Author

Agus Haryanto

Advisor

Fernando, D. Sandun

Committee Member

Pordesimo, Lester

Committee Member

Steele, H. Phillip

Committee Member

Srinivasan, Radhakrisnan

Committee Member

To, S.D. Filip

Date of Degree

5-1-2008

Document Type

Dissertation - Open Access

Department

Department of Agricultural and Biological Engineering

Abstract

The progress in fuel cell technology has resulted in an increased interest towards hydrogen fuel. Consequently, water gas shift reaction has found a renewed significance. Even though iron- and copper-based catalysts have been used for water gas shift reaction for decades, the catalysts are not strong enough to bring carbon monoxide concentration to a level tolerable for a fuel cell working at low temperatures. This study is focused on hydrogen production from water gas shift reaction using a nickel catalyst. Literature review revealed that nickel is one of the promising catalysts for water gas shift reaction. A thermodynamic analysis proved that exothermic water gas shift reaction is thermodynamically favorable at low temperatures but kinetically limited, and vice versa at higher temperatures. Initial experiments using 12 catalysts supported over monolith alumina revealed that nickel supported on ceria-promoted monolith alumina (Ni/CeO2-Al2O3) performed best, especially at 500oC. At this temperature and steam flowrates of 0.1-0.5 ml/min, the nickel catalyst had an activity of 94-99%, H2 yield of 55-61 vol.%, and H2 selectivity of 77-99%. A second set of experiments examined nine nickel based catalysts using different supports (mostly in powder form) which also demonstrated that Ni/CeO2-Al2O3 is the most promising catalyst for high temperature (450oC) water gas shift reaction. When nickel loading was varied from 1 to 8% (w/w), it was apparent that the catalyst performance increased with the nickel loading. Powder alumina resulted in better catalysis than monolith alumina. In this experiment, it was evident that the presence of minor amounts (1% (w/w) of the nickel loading) of a dopant material that included cobalt, chromium, molybdenum, or ruthenium affected the catalytic activity of the primary catalyst. The addition of cobalt or chromium resulted in positive effect on the performance of Ni/CeO2-Al2O3 catalyst. There was no appreciable effect due to the addition of ruthenium, and there was negative effect owing to the presence of molybdenum. Undoped, cobalt-doped, or chromium-doped Ni/CeO2-Al2O3 catalyst performed much better for water gas shift reaction at 450oC than that of a commercial (control) catalyst. A kinetic study revealed that the activation energy of water gas shift reaction over Ni/CeO2-Al2O3 was to be 104.5 kJ/mol.

URI

https://hdl.handle.net/11668/15316

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