Catalysis Today, Vol.244, 19-28, 2015
Revisiting the synthesis of Au/TiO2 P25 catalyst and application in the low temperature water-gas shift under realistic conditions
The performance of Au/TiO2 P25 synthesized at different pH's (8, 9 and 10) is studied over time-on-stream in low temperature water-gas shift (WGS) at 21 bar under semi-industrial conditions. Furthermore, their performance is compared with a commercial CuO/ZnO/Al2O3 low temperature WGS catalyst and AUROlite 1 wt.% Au/TiO2 as a reference. Sulfur severely poisons the Au/TiO2 catalyst, which is irreversible over time-on-stream under high pressure (21 bar) WGS conditions. The Au/TiO2 P25 catalysts are synthesized using deposition precipitation to a targeted loading of gold close to 1 wt.% and are carried at three different pH (8, 9 and 10) under controlled conditions. The influence of parameters such as final pH, rate of addition of basic solution, type of basic solution are discussed. A higher final pH resulted in smaller gold particles deposited on TiO2-P25. The Au/TiO2-P25 catalyst prepared at the higher final pH (pH 10) showed higher WGS activity which relates to the averaged smaller particle size of the gold on TiO2-P25. The Au/TiO2-P25 catalyst prepared at lower final pH (pH of 8) is stable, while the catalysts prepared at pH of 9 and 10 deactivate over 130 h timeon stream. (C) 2014 Elsevier B.V. All rights reserved.