The catalytic performance of γ-Al2O3/red clay as a highly active, selective, and stable catalyst for methanol dehydration to dimethyl ether at competitive low reaction temperature

Abstract

This study aims to a more environment eco-friendly approach for producing dimethyl ether (DME), as an alternative fuel, through the dehydration of methanol. The method involves utilizing Egyptian natural red clay (ERC) that has been modified with various percentages of γ-Al2O3 (ranging from 3 to 30 wt%) as catalysts. The most active catalyst (10 % γ-Al2O3/ERC) was then modified with varying HCl percentages (3–7 wt%). The synthesized catalysts properties were examined by various techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2-sorption analysis, and transmission electron microscopy (TEM). The surface acidity of the catalysts was assessed using two methods: dehydration of isopropyl alcohol and chemisorption of pyridine and 2,6-dimethyl pyridine. The results of the catalytic activity study reflected that the treatment of ERC by HCl and γ-Al2O3 improved its activity toward DME production. Specifically, the 5 % HCl/10 % γ-Al2O3/ERC catalyst displayed outstanding activity, achieving conversion value of 90 % with 100 % selectivity to DME at 200 °C. Furthermore, this catalyst demonstrated long-term stability, as it maintained its performance over one week without deactivation. Acidity, and the textural characteristics were identified as the key factors contributing to the remarkable improvement in catalytic activity.