274342 Spectroscopic Characterization of Sulfur Poisoning and Regeneration for Ni-Based Biomass Conditioning Catalysts

Wednesday, October 31, 2012: 4:35 PM
315 (Convention Center )
John Kuhn1, Matthew M. Yung2, Kimberly A. Magrini-Bair2 and Singfoong Cheah2, (1)Chemical and Biomedical Engineering, University of South Florida, Tampa, FL, (2)National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO

Direct evidence of transformation of sulfur species from sulfides to sulfates was observed on a a Ni-Mg-K/Al2O3 catalyst used in a pilot-scale study to condition biomass-derived syngas created from oak gasification.  This catalyst was tested over multiple reaction/regeneration cycles.  Catalyst samples were collected throughout the study at various conditions and were characterized by sulfur K-edge XANES, TPR, and XRD.  The pilot-scale regeneration consisted of steaming + air followed by H2 reduction and, for comparison, a bench-scale regeneration process of steaming followed by H2 reduction was performed.  Post-reaction samples showed the presence of sulfides arising from H2S poisoning of metallic nickel sites.  Although gaseous sulfur species were observed to leave the catalyst bed during regeneration,  the regeneration of the post-reaction catalysts using both the steam and steam + air procedures led to a transformation of sulfur species from sulfides to sulfates.  The subsequent H2 reduction led to a partial reduction of sulfates back to sulfides.  A proposed reaction sequence is presented.  This demonstrates the importance of regeneration protocol to effectively regenerate catalysts to recovery activity and recommended strategies are discussed.

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See more of this Session: Catalyst Deactivation I
See more of this Group/Topical: Catalysis and Reaction Engineering Division