Preparation, Structure And Catalytic Performance Of Rhodium-Phosphine Complexes Intercalated Layered Double Hydroxides

Based on the concept of intercalation chemistry of layered double hydroxides (LDHs), RhCl(CO)(TPPTS)₂ (TPPTS: P(m-C₆H₄SO₃Na)₃) intercalated LDHs as well as RhCl(CO)(TPPTS)₂ and TPPTS co-intercalated LDHs have been successfully synthesized by using ions exchange and in-situ complexation methods, respectively. Characterizations by the use of XRD, FT-IR, ICP, ³¹P NMR, TG/DTA and in-situ HT-XRD techniques confirm the supramolecular structure of the two kinds of catalytic species intercalated LDHs. The catalytic mechanism for the interlayer hydroformylation of 1-hexene as well as the relationship between the structural parameters and the catalytic performance of intercalated catalyst have been systematically investigated.According to the catalytic performance, it can be concluded that the stability and reusability of intercalated catalyst are much better than those of corresponding water-oil biphasic catalyst. This can be attributed to the little leaching of the active species from the carrier because of the strong electrostatic interaction between the LDHs layers and interlayer catalytic species. The catalytic performance of the intercalated catalyst also shows that the basic nature of LDHs plays a significant role in the improvement of catalytic activity, which could be explained by the catalytic mechanism for the interlayer hydroformylation of 1-hexene. Moreover, the special structure of LDHs carrier has great influence on the selectivity of intercalated catalyst due to the steric effect.The relationship between the structural parameters and the catalytic performance has been studied in detail. As a consequence of the changes in structure parameter, such as the basic nature of layers, the interaction between the layers and interlayer species as well as the loaded weight and P/Rh molar ratio of catalytic species, the intercalated catalyst presents marked difference in catalytic performance. All the observations above could be interpreted by the catalytic mechanism and LDHs structural features.Therefore, the Rh-phosphine complex-inorganic layered material in this work provides a potential candidate for exploitation of supported catalyst for hydroformylation.