[Rh(μ-Cl)(COD)]2 supported on activated carbons for the hydroformylation of 1-octene: effects of support surface chemistry and solvent

The Rh(μ-Cl)(COD)]₂ complex has been heterogeneised on activated carbon and used as catalysts for the hydroformylation of 1-octene. The objective is to achieve the effective anchorage of the complex on the carbon surface, keeping or improving the catalytic properties of the complex in the homogeneous process. The effects of surface chemistry of the activated carbon and the solvent used as reaction media (hexane, acetone or methanol) on the activity and selectivity to linear products (alcohols and aldehydes) and on the lixiviation of the complex from support, using different methods of catalyst recovering, are investigated. Gas adsorption, temperature-programmed desorption (TPD), immersion calorimetry and XPS techniques were used for characterisation. Catalytic activity at 353 K and a total pressure of 5 MPa (H₂:CO ratio 1:1) was carried out in a stainless steel stirred tank reactor. Obtained results show that the heterogeneised complex shows a conversion level higher or similar to that of the homogeneous complex and with a higher selectivity to the linear products. Complex lixiviation depends on the support, the solvent and the method used to recover the catalyst from the reactor. The catalyst prepared with the functionalised activated carbon, where the anchorage takes place by ion-exchange, is more stable and active in further catalytic runs using the proper recovering method.