Effect of particle size of gallium containing MFI catalyst on ethanol conversion to aromatics

Abstract

Effect of particle size of gallium containing MFI catalyst on ethanol conversion to aromatics was investigated in this research. Five of MFI zeolite catalysts, having different particle size (1.0, 1.9, 3.2, 4.1 and 6.0 micrometre), were synthesized by hydrothermal treatment with SiO2/Al2O3 ratios of 40. Gallium were contained on these catalysts by ion-exchanged. The obtained products were characterized by XRD, XRF, BET, SEM, NH3-TPD and [superscript 27]Al MAS NMR spectrometer. After these catalysts were pretreated, the results suggest that the small particle size of Ga/MFI catalysts showed a slight decrease in crystallinity, moderate acidity and moderate dealumination of tetrahedral aluminum while the large particle size of Ga/MFI catalysts lost considerable crystallinity, extensive acidity and extensive dealumination. The influence of catalysts on ethanol conversion aromatics were examined three points; gallium affected to the selectivity of aromatics more than acidity, the acidity affected to the selectivity of 1) benzene 2) toluene 3) xylene and the acidity of all Ga/MFI (fresh and pretreated) catalysts was enough to convert ethanol to olefins