Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 5 of 5
Full-Text Articles in Physical Sciences and Mathematics
Friedel-Crafts Alkylation Of Benzene With A Superacid Catalyst, Josh T. Cutright
Friedel-Crafts Alkylation Of Benzene With A Superacid Catalyst, Josh T. Cutright
Undergraduate Honors Theses
Long-chain alkylbenzenes are industrially synthesized precursors to commercial surfactants such as laundry detergent. The currently used catalysts in the processes of their synthesis are corrosive and harmful to the environment. These problems can be avoided utilizing heterogeneous highly acidic catalysts. Solid catalysts do not corrode equipment and are relatively simple to remove from the post-reaction mixture. Phosphotungstic acid (PTA) supported on silica gel could be a possible catalyst due to its high acidity with an estimated pKa ≈ -13. The catalyst PTA-SiO2 was prepared via the sol-gel method to covalently embed it in a silica support. The catalyst was …
Alkylation Of Benzene On Immobilized Phosphotungstic Acid, Kofi Kankam
Alkylation Of Benzene On Immobilized Phosphotungstic Acid, Kofi Kankam
Electronic Theses and Dissertations
Linear alkylbenzenes (LAB) are key intermediates in the synthesis of linear alkylbenzene sulfonate surfactants that are used in the manufacture of detergents. Production of LAB with traditional Lewis acids as catalysts, such as hydrofluoric acid, results in the formation of large amounts of toxic wastes and corrosion of industrial equipment. Phosphotungstic acid (PTA) has gained much attention in recent years as a solid catalyst for various alkylation reactions. This research work aims to develop a novel material based on PTA-containing silica gel, which can effectively catalyze LAB synthesis. Sol-gel synthesis of silica gel in the presence of PTA and tetraethyl …
Immobilization Of Phosphotungstic Acid On Silica Surface For Catalytic Alkylation Of Aromatic Compounds, Anastasia Kuvayskaya
Immobilization Of Phosphotungstic Acid On Silica Surface For Catalytic Alkylation Of Aromatic Compounds, Anastasia Kuvayskaya
Electronic Theses and Dissertations
Superacidic mesoporous materials containing covalently embedded PTA were synthesized by sol-gel method. Tetraethyl orthosilicate (TEOS) and phosphotungstic acid (PTA) were used as precursors in the synthesis, ionic and nonionic surfactants were used as pore-forming agents, the reaction proceeded in acidic media. TEM images revealed mesoporous structure with embedded PTA clusters. FT-IR spectra of obtained materials contained characteristic bands of PTA at 957 cm-1. Synthesized catalysts had high BET surface area and high concentration of acidic sites. Alkylation of 1,3,5-trimethylbenzene by 1-decene demonstrated high catalytic activity. The catalyst obtained with Pluronic P123 as a template was the most effective and resulted …
Functionalized Silica Gel For Adsorption Of Cesium From Solution, Kenneth Marshall Seaton Iii
Functionalized Silica Gel For Adsorption Of Cesium From Solution, Kenneth Marshall Seaton Iii
Electronic Theses and Dissertations
Mesoporous silica gel containing embedded phosphotungstic acid (PTA) was synthesized by sol-gel co-condensation of tetraethyl orthosilicate with PTA in acidic media. The obtained material had high Brunauer-Emmett-Teller Theory (BET) surface area and pore volume. A characteristic band of the Keggin structure of PTA was present in its FT-IR spectrum while its X-ray diffraction patterns were absent. This proved the embedding of PTA on a sub-molecular level and not as a second phase. Acidic sites were determined by neutralization with base in aprotic solvent, followed by titration of the remaining base with an acid. The material demonstrated high adsorption capacity of …
Immobilization Of Heteropolyacids In Silica Gel, Opeyemi Adetola
Immobilization Of Heteropolyacids In Silica Gel, Opeyemi Adetola
Electronic Theses and Dissertations
Silica gels containing incorporated heteropolyacids (HPAs) were synthesized in acidic media by co-condensation of tetraethoxysilane (TEOS) with phosphotungstic or phosphomolybdic acids using sol-gel technique. Effect of the synthesis conditions on their structure and morphology was studied. Yields of modified materials were some lower as compared to non-modified silica gels. All materials were mesoporous but contained micropores in their structures. Presence of bands of Keggin’s structures in FT-IR spectra along with absence of XRD patterns of crystalline HPAs confirmed their fine incorporation into silica network. Particle sizes of modified materials were 800-1100 nm excepting for W-containing sample obtained with trimethylstearylammonium chloride. …