Supported Rhodium Phosphine Complex Catalysts For Isobutene Hydroformylation

Catalysts for olefin hydroformylation include Co-base catalysts and Rh-base catalysts mainly. Though very costly, Rh-base catalysts are much higher of activity, and much milder of reaction condition than Co-base catalysts, leading to being concerned extremely. Rh-base catalysts applied industrially include two kinds of catalysts, one is the homogeneous catalysts, which are represented by HRh(CO)(PPh₃)₃, the other is the water/organic bi-phase catalysts, which are represented by HRh(CO)(TPPTS)₃. They are both suitable for hydroformylation of low-carbon olefin only. As hydroformylation of high-carbon olefin is concerned, the former have the problem of separating the homogeneous catalysts from product, and the latter have low activity for the low solubility of high-carbon olefin. Immobilized homogeneous catalysts have been attracting widespread interesting, since such catalysts can combine the high activity and selectivity of homogeneous catalysts and ease of separation of heterogeneous catalysts. But it isn't still applied to industry for Rhodium supported on catalysts would be washed away grievously during process of olefin hydroformylation. It is important of meanings for exploiting supported catalysts which not only have high activity and selectivity, but also high stability.Isovaleraldehyde is a spice aldehyde that can be eaten according to the national regulation, and also one of the important intermediate. Isobutene hydroformylation is one of important way to synthesize isovaleraldehyde, and hasthe advantage of low cost and high yield. The purpose of this thesis was in search of a supported catalyst which not only had high activity and selectivity, but high stability through heterogenization of homogeneous Rhodium phosphine complex tethered by heteropolyacid.At first, it was investigated the effect of support, which functioned through phosphotungstic acid, on catalytic properties. The results indicated that the activity of supported catalysts didn't decrease when compared with homogeneous ones. When functioned SiC>2 acted as support, the activity of catalyst was very high. Circumfluence impregnation was favor of enhancing stability of catalyst, and catalytic properties of catalyst was better when drying at 120 °C than at 220 °C.Then, it was investigated the effect on catalytic properties of Rhodium phosphine complex and tethering agent. The results indicated that the activity and stability of the catalyst, which was heterogenized of HRh(CO)(PPh3)3 tethered to SiC>2 functioned through phosphotungstic acid, was the best than others. The catalysts, the support of which functioned through H3PM012O40, had very low stability, and had no activity any more when used in second cycle. When 1-hexane acted as impregnation solution, the catalysts had low stability although it had better activity than catalysts when ethanol acted as impregnation solution. So it was more suitable for that ethanol acted as impregnation solution than 1-hexane.At last, it was investigated the effect on catalytic reaction of P/Rh ratio in reaction solution, catalyst mass, isobutene mass, reaction temperature, and reaction time. The optimum results of reaction condition were that catalyst mass was 7.05 mmol/L, isobutene mass was 0.89 mol/L, reaction temperature was 100 °C, reaction time was 5 h.