal stability. The plugged SBA-15 materials bear the other unique properties of the ship-in-the-bottle synthesis of, e.g., metal complexes that confine homogeneous catalysts, which is not possible by conventional SBA-15 due to leaching. In this mini-review, the challenges and progress of the synthesis in controlling the plugging and incorporation of metals and organic moiety in their framework, characterizing the short mesochannel dimensions (window and length sizes) by several advanced techniques and applying plugged SBA-15 materials in heterogeneous catalysis for challenging reactions, has been discussed.

Coal gas adsorption/desorption isotherms versus diffusion process

2016 ◽  
Vol 9 (4) ◽  
pp. 467 ◽  
Author(s):  
Cristina Fernanda Rodrigues ◽  
Maria Alzira Pimenta Dinis ◽  
Manuel Joao Lemos de Sousa
Keyword(s):  
Diffusion Process ◽  
Gas Adsorption ◽  
Coal Gas ◽  
Desorption Isotherms ◽  
Adsorption Desorption

scholarly journals Influence of the synthesis conditions on the characteristics and metal adsorption properties of the 3-(1,4-phenylenediamine)propylsilica xerogel

2005 ◽  
Vol 30 (4) ◽  
pp. 43-49 ◽  
Author(s):  
J. C. P Vaghetti ◽  
J. L. Brasil ◽  
T. M. H Costa ◽  
E. C. Lima ◽  
E.V Benvenutti
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Aqueous Solution ◽  
Adsorption Properties ◽  
Metal Adsorption ◽  
N2 Adsorption ◽  
Organic Precursor ◽  
Synthesis Conditions ◽  
Desorption Isotherms ◽  
Adsorption Desorption

The hybrid 3-(1,4-phenylenediamine)propylsilica xerogel was obtained starting from two different organic precursor quantity (5 and 8 mmol) to 22 mmol of TEOS, in the synthesis. The xerogel samples were characterized by using CHN elemental analysis, N2 adsorption-desorption isotherms, infrared thermal analysis. The xerogel was used as metal sorbent for Cu2+, Cd2+ and Pb2+ in aqueous solution with concentration range of 10-3 to 10-5 mmol l-1. The quantity of organic precursor added in the synthesis influences the characteristics of the xerogel as morphology and thermal stability, as well as the metal adsorption capacity.

scholarly journals Impact of the functionalization onto structure transformation and gas adsorption of MIL-68(In)

2018 ◽  
Vol 5 (12) ◽  
pp. 181378 ◽  
Author(s):  
Lei Wu ◽  
Weifeng Wang ◽  
Rong Liu ◽  
Gang Wu ◽  
Huaxin Chen
Keyword(s):  
Adsorption Capacity ◽  
Surface Area ◽  
Quadrupole Moment ◽  
Gas Adsorption ◽  
Product Formation ◽  
Negative Influence ◽  
Adsorption Enthalpy ◽  
Molar Ratios ◽  
Adsorption Desorption ◽  
The Impact

A series of functionalization –NH 2 , –Br and –NO 2 has been performed on MIL-68(In) material in order to improve the porosity features of the pristine material. The functional groups grafted onto the ligand and the molar ratios of the ingredient indicate a profound influence on product formation. With the incremental amount of metal source, product structures undergo the transformation from MIL-68 to MIL-53 or QMOF-2. The situation is different depending on the variation of the ligands. Gas (N 2 , Ar, H 2 and CO 2 ) adsorption–desorption isotherms were systematically investigated to explore the impact of the functionalization on the porous prototypical framework. Comparison of adsorption behaviour of N 2 and Ar indicates that the polar molecule exhibits striking interaction to N 2 molecule, which has a considerable quadrupole moment. Therefore, as a probe molecule, Ar with no quadrupole moment is more suitable to characterize the surface area with the polar groups. Meanwhile, Ar adsorption result confirms that the negative influence on the surface area stems from the size of the substituting groups. The uptake of H 2 and CO 2 indicates that the introduction of appropriate polar organic groups can effectively enhance the adsorption enthalpy of relative gases and improve the gas adsorption capacity apparently at low pressure. The introduction of –NO 2 is in favour of improving the H 2 adsorption capacity, while the grafted –NH 2 groups can most effectively enhance the CO 2 adsorption capacity.

Binding of lead and copper(II) cations to hemicelluloses of rye bran

1986 ◽  
Vol 51 (10) ◽  
pp. 2250-2258 ◽  
Author(s):  
Rudolf Kohn ◽  
Zdena Hromádková ◽  
Anna Ebringerová
Keyword(s):  
Uronic Acid ◽  
Equilibrium Solution ◽  
Glucuronic Acid ◽  
The Other ◽  
Carboxyl Groups ◽  
Stoichiometric Ratio ◽  
Molar Ratios ◽  
Free Ions ◽  
Uronic Acid Content ◽  
The Relationship

Several fractions of acid hemicelluloses isolated from rye bran were characterized by molar ratios of saccharides (D-Xyl, L-Ara, D-Glc, D-Gal) and 4-O-methyl-D-glucuronic acid and protein content. Binding of Pb2+ and Cu2+ ions to these acid polysaccharides was considered according to function (M)b = f([M2+]f), expressing the relationship between the amount of metal (M)b bound to 1 g of the substance and the concentration of free ions [M2+]f in the equilibrium solution and according to the association degree β of these cations with carboxyl groups of uronic acid at a stoichiometric ratio of both components in the system under investigation. Acid hemicelluloses contained only a very small portion of uronic acid ((COOH) 0.05-0.18 mmol g-1); the model polysaccharide, 4-O-methyl-D-glucurono-D-xylan of beech, was substantially richer in uronic acid content ((COOH) 0.73 mmol g-1). Consequently, the amount of lead and copper bound to acid hemicelluloses is very small ((M)b 0.017-0.025 mmol g-1) at [M2+]f = 0.10 mmol l-1. On the other hand, much greater amount of cations ((M)f 0.09-0.10 mmol g-1) was bound to the glucuronoxylan. The association degree β was like with the majority of samples (β = 0.31-0.38). The amount of lead and copper(II) bound to acid hemicelluloses from rye bran is several times lower than that bound to dietary fiber isolated from vegetables (cabbage, carrot), rich in pectic substances.

scholarly journals A comprehensive analysis of novel disulfide bond introduction site into the constant domain of human Fab

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hitomi Nakamura ◽  
Moeka Yoshikawa ◽  
Naoko Oda-Ueda ◽  
Tadashi Ueda ◽  
Takatoshi Ohkuri
Keyword(s):  
Thermal Stability ◽  
Pichia Pastoris ◽  
Protein Stability ◽  
Disulfide Bond ◽  
Binding Activity ◽  
Comprehensive Analysis ◽  
The Other ◽  
Constant Domain ◽  
Intermolecular Disulfide Bond ◽  
Sds Page

AbstractGenerally, intermolecular disulfide bond contribute to the conformational protein stability. To identify sites where intermolecular disulfide bond can be introduced into the Fab’s constant domain of the therapeutic IgG, Fab mutants were predicted using the MOE software, a molecular simulator, and expressed in Pichia pastoris. SDS-PAGE analysis of the prepared Fab mutants from P. pastoris indicated that among the nine analyzed Fab mutants, the F130C(H):Q124C(L), F174C(H):S176C(L), V177C(H):Q160C(L), F174C(H):S162C(L), F130C(H):S121C(L), and A145C(H):F116C(L) mutants mostly formed intermolecular disulfide bond. All these mutants showed increased thermal stability compared to that of Fab without intermolecular disulfide bond. In the other mutants, the intermolecular disulfide bond could not be completely formed, and the L132C(H):F118C(L) mutant showed only a slight decrease in binding activity and β-helix content, owing to the exertion of adverse intermolecular disulfide bond effects. Thus, our comprehensive analysis reveals that the introduction of intermolecular disulfide bond in the Fab’s constant domain is possible at various locations. These findings provide important insights for accomplishing human Fab stabilization.

scholarly journals Laser THz Emission Spectroscopy of Gas Adsorption-Desorption Dynamics in Tungsten Disulfide Nanosheets

2016 ◽  
Vol 14 (0) ◽  
pp. 78-82 ◽  
Author(s):  
Filchito Renee Bagsican ◽  
Iwao Kawayama ◽  
Hironaru Murakami ◽  
Masayoshi Tonouchi ◽  
Andrew Winchester ◽  
...  
Keyword(s):  
Emission Spectroscopy ◽  
Gas Adsorption ◽  
Tungsten Disulfide ◽  
Adsorption Desorption

CHANGES IN THE THERMAL STABILITY AND ACIDIC CHARACTERISTICS OF HYDROXY-Al-MONTMORILLONITE COMPLEXES FORMED IN THE PRESENCE OF CITRIC ACID

1985 ◽  
Vol 65 (3) ◽  
pp. 519-522 ◽  
Author(s):  
TEE BOON GOH ◽  
P. M. HUANG
Keyword(s):  
Thermal Stability ◽  
Citric Acid ◽  
Organic Carbon ◽  
Organic Acid ◽  
Key Words ◽  
Titratable Acidity ◽  
Structural Water ◽  
Molar Ratios ◽  
Gradual Loss

The thermal stability and acidic characteristics of Al interlayered montmorillonite were affected by citric acid which was present during its formation. Perturbation to the formation of Al interlayers by citric acid resulted in more gradual loss of their structural water in the 430 °C to 520 °C region at initial citric acid/Al molar ratios of 0.1 and 0.5. The data clearly reveal that, besides hydroxy-Al polymers, hydroxy-Al-citrate complexes adsorbed on the surfaces of montmorillonite very substantially contribute to the total and third buffer range titratable acidity of the clay. Key words: Hydroxy-Al-citrate interlayers, smectite, organic acid, DTA, third buffer range, organic carbon

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