Reproducible preparation of Au/TS-1 with high reaction rate for gas phase epoxidation of propylene
Date of this Version3-2012
Journal of Catalysis Volume 287, March 2012, Pages 178–189
A refined and reliable synthesis procedure for Au/TS-1(Si/Ti molar ratio 100) with high reaction rate for the direct gas phase epoxidation of propylene has been developed by studying the effects of pH of the gold slurry solution, mixing time, and preparation temperature for deposition precipitation (DP) of Au on TS-1 supports. Au/TS-1 catalysts prepared at optimal DP conditions (pH similar to 7.3, mixing for 9.5 h, room temperature) showed an average PO rate similar to 160 g(PO) h(-1) kg(Cat)(-1) at 200 degrees C at 1 atm. A reproducibility better than +/- 10% was demonstrated by nine independent samples prepared at the same conditions. These are the highest rates yet reported at 200 degrees C. No visible gold particles were observed by the HRTEM analysis in the fresh Au/TS-1 with gold loading up to similar to 0.1 wt%, indicating that the gold species were smaller than 1 nm. Additionally, the rate per gram of Au and the catalyst stability increased as the Au loading decreased, giving a maximum value of 500 g(PO) h(-1) g(Au)(-1), and Si/Ti molar ratios of similar to 100 gave the highest rates. (C) 2011 Elsevier Inc. All rights reserved.
Nanoscience and Nanotechnology