Methanol Dehydration to Dimethyl Ether over  Modified -Al2O3 with Acid, Base and Zeolite (NaA and NaX)

Maria  Ulfah; Hendra Suherman; Melia Laniwati; Subagjo Subagjo

Maria Ulfah Department of Chemical Engineering, Bung Hatta University, Jl. Gajahmada No. 19, Nanggalo Olo, Kampus III Bung Hatta University, Padang , Indonesia
Hendra Suherman Department of Chemical Engineering, Bung Hatta University, Jl. Gajahmada No. 19, Nanggalo Olo, Kampus III Bung Hatta University, Padang , Indonesia
Melia Laniwati Chemical Reaction Engineering & Catalysis Group, Department of Chemical Engineering, Institut Technology Bandung, Jl. Ganesa 10, Bandung, Indonesia
Subagjo Subagjo Chemical Reaction Engineering & Catalysis Group, Department of Chemical Engineering, Institut Technology Bandung, Jl. Ganesa 10, Bandung, Indonesia

Keywords: Dimetyl ether, Methanol dehydration, Modified alumina, Surface acidity, Textural properties

Abstract

The effect of acids, bases, zeolite NaA and zeolite NaX impregnation to g-Al₂O₃ on the catalyst characteristics and activity against methanol dehydration reaction were investigated. The catalyst characteristics include N₂ physisorption, X-ray diffraction (XRD), and temperature-programmed desorption of ammonia (NH₃-TPD) in addition to catalytic dehydration of methanol performed in a micro fixed-bed reactor at 270°C and 1 atm. The results of XRD characterization showed no changes related to the modification of alumina over acids, bases, and zeolite NaA and zeolite NaX. Therefore, the modification did not have any effect on the crystalline structure of alumina. The textural and surface acidity of g-Al₂O₃ changed post addition of acids, bases, zeolite NaA and zeolite NaX. NH₃-TPD analysis results demonstrated that synthesized g-Al₂O₃ has three types of acid sites: weak, medium, and strong; however, the weak acid sites were not observed on alumina catalysts modified phosphate, KOH, zeolite NaA, and zeolite NaX. Furthermore, the concentration of strong acid sites increased in the catalyst containing KOH. The catalytic test results showed that the untreated g-Al₂O₃ catalyst gave prominent activity in dehydration of methanol compared to the treated catalyst following the number and strength of acid sites.

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