(347d) Deep Hydrogenation of Tetralin over Pt/Pd Catalysts: Influence of Fluorine and Catalyst Preparation

The removal of poly-aromatics from diesel fuel has stimulated intense research because of increased stringent environmental legislation. Deep hydrogenation can greatly enhance the quality of diesel fuel. Platinum and palladium catalysts are well known as noble metals widely used in the hydrogenation reaction at low temperatures. The addition of F was found to increase sulfur tolerance for the catalysts. The condition in catalyst preparation, such as calcination temperature and the order of impregnation between metal and F-promoter has an effect on the activity and properties of the catalyst. The purpose of this work was to investigate the influence of catalyst preparation on deep hydrogenation of tetralin over Pt/Pd catalysts. A series of mono- and bi-metallic catalysts (with and without F-promoter) were prepared by incipient wetness impregnation and calcined at different temperatures (250, 300 and 350°C). The hydrogenation reaction was carried out at 275°C with a total pressure of 300 psig. The results showed that the activity of tetralin hydrogenation decreased in the order of Pt > Pd > PtPd. The addition of F increased the activity for Pd/Al2O3 and PtPd/Al2O3 but decreased the activity for Pt/Al2O3. For the order of impregnation, the catalyst prepared by adding metal before F gave a better catalytic activity than the ones prepared by adding F before metal. The suitable calcination temperature for unpromoted catalysts, F-promoted Pd, and F-promoted PtPd catalysts was 350°C while the suitable calcination temperature for F-promoted Pt catalyst was 300°C. TPR showed strong interaction between metal and support when F was added to Pd catalysts. For Pt catalysts, TPR results indicated that the metal was already reduced during the calcination of F precursor. The sulfur tolerance of the catalyst will be further investigated.