EFFECT OF ALUMINA SUPPORTS ON THE PROPERTIES OF SUPPORTED NICKEL-CATALYSTS

The objective of this study is to compare the properties and performance of a series of alumina supported nickel catalysts where the only variable is the origin of the alumina. Three commercial aluminas were subjected to a battery of characterization techniques including dissolution studies, X-ray diffraction, nickel adsorption, and measurements of the pH of their point of zero charge. Nickel catalysts formed on these supports were characterized by temperature-programmed reduction, temperature-programmed reaction of carbon monoxide, and temperature-programmed surface reaction. The performance of the catalysts was assessed by CO/H-2 methanation studies. The results from the characterization and performance studies demonstrated that two types of nickel can exist on these alumina supports: a surface nickel and an incorporated nickel. The extent of partitioning between these two states is controlled by the dissolution properties of each alumina when in contact with nickel electrolytes at low pH.