Density functional theory study of adsorption and dissociation of contaminants on zinc orthotitanate

FUEL 86

J. Karl Johnson, karlj@pitt.edu, Department of Chemical Engineering, University of Pittsburgh and National Energy Technology Laboratory, 1242 Benedum Hall, Pittsburgh, PA 15261, Rees B. Rankin, Department of Chemical and Petroleum Engineering, University of Pittsburgh, Benedum Hall, University of Pittsburgh, Pittsburgh, PA 15261, Shiqiang Hao, shiqiang@andrew.cmu.edu, Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, and David S. Sholl, david.sholl@chbe.gatech.edu, School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332.
Integrated Gas Combined Cycle (IGCC) technology provides a method to produce electricity from coal in a clean, efficient way. One of the first steps in the IGCC process is the production of syngas from coal, which must be cleaned before being used in a gas turbine. Syngas is contaminated with H2S, AsH3, H2Se, and other species. A low cost high uptake sorbent is needed to capture these contaminants. Zinc orthotitanate, Zn2TiO4, ('ZTO') has shown potential for removing multiple contaminants from fuel gas streams.

We have used first principles density functional theory (DFT) calculations to examine the dissociative adsorption of H2S, AsH3, and H2Se on the ZTO(010) surface. We first calculated the low energy bulk structures of ZTO with DFT and a cluster expansion method, since the exact bulk structure of ZTO was unknown. Next we analyzed the various low index surfaces of ZTO and found that the ZTO(010) surface has a substantially lower energy of formation than other surfaces we examined. Finally, we have used the nudged elastic band method implemented in DFT to probe the decomposition pathways of various contaminants on the ZTO(010) surface.

 

Mercury and Other Trace Elements in Fuel: Emissions and Control
8:30 AM-11:45 AM, Monday, April 7, 2008 Morial Convention Center -- Rm. 238, Oral

Division of Fuel Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008