Topic
Silica gel
About: Silica gel is a research topic. Over the lifetime, 22313 publications have been published within this topic receiving 325516 citations. The topic is also known as: Amorphous silica & Precipitated amorphous silica.
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TL;DR: In this paper, the effect of temperature and NiO content on the asphaltene uptake by a hybrid nanomaterial composed of nickel oxide nanoparticles supported on a nanoparticulated matrix of silica gel was analyzed.
Abstract: The aim of this study is to analyze the effect of temperature and NiO content on the asphaltene uptake by a hybrid nanomaterial composed of nickel oxide nanoparticles supported on a nanoparticulated matrix of silica gel. The silica gel nanoparticles were synthesized by sol–gel method. The silica-supported nanomaterial was prepared by an incipient wetness technique. At constant temperature, adsorption of asphaltenes onto the hybrid nanomaterials increased with increasing its nickel oxide content. Regardless of the asphaltene concentration, asphaltene uptake by the hybrid nanomaterials decreased with increasing temperature. Experimental data on asphaltene sorption isotherms were adequately adjusted by the Freundlich model. The calculated thermodynamic properties for the sorption of asphaltenes onto the nanoparticulated-materials confirmed the spontaneity and exothermic nature of this process.
83 citations
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TL;DR: In this paper, the adaption of two organic dyes (alizarin red S and phenol red) on mesoporous silica and hybrid gels is investigated.
83 citations
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TL;DR: In this paper, substitutions of substituted benzothiazoles have been synthesized by condensation of o-aminothiophenol and aromatic or aliphatic aldehydes in the presence of silica gel under microwave irradiation (MW) and solvent-free conditions.
83 citations
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TL;DR: In this paper, the catalytic efficiency of the heterogeneous photocatalysts was studied for the oxidation of different benzyl alcohols in water and compared to the analogous homogeneous reactions.
Abstract: Benzyl alcohols are oxidized cleanly and efficiently to the corresponding aldehydes under irradiation using flavin photocatalysts and aerial oxygen as the terminal oxidant in homogeneous aqueous solution. Turnover frequencies (TOF) of more than 800 h⁻¹ and turnover numbers (TON) of up to 68
were obtained. Several flavin photocatalysts with fluorinated or hydrophobic aliphatic chains were immobilized on solid supports like fluorous silica gel, reversed phase silica gel or entrapped in polyethylene pellets. The catalytic efficiency of the heterogeneous photocatalysts was studied for the oxidation of different benzyl alcohols in water and compared to the analogous homogeneous reactions. Removal of the
heterogeneous photocatalyst stops the reaction conversion
immediately, which shows that the immobilized flavin is the catalytically active species. The immobilized catalysts are stable, retain their reactivity if compared to the corresponding homogeneous systems and are easily removed from the reaction mixture and reused. TOF of up to 26 h⁻¹, TON of 280
and up to 3 reaction cycles without loss of activity are possible with the heterogeneous flavin photocatalysts.
83 citations
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TL;DR: In this paper, silylation reactions using liquid and supercritical CO2 as the solvent were performed on both single surface (silicon wafers) and nanoporous (silica gel) silica samples.
Abstract: Silylation reactions using liquid and supercritical CO2 as the solvent were performed on both single surface (silicon wafers) and nanoporous (silica gel) silica samples. The alkylsilyl monolayers formed on single surfaces were characterized by wettability, ellipsometry, and X-ray photoelectron spectroscopy. Modified nanoporous silica samples were analyzed by chemical analysis. A range of different silanes including monochloro-, dichloro-, trichloro-, and dimethylamino-silanes was examined. The results indicate that dense carbon dioxide is a good solvent for silylation reactions, comparable or better than most solvents. Compared with the optimum conditions for silylation at solid−liquid interfaces, reactions in carbon dioxide are faster, although maximum bonding densities are slightly lower.
83 citations