The present invention is a process for dehydrating an
alcohol to prepare a corresponding olefin, comprising:(a) providing a composition (A) comprising at least an
alcohol having at least 2 carbon atoms, optionally water, optionally an
inert component, in a
dehydration unit,(b) placing the composition (A) into contact with an acidic catalyst in a
reaction zone of said
dehydration unit at conditions effective to dehydrate at least a portion of the
alcohol to make a corresponding olefin,(c) recovering from said
dehydration unit an
effluent (B) comprising:at least an olefin,water,undesired by-products including aldehydes and light products,optionally unconverted alcohol(s),optionally the
inert component,wherein,said composition (A)—providing step (a) comprises adding an effective amount of one or more
sulfur containing compound capable to reduce the undesired by-products by comparison with a non introduction of such
sulfur containing compound.The component introduced at step (a) can be chosen from the group consisting of thiols, sulfides, disulfides.