Au/TS-1 catalyst prepared by deposition-precipitation method for propene epoxidation with H-2/O-2: Insights into the effects of slurry aging time and Si/Ti molar ratio

摘要

Au/TS-1 catalyst prepared by deposition-precipitation method is efficient for propene epoxidation with H-2/O-2, and its performance is significantly affected by the preparation parameters and the properties of support. In this work, effects of the slurry aging time and Si/Ti ratio of support on the location of Au nanoparticles inside or outside the micropores of TS-1 supports are examined by multi-techniques such as in situ characterization and molecular dynamics simulation, and the as-obtained catalysts are tested for propene epoxidation. It is found that longer slurry aging time facilitates the evolution of Au complex into smaller sized species which is easier to locate inside the micropores. Accordingly, the as-reduced catalyst has more tiny Au nanoparticles that are extremely active inside micropores and shows higher initial PO formation rate (gpo h(-1) g(Au)(-1)). In addition, high Si/Ti ratio of TS-1 also favors the deposition of Au nanoparticles inside micropores, resulting in higher initial activity but lower stable activity. (C) 2015 Elsevier Inc. All rights reserved.