Research output: Contribution to journal › Article › peer-review
Does the Zn2+ Species Introduced into H-ZSM-5 Zeolite Affect the Strength of Brønsted Acid Sites? / Gabrienko, Anton A.; Danilova, Irina G.; Arzumanov, Sergei S. et al.
In: ChemCatChem, Vol. 12, No. 2, 18.01.2020, p. 478-487.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Does the Zn2+ Species Introduced into H-ZSM-5 Zeolite Affect the Strength of Brønsted Acid Sites?
AU - Gabrienko, Anton A.
AU - Danilova, Irina G.
AU - Arzumanov, Sergei S.
AU - Freude, Dieter
AU - Stepanov, Alexander G.
PY - 2020/1/18
Y1 - 2020/1/18
N2 - To clarify the issue on Brønsted acidity enhancement by the presence of zinc species in H-ZSM-5 zeolite (G.D. Qi, et al., Angew. Chem.-Int. Edit. 2016, 55, 15826), the influence of Zn2+ cationic species, introduced into the zeolite, on the strength of Brønsted acid sites (BAS) has been analyzed by solid-state NMR and FTIR techniques using trimethylphosphine (TMP) and CO as probe molecules. Comparative analysis of the acidity for H-ZSM-5 and Zn2+/H-ZSM-5 zeolites has been performed. TMP adsorbed on both zeolite samples exhibits same signals at 6.3 and −4.5 ppm in 1H and 31P MAS NMR spectra, respectively, assigned to protonated TMP. FTIR spectroscopy has shown that both zeolite samples, H-ZSM-5 and Zn2+/H-ZSM-5, display the same red frequency shift (ΔνOH⋅⋅⋅CO=−318 cm−1) of the O−H stretching band and the same blue frequency shift (ΔνCO=+32 cm−1) of the CO stretching band for CO adsorption complex with BAS. The results obtained do not provide any evidence for the existence of some specific BAS with enhanced acid strength for Zn2+-exchanged zeolite compared to the strength inherent to pure acid-form zeolite. It is thus inferred the strength of BAS in H-ZSM-5 zeolite is not affected by the modification of the zeolite with Zn2+ cationic species.
AB - To clarify the issue on Brønsted acidity enhancement by the presence of zinc species in H-ZSM-5 zeolite (G.D. Qi, et al., Angew. Chem.-Int. Edit. 2016, 55, 15826), the influence of Zn2+ cationic species, introduced into the zeolite, on the strength of Brønsted acid sites (BAS) has been analyzed by solid-state NMR and FTIR techniques using trimethylphosphine (TMP) and CO as probe molecules. Comparative analysis of the acidity for H-ZSM-5 and Zn2+/H-ZSM-5 zeolites has been performed. TMP adsorbed on both zeolite samples exhibits same signals at 6.3 and −4.5 ppm in 1H and 31P MAS NMR spectra, respectively, assigned to protonated TMP. FTIR spectroscopy has shown that both zeolite samples, H-ZSM-5 and Zn2+/H-ZSM-5, display the same red frequency shift (ΔνOH⋅⋅⋅CO=−318 cm−1) of the O−H stretching band and the same blue frequency shift (ΔνCO=+32 cm−1) of the CO stretching band for CO adsorption complex with BAS. The results obtained do not provide any evidence for the existence of some specific BAS with enhanced acid strength for Zn2+-exchanged zeolite compared to the strength inherent to pure acid-form zeolite. It is thus inferred the strength of BAS in H-ZSM-5 zeolite is not affected by the modification of the zeolite with Zn2+ cationic species.
KW - Brønsted acid sites
KW - FTIR spectroscopy
KW - solid-state NMR
KW - zeolite
KW - zinc
KW - HYDROXYL-GROUPS
KW - surface
KW - heterogeneous catalysis
KW - nanoreactor
KW - Superaerophilic
KW - DISSOCIATIVE ADSORPTION
KW - METHANE ACTIVATION
KW - PROTON AFFINITY
KW - CARBON-MONOXIDE
KW - LIGHT PARAFFINS
KW - BRONSTED ACID SITES
KW - TRIMETHYLPHOSPHINE OXIDE
KW - STRETCHING BANDS
KW - bursting
KW - STATE NMR
UR - http://www.scopus.com/inward/record.url?scp=85074781925&partnerID=8YFLogxK
U2 - 10.1002/cctc.201901637
DO - 10.1002/cctc.201901637
M3 - Article
AN - SCOPUS:85074781925
VL - 12
SP - 478
EP - 487
JO - ChemCatChem
JF - ChemCatChem
SN - 1867-3880
IS - 2
ER -
ID: 22319652