Influence of Structure Type of Al₂O₃ on Dehydration of Methanol for Dimethyl Ether Synthesis

Abstract

This study focused on the effect of alumina properties on the catalytic performance in the dehydration of methanol to synthesize dimethyl ether. The catalysts (γ-Al 2 O 3 and η-Al 2 O 3 ) were prepared from boehmite and bayerite, respectively, via calcination at various temperatures. With heat treatment, the properties of alumina have been changed significantly. Under identical reaction conditions, γ-Al 2 O 3 calcined at 500°C and η-Al 2 O 3 calcined at 600°C showed the highest catalytic activity, because of high acid site density among the same types of alumina. Interestingly, η-Al 2 O 3 showed higher catalytic activity than γ-Al 2 O 3 , although both catalysts possess comparable acidic properties. This means the structure type of alumina is crucial to determine catalytic performance in this reaction.

Effect of precursor on the performance of alumina for the dehydration of methanol to dimethyl ether

“…For all catalysts, the particle size of γ-Al 2 O 3 increased with increasing calcination temperature which is in agreement with Seo et al [27]. The large particle size for the AN120,…”

“…Seo et al [27] studied the influence of structure type of Al 2 O 3 on the dehydration of methanol to dimethyl ether. Catalysts (γ-Al 2 O 3 and η-Al 2 O 3 ) were prepared from boehmite and bayerite, respectively, via calcination at various temperatures and the effect of alumina properties on the catalytic performance evaluated.…”

“…This maximum is less clearly defined than in the case of the AC catalysts. The decrease of activity at calcination temperature of 750 ˚C may be attributed to the structure of η-Al 2 O 3 calcined at 750 °C which partially collapsed resulting in a decrease in acid site density [27] and an associated decrease in catalytic activity.…”

“…Such significant differences in activity between AN catalysts and AC catalysts, may be attributed to the structure γ-Al 2 O 3 which possessed almost hexagonally formed crystallites with an exposed surface of (110) planes preferentially whereas η-Al 2 O 3 possessed relatively large particles, and the preferentially exposed surfaces correspond to the (111) crystallographic planes. [27] Furthermore given the relative difference in activities between the two precursors and their relative similarity in terms of surface area etc., for example, AN550 has higher DME formation rate than AC550 catalyst for all temperature ranges as shown in Figure (8)a and higher DME yield (see Table (1)), this suggests that some poisoning of catalyst sites due to residual chloride may be responsible.…”

Influence of Ionic Liquid as a Template on Preparation of Porous η-Al2O3to DME Synthesis from Methanol

“…It have been known that the moderate acid site strength of alumina could enhance the formation of DME from methanol. 13 In our previous work, 14 η-Al 2 O 3 showed significant performance for methanol dehydration to produce DME. Moreover, it was found that the structure of alumina is more crucial factor than acidity properties to determine catalytic performance.…”