Factors affecting the synthesis of cobalt-titanium silicalite-1 catalyst

Abstract

This research has studied factors affecting the preparation of Co-TS-1 catalysts which were synthesized by the hydrothermal method. The atomic rations of Si/Ti and Si/Co were set at as 50 and 150, respectively. The synthesized TS-1 that incorporated with various types of cobalt salt ((Co(No₃)₂)-6H₂O, CoCl ₂-6H ₂O and Co(C₂H₃O₂)₂-4H₂O) and different loading solutions (A1, A2, C1 and A1A2 solutions). The Co-TS-1 catalysts were characterized by various techniques XRF, SEM, XRD, BET, FT-IR and NH₃-TPD. The catalytic activity of Co-TS-1 were investigated by using the gas phase oxidation reaction of 2-propanol as the test reaction. The gas mixtures for oxidation reaction were 5 vol%-2propanol and 8 vol% oxygen at temperature between 100-500 degrees celsius. The study reveals that the various types of cobalt salt and different loading solution of incorporated cobalt have effect to the amount of cobalt and titanium that can incorporate into framework. Because of the different pH value of each salt, the high pH value of cobalt salt as a base is suitable for cobalt loading. However, the formed catalysts can still maintain MFI structure and orthorhombic crystal shape. The majority of cobalt metal only offered to the gel solution can incorporate into TS-1 framework. The NH₃-TPD shows that the existence of cobalt in framework increases the amount of stronger acid sites ratio rather than the non-existence cobalt catalyst. Moreover, the higher amount of cobalt that incorporated into TS-1 framework will increase the weaker acid sites ratio. Therefore, the increasing of cobalt metal also results in the increasing of total acid sites. Because of those properties, when the catalyst sample with higher amount of loaded cobalt is tested by 2-propanol oxidation, the higher catalytic activity for the dehydration reaction toward propylene is increased.