Surface Properties of Sepiolite from Amboseli, Tanzania, and Its Catalytic Activity for Ethanol Decomposition

Abstract

Abstract The catalytic activity of sepiolite from Amboseli, Tanzania, for the dehydration and dehydrogenation of ethanol at 150°–300°C has been studied using a flow reactor. Both reactions occur, but the catalyst activity decreases with use. The products include water, carbon dioxide, ethene, ethanal (acetaldehyde), diethyl ether, but-1,3-diene, but-2-enal (crotonaldehyde), and an unidentified aromatic compound. The proportions change with temperature, the dehydrogenation reaction being favored at the higher temperatures. The BET surface areas of the sepiolite are 316 m 2 /g (nitrogen adsorption at — 197°C) and 212 m 2 /g (ethanol vapor adsorption at 25°C, assuming a molecular cross-sectional area of 24.6 Å 2 ), indicating a possible greater penetration of pores and channels by nitrogen compared with ethanol vapor under these conditions. The pore-size distribution reveals that approximately 55% of the surface area measured by nitrogen adsorption is contributed by micropores.