-Sulfur Deactivation of Reforming Catalysts-
Joseph Mayne and Johannes Schwank
Effect of thiophene, a common sulfur containing
contaminent in gasoline, on the isooctane
reforming activity of Ni based catalysts
Hydrogen as an energy carrier has received extensive attention in the spheres of policy and public debate. The electrochemical conversion of hydrogen gas is an efficient and carbon-emission free process. While the possibilities for a future infrastructure based on hydrogen are theorized and debated there are already opportunities for hydrogen to make a significant impact in certain niche roles. Indeed, there exists interest from both the federally supported research community and private industry to pursue flexible fuel reformer technology to produce hydrogen from feed streams of a diverse nature. Examples of feed streams range from methane rich streams (natural gas or gasification products) to heavier liquid fuels (gasoline, jet fuel and diesel).
In the development of reformer technology it is necessary to tackle the main impediments to catalytic fuel reformers. For example, nickel based reforming catalysts are prone to activity loss over time due to the blockage of active sites by contaminants such as sulfur. We are actively seeking to understand how different types of sulfur interact with and behave in the complex reforming environment. It is our belief that the further understanding of this relationship will lead to the development of more sulfur tolerant reforming technologies.
We are currently interested in a special formulation of nickel catalysts on a ceria-zirconia support. This catalyst has shown promise for the reforming of model liquid feeds using a process known as autothermal reforming. Autothermal reforming compromises the heat transfer demands of steam reforming and the lower hydrogen production of partial oxidation. However, this reaction approach offers a complicated system of thermal and redox gradients. We are interested in how different types of sulfur contaminants behave under these different environments. We also seek to understand how the problems posed by sulfur interplay with other known issues of reforming catalysis, such as carbon formation and catalyst degradation.