Synthesis, characterization and kinetics of AlCl3 supported on silica superacid catalysts for the formation of linear alkylbenzenes

Abstract

The solid superacid catalysts were synthesized by loading AlCl3 on silica gel for benzene alkylation. The prepared catalysts were characterized by various techniques such as BET, FT-IR, MAS-NMR and scanning electron microscopy. The Hammett acidity function (Ho) was used to determine the acid strength of the solid catalysts by employing various Hammett indicators. These catalysts were found to be highly active for benzene alkylation with 1-dodecene. The catalyst prepared by the wet impregnation technique showed *33% selectivity of 2-LAB and AlCl3 vapor treated silica gel catalyst (SG-AlCl3v) showed *45% selectivity of 2-LAB. The FT-IR spectra of the SG-AlCl3v catalyst showed equal number of Bronsted and Lewis acidic sites. The life of SG-AlCl3v catalyst was evaluated in a packed bed reactor and was found to be *300 h for benzene alkylation with 1-dodecene. The 27 Al MAS-NMR of SG-AlCl3v catalyst showed a band at 96.578 ppm, which is attributed to 4-coordinated Al species (2O, 2Cl). The Ho of SG-AlCl3v catalyst was found in the range of -12.70 ( Ho ( 13.16, indicates the superacidic nature. A nonlinear optimization algorithm was developed in MATLAB 7.4.0 and used to determine the kinetic parameters of the benzene alkylation with 1 dodecene in presence of SG-AlCl3v catalyst. The concentrations of the products predicted by the model was found in good agreement with experiments.