Studies On Catalysts For Isobutene Hydroformylation To Isovaleraldehyde

Olefin hydroformylation is an important way to produce aldehyde, and isobutene hydroformylation to form isovaleraldehyde is very interesting because the product is widely used in many fields. As the key technology to hydroformylation, the catalysts are mainly divided into Co-based one and Rh-based one. The former is not active enough and the reaction conditions are very harsh; the latter can be used in mild conditions with high activity and selectivity, so it`s much attractive to numerous researchers. Among Rh-based catalysts, the homogenous one is difficult to be recovered from hydroformyaltion products, while the biphased one is limited in lower olifen hydroformylation due to the low solubility of higher olefin in water, and the supported liquid-phased catalyst is troubled by the leaching of active metal. So it is necessary to develop new catalysts with good performance. In this thesis, isobutene hydroformylation to isovaleraldehyde was explored over homogenous rhodium phosphine complex catalyst prepared in situ. The product isovaleraldehyde was seperated with the catalyst and its purity was not lower than 95%. Biphased catalyst was also studied in this reaction and the best performance was gotten in the condition the ratio of oil/water was 20/80 and the pH value was about 7. This thesis studied the supported Rh-Co bimetalic catalysts. The silica supported Rh-Co bimetallic catalysts were prepared by impregnation method, characterized by TPR, TPD and FT-IR, and examined by isobutene hydroformylation as the probe reaction. The results showed that the dispersion of Rh and Co on support were enhanced as a result of the synergistic effect between each other. The formation of catalytic species was promoted by Co and Rh synergy, which may be the reason for the catalytic performance enhancement. What`s more, the reaction conditions were optimized. Plasma receives much concern of catalysis researchers due to its novel property. It was introduced into the field of hydroformylation for first time in this thesis. The method of treatment by plasma was studied, it showed that plasma could increase the dispersion of active metal on the support, and hence to enhance the catalytic behavior.