Synthesis and Characterization of Nano-Sized Pt/HZSM–5 Catalyst for Application in the Xylene Isomerization Process

Abstract

The xylene isomerization is a well-established process in the aromatic-based petrochemical complex. This process aims to convert ethylbenzene (EB), meta- and ortho-xylene to para-xylene (PX). Active metal such as platinum (Pt) on the zeolite support is a commonly used catalyst for isomerization reactions. Different catalysts with different acidic strength of zeolite (Si/Al ratios = 32, 50, and 150) are synthesized in this study. The physical and chemical properties of the synthesized catalysts are characterized using X-ray diffraction (XRD), inductively coupled plasma (ICP), and Brunauer, Emmett, and Teller (BET) surface area analyses. Then, the effect of catalyst types and operating parameters such as temperature (370, 375, 380, and 385 °C), hydrogen partial pressure (2.4, 2.6, 2.8, and 3.0), and weight hourly space velocity (3.2, 3.4, 3.8 and 4.1 h−1) investigated on the xylene isomerization process. Indeed, the variation of EB conversion, xylene loss, and the ratio of PX produced to the PX in equilibrium condition (PXATE) by these influential factors is experimentally monitored in a laboratory-scale xylene isomerization reactor. Results show that the catalyst with a small Si/Al ratio of 32 has higher acidic strength and provides the best isomerization performance. Moreover, the temperatures of 375 °C, hydrogen partial pressure (H2/hydrocarbon) of 2.6, and weight hourly space velocity (WHSV) of 3.5 h−1 are the optimum operating conditions for the xylene isomerization process.