Comparison of Microporous/Mesoporous and Microporous HZSM-5 as Catalyst for Friedel-Crafts Alkylation of Toluene with Ethene
Artikel i vetenskaplig tidskrift, 2014
In this work we investigated the effect of mesopores in a standard zeolite used as a catalyst for Friedel-Crafts alkylation of toluene with ethene. A cationic polymer was used for templating mesopores in a microporous ZSM-5 framework. The mesopore-containing zeolite was compared with a regular zeolite with only micropores with respect to conversion, yield and selectivity. The two NaZSM-5 materials were prepared with the same Si/Al molar ratio and diffuse reflection infrared Fourier transform spectroscopy (DRIFT-FTIR) confirmed that the acidity of the ion-exchanged forms (HZSM-5) were identical. Scanning electron microscopy (SEM) and dynamic light scattering (DLS) were used to determine the particle size of the zeolites, which was similar for the two HZSM-5 materials and nitrogen sorption was used to determine the surface area and pore size distribution. X-ray diffraction (XRD) analysis displayed typical crystalline diffraction patterns for the ZSM-5 framework for both the microporous/mesoporous and the microporous ZSM-5 materials. The results from catalytic testing show an increase in the overall conversion of toluene for the zeolite that contains mesopores. Furthermore, a higher product yield (C 9 ) is obtained for this catalyst. The increase in yield and conversion is most likely due to the mesopores; however, incorporation of mesopores in the microporous ZSM-5 framework gives only minor effects on selectivity with respect to mono- vs. dialkylation, and ortho:meta:para ratio. Consequently, this work shows that the presence of mesopores in a microporous ZSM-5 framework is beneficial for the reaction in terms of conversion of starting material and reaction yield but does not markedly affect the product composition. © 2014 the Partner Organisations.