Production of linear alpha-olefin 1-octene via dehydration of 1-octanol over Al2O3 catalyst

Abstract

The linear alpha-olefin 1-octene was produced via the dehydration of 1-octanol over Al2O3 catalysts. The effect of calcination temperature on the characteristics of an Al2O3 catalyst and its activity in the dehydration of 1-octanol to 1-octene was investigated. Al2O3 catalysts calcined at various temperatures (250, 500, 750, 1000 degrees C) were evaluated at 300-400 degrees C with a liquid hourly space velocity (LHSV) of 7-56 h(-1). XRD, BET, Al-27-NMR, Py-FTIR, and NH3-TPD analyses indicated that the calcination temperature affected the crystal phase, surface area, occupancy of the coordinated Al3+ ion, and acidic properties of Al2O3 catalysts. Upon calcination at temperatures > 750 degrees C, the surface area of Al2O3 catalysts reduced due to gamma-Al2O3 to theta-Al2O3 phase transition. The changes in the crystal phase decreased the surface area, which correlated to the acidity of the Al2O3 catalyst. The distribution of unsaturated Al3+ ions acing as LAS on the catalyst surface increased with increasing calcination temperature, but decreased above 750 degrees C calcination temperature due to the diminishing surface area. The Al2O3 catalyst calcined at 500 degrees C showed the highest 1-octanol conversion in the dehydration of 1-octanol. High 1-octene selectivity was maintained while the isomer ratio decreased at a high LHSV of 56 h(-1).