The objective of this work was to develop a low-waste catalytic synthesis of long-chain alkylbenzenes, which are important intermediates in the manufacture of anionic surfactants. Currently, they are produced by Friedel-Crafts alkylation of benzene using Lewis acids. This approach poses a serious threat to the environment due to generation of large volume of toxic waste. This problem was solved by the use of phosphotungstic acid (PTA) covalently immobilized on the surface of silica gel. PTA is a well-known catalytically active superacid with pKa ≈ -13. Superacidic catalysts were synthesized by co-condensation of tetraethyl orthosilicate with PTA in acidic media. Various surfactants were used as pore-forming agents. FT-IR spectra of the solid products contained characteristic band of PTA. TEM images revealed mesoporous structure of the catalysts and the presence of embedded PTA clusters. Mesoporous materials had high BET surface area and high concentration of easily accessible acidic catalytic sites. Obtained catalysts were successfully tested in liquid-phase alkylation of benzene and 1,3,5-trimethylbenzene by alkenes at various temperatures. The catalyst synthesized with Pluronic P123 as a template demonstrated the highest activity in the conversion of alkenes into alkylbenzenes. High thermal and chemical stability of the obtained mesoporous materials also enabled their recyclability. Catalysts remained active during three subsequent cycles of alkylation.

Alkylation of aromatic compounds by alkenes on superacidic mesoporous catalysts

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.