Propene epoxidation titania-supported catalyst

A flow reactor was used to determine the catalytic performance of the different catalysts. The experiments were carried out with typically 0.30 g of catalyst and a gas flow of 50 Nml/min (GHSV 10,000 h ). In the epoxidation experiments, a gas mixture was used similar to that in most research in the literature 10% of oxygen, 10% of hydrogen, and 10% of propene in helium (all gas compositions given in vol.%). The pressure was 1.1 bar. In this study, the activity was determined at 323, 373,423, and 473 K the lowest temperature being most appropriate for the titania-supported catalyst, the higher temperatures being more optimal for the Ti-silica-supported catalysts. 

A. Lange de Oliveira, A. Wolf, E. Schueth, Highly selective propene epoxidation with hydrogen/ oxygen mixtures over titania-supported silver catalysts, Catal. Lett. 73 (2001) 157. 

Both catalysts supported on silica produce a small amoimt of propene oxide at the highest temperatures however, the selectivities remain low, proving the necessity of titania on the support to have an effective epoxidation catalyst. Furthermore, these catalysts by far have the lowest hydrogen efficiency because of the direct oxidation of hydrogen into water, making the economics of these catalysts very unattractive. 

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