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Direct and Postsynthetic Functionalization of Mesoporous B-SBA-15-SO₃H Acid Catalyst and Application to Methyl Propionate Esterification

100%
Erdem B., Azko Ç., Erdem S., Öksüzoğlu R.
Acta Physica Polonica A
|
2017
|
vol. 132
|
issue 3
756-759
EN
Organic functionality can be added to mesoporous silicates in two ways: either by covalent grafting (postsynthetic) of various functional groups onto the channel walls or by incorporating functionalities directly during the synthesis (one-pot). If the grafted catalytically active groups experience similar environments and are isolated from each other, catalysis process is greatly facilitated. For this purpose, boric acid, as boron source, was added into the initial reaction mixture and then acid functionalization was performed by post and direct method. The obtained acid catalysts were tested in the esterification of propionic acid with methanol and the activity of these new materials was compared to that of SBA-15-SO₃H. Boron addition has facilitated the methyl propionate esterification for both postsynthetic and direct functionalized acid catalyst. Boron incorporated and postsynthetic functionalized mesoporous acid catalyst has highly enhanced the esterification reaction, compared to direct functionalized acid catalyst. The post functionalization method seems to be superior to one-pot functionalization method for preparation of mesoporous acid catalysts.
2
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Towards Understanding of Influence of Restricted Geometry on Self-Diffusion in Porous Media

80%
Stankovic I.
Acta Physica Polonica A
|
2009
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vol. 116
|
issue 4
701-704
EN
Novel simulation procedure of self-diffusion through model porous media is presented. The procedure is based on extensive use of molecular dynamic method. The introduced diffusion simulations have a potential to become a valuable design and development tool applications involving transport in porous media, e.g. filters or porous sensors. The porous membranes are created using phase-separating model with high surface tension and its properties are characterized and compared with existing porosimetry measurements and small angle scattering experiments. These membranes are then filled with a gas of diffusing particles. Relations between transport coefficients and material structure are discussed.
3
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Sol-Gel Derived Lanthanide-Substituted Layered Double Hydroxides Mg₃/Al_{1-x}Ln_{x}

70%
Smalenskaite A., Şen S., Salak A., Ferreira M., Beganskiene A., Kareiva A.
Acta Physica Polonica A
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2018
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vol. 133
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issue 4
884-886
EN
Mg/Al/Ln (Ln = Nd, Sm, Eu) layered double hydroxides (LDHs) were synthesized using sol-gel method for the first time to the best our knowledge. The obtained materials were characterized by X-ray diffraction analysis and fluorescence spectroscopy. The phase composition and luminescent properties of these LDHs were investigated and discussed. The Ln³⁺ substitution effects were investigated in the Mg₃Al_{1-x}Ln_{x} LDHs by changing the Ln³⁺ concentration in the metal cation layers up to 10 mol%. It was demonstrated that only Mg₃Al_{1-x}Eu_{x} LDHs showed luminescence properties, however, no any light emission was observed for the Mg₃Al_{1-x}Nd_{x} and Mg₃Al_{1-x}Sm_{x} LDH samples.
4
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Novel Molding Method and Enhanced Cell Homogeneity in the Powder Metallurgical Route for Production of Closed Cell Al-Foam

70%
Erturk A., Sahin T.
Acta Physica Polonica A
|
2017
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vol. 131
|
issue 1
39-42
EN
TiH₂ content, mixing, pressing, different mold filling rate as the factors which affect foaming process on the powder metallurgical route were investigated. TiH₂ was added in the amount of 0.5-1-1.5-2 wt% to adjust the proper amount. Differential scanning calorimetry tests were conducted on the TiH₂ powders in order to obtain optimum hydrogen releasing condition. Aluminum and TiH₂ powders were blended with the different speed-time combination. The mix was compacted at different pressures with the aim of explaining of the oxide layer deformation. An acceptance-rejection criterion was developed and used in pore analysis. Also, the using of a borosilicate glass molding technique are completely original and a new approach.
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