In summary, a likely reaction path on alumina catalyst is summarized in Scheme 1. Taking into account that water is a product of reactions 1 and 2 and that reaction temperature is low, it Wang Resin can be supposed that the surface is largely hydroxylated. Thus the active site can be supposed to be constituted by active hydroxyl groups as discussed previously . Thus the first step, denoted as step A in Scheme 1, corresponds to reaction (6), producing ethoxy groups with desorption of water. Later, step B in the scheme gives rise to ethylene through a substantially irreversible elimination mechanism (reaction (9)). As a parallel way, in step C reaction with gas phase ethanol gives rise to diethyl ether in a reversible way. In fact, diethyl ether adsorption can crack with the sequence step –C, step –B producing ethylene too. As said, step B is faster than step C at high temperature and conversion while the reverse is true at lower temperature and conversion. In the case of zeolite catalyst, the scheme of ethanol decomposition is essentially the same.