Ethanol dehydration over alumina catalysts with phosphorus and noble metal modification

Abstract

The mixture of 1:1 volume ratio of gamma and chi crystalline phase alumina support was prepared via the solvothermal technique using the mixed solution between toluene and 1-butanol. The support was brought to modify with phosphoric acid and noble metal agents. These catalysts were investigated on the effect of both phosphorus loading and types of noble metal on catalytic characteristic and catalytic activity. The catalytic performance was identified through ethanol dehydration reaction in gas phase process at 1 atm and temperature of 200oC to 400oC. The results were found that the phosphorus modification had an effect on catalytic acidity by decreasing the amount of medium to strong acid sites and raised quantity of weak acid sites. The higher amount of weak acid brought the catalysts to demonstrate the higher catalytic activity through the ethanol dehydration to diethyl ether. The mixed phase of alumina supports modified with 5 wt% of phosphorus exhibited the highest catalytic activity among other P-modified alumina catalysts giving the diethyl ether yield of 34.41%. In addition, the different types of noble metal modification were found to have a significant effect on catalytic performance. The 5P/Al2O3 catalyst deposited by palladium showed the highest catalytic activity through all of the studied catalysts reached 57.68% of diethyl ether yield. The highest average yield of diethyl ether of 42.50% was obtained from using Pd5P/Al2O3 catalyst in time on stream system for 10 h. Despite of high diethyl ether yield obtained, both 5P/Al2O3 and Pd5P/Al2O3 catalysts had the lower coke formation when compared to non-modified alumina supports.