Published July 2001
The subject patent claims the use of the mono- or dipotassium salt of silicotungstic acid or phosphotungstic acid as catalyst for the continuous vapor-phase hydration of ethylene to ethanol wherein unreacted ethylene is recycled back to the hydration reaction. Traditional technology uses supported phosphoric acid as the catalyst. Experimental data are provided on the preparation and use of the monopotassium salt of 12-tungstosilicic acid/phosphoric acid (molar ratio (1/0.1) supported on silica.
This review examines use of this catalyst in a world-scale plant producing 600 million lb/yr (272,000 t/yr) of anhydrous ethanol. A process design incorporating the experimental data was developed and capital and production costs for the plant estimated. The design includes the intermediate production of ~190 proof ethanol and final production of anhydrous ethanol via azeotropic distillation with cyclohexane
