The transformation of amorphous aluminum oxide during the catalytic dehydration of aromatic alcohol

A wide application of aluminum oxides in the synthesis of heterogeneous catalysts for petrochemistry and oil refining makes it necessary to reveal factors determining the efficiency of the catalytic systems. However, the literature provides no data concerning the effect produced by the amorphous phase in aluminum oxide catalysts on characteristics of the catalytic reaction. Usually the content of amorphous phase is not categorized; however, its presence may significantly deteriorate the catalyst efficiency. X-ray diffraction analysis, low-temperature nitrogen adsorption, electron microscopy and temperature-programmed desorption of ammonia were used in this work to examine samples of the amorphous aluminum oxide obtained from two different precursors. Catalytic properties of the samples were investigated during the vaporphase dehydration of 1-phenylethanol to styrene. It was shown for the first time that the transformation of amorphous aluminum oxide in the catalytic reaction decreased the conversion of alcohol from 84 (for the fresh catalyst) to 64 % (for the regenerated sample). Crystallization of amorphous aluminum oxide by the high-temperature treatment enhanced the catalytic performance, but it did not reach the desired values due to a considerable deterioration of the textural characteristics and acidic properties of the aluminum oxide surface.