Abstract
The catalytic partial oxidation of ethanol and ethanol-water was investigated over noble metal and metal plus ceria-coated alumina foams at catalyst contact times <10 ms. The effects of catalyst, flow rate, and water addition on selectivity and conversion were examined. Rh–Ce catalysts were the most active and stable. Without water addition, ethanol was converted directly to H 2 with >80% selectivity and >95% conversion with Rh–Ce catalysts. Rh, Pt, Pd, and Rh–Ru produced less H 2, with Pt and Pd producing <50% H 2. Pt, Pd, and Rh also produced more CH 4 and C 2H 4 than Rh–Ce. There was a smaller dependence on flow rate for Rh–Ce catalysts than other catalysts. Variation of a factor of 2 produced small changes in H 2, and lower flow rates produced less CH 4 and C 2H 4. Autothermal operation was achieved at as low as 10 mol% ethanol in water. Adding water to the Rh–Ce catalyzed reactor increased H 2 selectivity and reduced selectivity to CO to <50% due to increased water–gas shift and steam reforming activity. With added water, the selectivity to H 2 exceeds 100%, because both ethanol and water contribute H 2. Also, the total selectivity of all unwanted products, mostly CH 4, is <3% at the H 2 production maximum with water addition.
Published Version
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