Transformation of Amorphous Aluminum Oxide in the Catalytic Dehydration of Aromatic Alcohol

Abstract

The widespread use of aluminum oxides to synthesize heterogeneous catalysts in petroleum chemistry and oil refining makes it necessary to determine the factors that influence the efficiency of catalytic systems. However, there have been no studies on the effect of amorphous aluminum oxide in aluminum oxide catalysts on the characteristics of a catalytic reaction. The amount of amorphous aluminum hydroxides and oxides is generally not certified, but they can considerably worsen the performance of a catalyst. Amorphous aluminum oxide samples obtained from two different precursors are studied in this work via X-ray phase analysis, low-temperature nitrogen adsorption, electron microscopy, and thermally programmed desorption of ammonia. The catalytic properties of the samples are studied in the vapor phase dehydration of 1-phenylethanol to styrene. It is shown for the first time that the transformation of amorphous aluminum oxide during the catalytic reaction lowers the conversion of alcohol from 84 (for a fresh catalyst) to 64% (for a regenerated sample). The crystallization of amorphous aluminum oxide through high temperature treatment contributes to an increase in catalytic indicators. However, they do not reach the required values because of a strong drop in the textural characteristics and acidic properties of an aluminum oxide surface.