Coated HZSM‐5 catalyst with aluminophosphate for methanol dehydration to produce dimethyl ether reaction

Abstract

The precipitation method was used to modify HZSM-5 by coating it with aluminophosphate at P/Al molar ratios of 0.3, 0.8, 1.2, and 1.5. These catalysts were characterized by X-ray diffraction, NH 3 -temperature-programmed desorption, Brunauer-Emmett-Teller, Fourier transform infrared, Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES) and scanning electron microscopy and evaluated as catalysts for the methanol dehydration reaction. The ZALPO0.8 catalyst achieved 86% conversion, which was the highest conversion till 315°C. It was found that primary benefits of AlPO modification were that it tended to retard the activity of the highly active acid sites, which promote dimethyl ether decomposition and led to decrease in the apparent activation energy. EXPERIMENTAL Starting materialsThe starting materials with special reference to previous works [14][15][16][17][18][19] are ANN [ANN; Al (NO 3 ) 3 .9H 2 O, extra pure, Merck], ortho-phosphoric acid [H 3 PO 4 , 85 wt%, analysis grade, Merck], and HZSM-5[SiO 2 /Al 2 O 3 = 67.6, ZEOCHEM].