Acta Phys. -Chim. Sin. ›› 1998, Vol. 14 ›› Issue (11): 1013-1019.doi: 10.3866/PKU.WHXB19981110

• ARTICLE • Previous Articles     Next Articles

Structure and Hydroformylation Performance of Supported Aqueous-phase Rh Catalyst

Yuan You-Zhu, Zhang Yu, Chen Zhong, Zhang Hong-Bin, Cai Qi-Rui   

  1. Department of Chemistry,Institute of Physical Chemistry,State Key Laboratory for Physical Chemistry of Solid Surface,Xiamen University,Xiamen 361005
  • Received:1998-02-09 Revised:1998-06-04 Published:1998-11-15
  • Contact: Yuan You-Zhu

Abstract:

The catalytic activity of hydroformylation of 1-hexene over SiO2-supported TPPTSRh(acac)(CO)2 (SAPC) was found to be evidently promoted when a proper amount of water-vapor was introduced into the reactant. Characterization results by using MAS NMR 31p spectra revealed that there were three types of phosphine species in the as-prepared SAPC: uncoordinated ligand TPPTS (over 70 mol%), surface complex {Rh(CO)(TPPTS)2} (chemical shift at δ=32.4, about 15 mol%), and unknown (about 10 mol%). By pre-treatment at 373 K for 2 under dry-snygas or at 333 K for 2 h under wet-syngas, the amount of phosphine species of the surface complex{Rh(CO)(TPPTS)2} was slightly increased to 20-30mol%, accompanying a few changes in ratios of the other phsophine species. When the SAPC was pre-treated at 373 K for 2 h under wet-syngas, however, the phosphine species at chemical shift of 32.4 was increased by over 40 mol% due to the in-situ formation of the surface complex {Rh(CO)(TPPTS)2}. It was found that the peak at δ=32.4 was also a principal one in the MAS NMR 31P spectra of the working SAPC, which demonstrated that the surface complex of {Rh(CO)(TPPTS)2 } would be a catalytic active species for olefin hydroformyaltion. After hydroformylation for 43 h, the deactivation of the catalyst occurred, corresponding to the observations of a broadness in peak ascribed to the surface complex of {An(CO)(TPPTS)z} in the MAS NMR 31P spectra, indicating that there existed de-coordination of the surface complex and oxidation of the ligand TPPTS during the reaction. The results suggest that a proper amount of water-vapor was able to accelerate the formation of active Rh-complex on the catalyst surface and thus increase the catalytic activity, whereas, it could be inevitably to cause the de-coordination of the surface complex and the oxidation of phosphine ligand under the reaction condition, hence leading to the deactivation of the catalyst.

Key words: Hydroformylation, Supported aqueous-phase catalyst, MAS NMR31P spectroscopy, 1-hexene