Effects of water and ion-exchanged counterion on the FTIR spectra of ZSM-5. I. NaH-ZSM-5:

摘要: Abstract A dried (773 K, Ar, 1 h) NaH-ZSM-5 sample (Si/Al = 20, Na/Al = 0.5) showed two sharp O–H vibrations at 3745 cm −1 (SiOH, terminal OH) and 3612 cm [Si(OH)Al, bridged OH], a weak, wide band 3300–3200 cm due to H-bonded OH three characteristic (T–O–T) 1268, 975 834 cm external asymmetric ( ν as ext ), internal int ) symmetric sym stretching lattice vibrations, respectively. The value of 975 cm obtained here for the charge-sensitive ZSM-5, was in good accordance with earlier results gained bare Cu + , –CO or 2+ containing ZSM-5. broadening 1010–990 cm indicated an incomplete ion-exchange H by Na during preparation from H-ZSM-5. Depending on amount, water markedly influenced almost whole FTIR spectra NaH-ZSM-5, increasing more less intensities bands. At high 2 O concentration, ligands aquacomplex completely screened positive charge ions. As result, perturbation effect disappeared, since blueshifted 1010 cm . Strongly interactions Fermi resonance formation (H O) n highly suggested medium concentration O, Even higher temperatures, part silanol groups revealed unusually strong molecules retained probably cations. 880 cm attributed out-of-plane bending mode bands varied relation each other, different stages.