Abstract: A reactor design and configuration and a process for the catalytic dehydration of ethanol to ethylene where the reactor train is comprised of a multi-stage single reactor vessel or multiple reactor vessels wherein each stage and/or vessel has different length, internal diameter, and volume than the other stages and/or vessels and in addition the stages and/or reactor vessels are connected in series arrangement, preferably used with an improved means of introducing the ethanol feedstock and a heat carrying inert gas to the improved reactor train. The inert gas is heated in a separate furnace from the ethanol feed and then injected into the ethanol feed to supply the heat of reaction.