Fermented 2-methyl-1-propanol (isobutanol) can be used directly as a biofuel or can be catalytically dehydrated to 2-methylpropene (isobutylene), which serves as a platform molecule for synthesizing other fuels or chemicals. The dehydration reaction was studied over alumina catalysts to determine the impact of process conditions and model compound impurities from fermentation. No significant impurity effects were observed over short (8 h) timescales and dehydration was demonstrated at high conversion and with high selectivity to isobutylene.