A kinetic model for the transformation of aqueous ethanol into hydrocarbons on a HZSM-5 zeolite has been proposed for the 623−723 K range on the basis of experiments carried out in an isothermal fixed-bed reactor with feeds of ethene, ethanol−water mixtures of different mass ratios, and diethyl ether. The kinetic model is of interest for directly upgrading the liquid product obtained by the fermentation of carbohydrate wastes. It is based on the latest progress made in the catalytic transformation of methanol and quantifies the attenuating effect of water in the reaction medium in all the steps of the kinetic scheme.

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With the aim of determining the possibilities of directly upgrading the liquid obtained from carbohydrate fermentation, the effect of operating conditions (temperature, space time, water content in the feed) has been studied in the catalytic transformation of aqueous ethanol into hydrocarbons on an HZSM-5 zeolite in an isothermal ®xed bed reactor. Special attention has been paid to the effect of water content on the yield, product distribution and catalyst deactivation. Although deactivation by coke decreases as the water content is increased, this content must be limited at 450°C and higher temperatures in order to avoid irreversible deactivation of the catalyst by dealumination.

When methanol is converted to olefins on a SAPO‐34 catalyst between 350 and 425°C, there is a rapid initial formation of coke, followed by a slower rate of coke deposition. The rate of coke formation decreases with increasing temperature, and with progression through the catalyst bed. The coke completely blocks the internal channels of the SAPO‐34 crystals and subsequently blocks the mesopores (intercrystalline and those of the bentonite). Coke deposition mainly blocks sites of acidic strength above 175 kJ mol−1. The presence of water in the feed lessens coke formation, either by converting Lewis to Brønsted sites or by competing for surface sites with coke precursors. © 1999 Society of Chemical Industry

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