A process for the conversion of an alcohol mixture to make propylene may include introducing into a reactor a stream that includes the alcohol mixture. The alcohol mixture may include 20 to 100 weight percent isobutanol. The process may include contacting the stream with a single catalyst at a temperature above 450° C. in the reactor at conditions effective to dehydrate the isobutanol, forming C4+ olefins, and to catalytically crack the C4+ olefins. The single catalyst may be an acid catalyst adapted to cause both the dehydration and the catalytic cracking. The process may include recovering from the reactor an effluent that includes ethylene, propylene, water, and various hydrocarbons. The process may include fractionating the effluent to produce an ethylene stream, a propylene stream, a fraction of hydrocarbons having 4 carbon atoms or more, and water.