Rh-TPPTS intercalated layered double hydroxides as hydroformylation catalyst

Trans-RhCl(CO)(TPPTS)(2) [TPPTS, trisodium salt of tri-(m-sulfophenyl)-phosphine] and TPPTS ligands have been cointercalated into zinc-aluminum-layered double hydroxides (ZnAl-LDHs) by in situ complexation, and the catalytic performances of the resulting materials for 1-hexene hydroformylation have been investigated. The intercalated materials were characterized by means of XRD, FTIR, ICP, and (31)p MAS NMR. The rhodium complex and TPPTS ligands coexist in the interlayer galleries of LDH (denoted as RhP2-P-ZnnAl-LDH, where n denotes as the molar ratio Zn/Al), with an interlayer spacing of ca. 1.58 nm. Compared with the catalytic properties of the corresponding water-oil biphasic catalyst under similar reaction conditions, RhP2-P-Zn3Al-LDH showed better reusability and activity. Furthermore, compared with a related material prepared by ion exchange, the RhP2-P-Zn3Al-LDH showed better activity and selectivity towards aldehyde. The influence of the Zn/Al molar ratio in RhP2-P-ZnnAl-LDH has also been studied, and it was found that higher selectivity to aldehydes and lower activity were obtained with increasing Zn/Al molar ratio. (C) 2007 American Institute of Chemical Engineers.