Catalytic dehydration of methanol to dimethyl ether (DME) over solid-acid catalysts

A series of solid-acid catalysts with different components contents were prepared by coprecipitation (sol-gel) method. These samples comprised gamma-alumina and modified gamma-Al2O3 with silica. The effects of silica various contents have been investigated on purpose to determine an optimum one. Dehydration of methanol to dimethyl ether (DME) on solid-acid catalysts was studied in a fixed-bed flow reactor at a temperature of 300 degreesC under atmospheric pressure and a GHSV of 15,600 h(-1), The catalysts have been characterized using BET, TGA, XRD, NH3-TPD and elemental analysis techniques and also the results are reported. According to the experimental results, the pure gamma-Al2O3 catalyst shown a good catalytic activity, but this sample undergoes a fairly rapid and irreversible deactivation. Silica-modified catalysts have shown better performance compared to the untreated gamma-Al2O3. It was found that surface areas increase with increasing in the silica loading at aluminosilicate catalysts. Also, by modifying alumina with silica, it was observed that the surface acidity of aluminosilicate catalysts increased with increasing in silica loading. The sample with 6 wt% silica loading has exhibited the best conversion without any by-product. (C) 2004 Elsevier B.V. All rights reserved.