The conversion of ethanol and the selectivities of ethylene and diethyl-ether over catalysts are plotted in Fig. 8, as a function of space velocity in the fixed bed reactor. The WHSV varied from 2 h1 to 30 h1. The results in Fig. 8 indicated that the ethanol conversion and the ethylene selectivity decreased with rising space velocities but the selectivity of diethyl-ether behaved in the opposite way.