The influence of Fe on the formation of titanosilicate ETS-4

Abstract

ETS-4 has potential applications for the size-selective adsorption and ion exchange. Iron substituted ETS-4 has been hydrothermally synthesized. The incorporation with different amount of iron has been achieved to produce Fe-ETS-4(x) (x=5–13), which shows the flexibility for iron substitution. Low amount of iron in precursor does not disturb the formation of ETS-4. The existence of iron was confirmed by EDS. Direct comparison between in-situ synthesized and iron exchanged samples suggested that iron in former ones does not exist in pore. The iron in the pore of ETS-4 would significantly shift the 29Si MAS NMR resonance upfield. While in-situ synthesized Fe-ETS-4(x) samples present very similar FTIR and Raman spectra, TG and DSC curves to ETS-4, the iron exchanged ones are clear shifted. The thermal stability of in-situ synthesized Fe-ETS-4(x) samples is very similar to the parent phase, much better than that of iron exchanged one.