MECHANISM AND KINETICS OF THE ACID-CATALYZED FORMATION OF ETHENE AND DIETHYL-ETHER FROM ETHANOL IN SUPERCRITICAL WATER

Ethene and diethyl ether are the only reaction products of the acid-catalyzed decomposition of ethanol in water at 385-degrees-C (T(r) = 1.02) and 34.5 MPa (P(r) = 1.56). The speed and high selectivity of this reaction create possibilities for farmers to convert fermentation beer directly to ethene at high pressure without prior distillation of the beer. This paper presents a kinetic model of the dehydration chemistry, which can be used for reactor design and scaleup. Ethene formation is kinetically consistent with E2 mechanisms involving protonated ethanol and protonated diethyl ether. Diethyl ether formation is kinetically consistent with an S(N)2 mechanism involving ethanol and protonated ethanol, operating simultaneously with an Ad(E)3 mechanism involving ethanol, ethene, and acid.