Enhanced Activity and Stability of Gold/Ceria-Titania for the Low-Temperature Water-Gas Shift Reaction.

James H Carter,Simon J Freakley,Graham J Hutchings,Stan Golunski,Parag M Shah,David J Morgan,Ewa Nowicka

doi:10.3389/fchem.2019.00443

James H Carter, Simon J Freakley + Show 5 more

Open Access

https://doi.org/10.3389/fchem.2019.00443

Copy DOI

Journal: Frontiers in Chemistry	Publication Date: Jun 14, 2019
Citations: 14	License type: CC BY 4.0

Affiliation: Cardiff University, University of Bath

Abstract

Gold supported on ceria-zirconia is one of the most active low temperature water-gas shift catalysts reported to date but rapid deactivation occurs under reaction conditions. In this study, ceria-titania was evaluated as an alternative catalyst support. Materials of different Ce:Ti compositions were synthesized using a sol-gel methodology and gold was supported onto these using a deposition-precipitation method. They were then investigated as catalysts for the low-temperature water-gas shift reaction. Au/Ce0.2Ti0.8O2 exhibited superior activity and stability to a highly active, previously reported gold catalyst supported on ceria-zirconia. High activity and stability was found to be related to the support comprising a high number of oxygen defect sites and a high specific surface area. These properties were conducive to forming a highly active catalyst with well-dispersed Au species.

Highlights

The low-temperature water-gas shift (LTS) reaction has been extensively studied in recent years as a means of upgrading reformate by removing CO and generating H2 (Fu et al, 2003; Tibiletti et al, 2005; Reina et al, 2014)
We recently showed using stop-start HAADF STEM and Xray photoelectron spectroscopy (XPS) that in addition to morphological changes, particle agglomeration occurs under comparable LTS reaction conditions at 150◦C (Carter et al, 2017)
It was previously established that the optimum Ce:Zr molar ratio for gold-catalyzed LTS was 1:1 (Pilasombat et al, 2012), Ce0.5Zr0.5O2 was used as the benchmark catalyst support

Summary

Introduction

The low-temperature water-gas shift (LTS) reaction has been extensively studied in recent years as a means of upgrading reformate by removing CO and generating H2 (Fu et al, 2003; Tibiletti et al, 2005; Reina et al, 2014). Au/CeO2 was initially reported to be highly active for the LTS reaction (Fu et al, 2001) and more recently Hardacre et al demonstrated that the addition of Zr to the CeO2 support resulted in a remarkable enhancement of catalyst activity (Tibiletti et al, 2005).

Results

Conclusion