Project Title

Synthesis of Long-chain Alkylbenzenes on Superacidic Catalysts Containing Embedded Phosphotungstic Acid

Authors' Affiliations

Anastasia Kuvayskaya, Department of Chemistry, College of Arts and Sciences, East Tennessee State University, Johnson City, TN. Saul Garcia, Department of Chemistry, College of Arts and Sciences, East Tennessee State University, Johnson City, TN. Aleksey Vasiliev, Department of Chemistry, College of Arts and Sciences, East Tennessee State University, Johnson City, TN.

Location

BEECH MTN. ROOM 120

Start Date

4-12-2019 2:20 PM

End Date

4-12-2019 2:35 PM

Faculty Sponsor’s Department

Chemistry

Name of Project's Faculty Sponsor

Dr. Aleksey Vasiliev

Type

Oral Presentation

Classification of First Author

Graduate Student-Master’s

Project's Category

Organic Chemistry

Abstract Text

Heteropolyacids (HPAs), such as phosphotungstic acid (PTA) and phosphomolybdic acid (PMA), with the Keggin structure are well known as solid superacids with estimated pKa of -13. High acidity of HPAs enabled their use as highly active homogeneous catalysts. However, homogeneous catalysis has many drawbacks, e.g. difficult and expensive separation of the used catalyst from the reaction mixture and its recycling. Application of pure HPAs in heterogeneous catalysis is limited by their low surface area and solubility in polar solvents. For increasing their surface area, HPAs should be immobilized on solid support. The objective of this work is the development of an active and stable HPA-containing catalyst for synthesis of long chain alkylbenzenes, which are essential precursors in the manufacture of surfactants. To prevent leachability of HPA from the support, it was covalently bonded into the silica matrix via Si‑O‑W bridges. The catalysts were obtained by co-condensation of tetraethoxysilane (TEOS) with PTA using sol-gel method in the presence of various surfactants as pore-forming agents. The synthesis was conducted by simultaneous addition of 20% HCl and ethanol solution of a mixture of TEOS and PTA to a solution of a surfactant. The reaction mixture was refluxed for 24 h. The obtained product was filtered, washed, air-dried, and calcined for total removal of a surfactant from pores. Use of Pluronic P123 as a non-ionic pore-forming agent produced the most acidic material. The synthesized mesoporous materials were tested as heterogeneous catalysts in liquid-phase alkylation of mesitylene by long-chain alkenes. They demonstrated higher activity than well-known zeolite HY. The analysis of catalyst recovered after the alkylation indicated no PTA leaching from silica matrix. Obtained superacidic mesoporous materials can potentially replace hazardous liquid Lewis acids currently used for long-chain alkylbenzene synthesis in petrochemical industry.

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Apr 12th, 2:20 PM Apr 12th, 2:35 PM

Synthesis of Long-chain Alkylbenzenes on Superacidic Catalysts Containing Embedded Phosphotungstic Acid

BEECH MTN. ROOM 120

Heteropolyacids (HPAs), such as phosphotungstic acid (PTA) and phosphomolybdic acid (PMA), with the Keggin structure are well known as solid superacids with estimated pKa of -13. High acidity of HPAs enabled their use as highly active homogeneous catalysts. However, homogeneous catalysis has many drawbacks, e.g. difficult and expensive separation of the used catalyst from the reaction mixture and its recycling. Application of pure HPAs in heterogeneous catalysis is limited by their low surface area and solubility in polar solvents. For increasing their surface area, HPAs should be immobilized on solid support. The objective of this work is the development of an active and stable HPA-containing catalyst for synthesis of long chain alkylbenzenes, which are essential precursors in the manufacture of surfactants. To prevent leachability of HPA from the support, it was covalently bonded into the silica matrix via Si‑O‑W bridges. The catalysts were obtained by co-condensation of tetraethoxysilane (TEOS) with PTA using sol-gel method in the presence of various surfactants as pore-forming agents. The synthesis was conducted by simultaneous addition of 20% HCl and ethanol solution of a mixture of TEOS and PTA to a solution of a surfactant. The reaction mixture was refluxed for 24 h. The obtained product was filtered, washed, air-dried, and calcined for total removal of a surfactant from pores. Use of Pluronic P123 as a non-ionic pore-forming agent produced the most acidic material. The synthesized mesoporous materials were tested as heterogeneous catalysts in liquid-phase alkylation of mesitylene by long-chain alkenes. They demonstrated higher activity than well-known zeolite HY. The analysis of catalyst recovered after the alkylation indicated no PTA leaching from silica matrix. Obtained superacidic mesoporous materials can potentially replace hazardous liquid Lewis acids currently used for long-chain alkylbenzene synthesis in petrochemical industry.