Microporosity in Silica Synthesized by the Sol-Gel Method. Adsorption of Nitrogen at 76 K

Hernández, Miguel Ángel; Velasco, José A.; Corona, L.; Asomoza, M.; Solís, S.; Rojas, Fernando; Lara, V.H.

doi:10.1007/978-1-4615-0449-8_12

Cited by 2 publications

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“…As mentioned before, a macroporous silica (α-SiO 2 , i.e., α-quartz) was selected as the adsorbent of reference that is needed to perform the α S plot method. The detailed texture properties and microporosity extent of the samples under study have been reported elsewhere …”

Section: Methodsmentioning

confidence: 99%

Adsorption of Benzene, Toluene, and p-Xylene on Microporous SiO₂

Hernández¹,

Velasco²,

Asomoza³

et al. 2004

Ind. Eng. Chem. Res.

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Adsorption isotherms of aromatic BTX (benzene, toluene, and p-xylene) hydrocarbons on pure and Ag-doped SiO 2 microporous substrates synthesized by the sol-gel procedure have been measured by the gas chromatographic technique at several temperatures in the range between 423 and 573 K. Both Langmuir and Dubinin adsorption models can reasonably fit every set of BTX adsorption data at all temperatures. The uptake degree of these hydrocarbon adsorptives on both SiO 2 and Ag/SiO 2 microporous substrates is temperature-dependent. Additionally, the degrees of interaction of BTX molecules with SiO 2 and Ag/SiO 2 microporous walls have been investigated by evaluation of the corresponding isosteric heats of adsorption (q st ) by means of a Clausius-Clapeyron-type equation. The isosteric heats of adsorption of BTX hydrocarbons at different adsorbate loadings have been inferred from the adsorption isotherms and found to follow the decreasing sequence q st (benzene) < q st (toluene) < q st (p-xylene). Isosteric heats of adsorption of BTX compounds on SiO 2 microporous substrates have been found, in general, to increase with an increase in the adsorbate loading as a consequence of the cohesive interactions between adsorbate molecules. Addition of Ag atoms to the SiO 2 structure helps to homogenize the magnitudes of the isosteric heats of adsorption of the BTX compounds.

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Section: Methodsmentioning

confidence: 99%