Catalyst Design for Hydrogen Production from Ethanol

To further a sustainable energy future, hydrogen to be used in fuel cell applications is required as an alternative to non-renewable resources. In this thesis, catalysts for hydrogen production from ethanol were designed and characterized to draw correlations between the chemistry and structure of said catalysts and their activity, selectivity, and lifetime during ethanol dehydrogenation. Specifically, Impregnated Support Combustion Synthesis (ISCS) is used as a technique to prepare Ni supported catalysts for hydrogen production. The formation of unsupported metallic Ni catalysts by SCS is studied (Chapter 3). It was determined that the mechanism of metal formation in the combustion front is due to reduction by gases released during the combustion reaction when producing bulk Ni catalysts. In Chapter 4, ISCS is used to prepare Ni supported on alumina pellets to enhance the properties of the catalyst, increasing activity for ethanol decomposition at lower temperatures as compared to the bulk unsupported Ni catalysts. Ni catalysts prepared by ISCS are also supported on ceria and silica powders (Chapter 5) to determine the effect of supports on the activity and selectivity of the catalysts. In-situ techniques are employed to correlate the chemistry and structure of the catalysts near reaction conditions to their performance during reaction. Lastly, the stability towards deactivation of these Ni supported catalysts, as well as newly designed catalysts, is described (Chapter 6). UHV-XPS and TEM images before and after reaction are used to determine the causes of deactivation during ethanol decomposition. It was found that carbon formation heavily affected the catalysts? activity during extended periods of reaction, and to prevent deactivation, a partial encapsulation of the active metal by the support was necessary.