TY - JOUR
T1 - Influence of Levulinic Acid Hydrogenation on Aluminum Coordination in Zeolite-Supported Ruthenium Catalysts
T2 - A27Al 3QMAS Nuclear Magnetic Resonance Study
AU - Luo, Wenhao
AU - vanEck, Ernst R.H.
AU - Bruijnincx, Pieter C.A.
AU - Weckhuysen, Bert M.
PY - 2018/2/19
Y1 - 2018/2/19
N2 - The influence of a highly oxygenated, polar protic reaction medium, that is, levulinic acid in 2-ethylhexanoic acid, on the dealumination of two zeolite-supported ruthenium catalysts, namely Ru/H-β and Ru/H-ZSM-5, has been investigated by 27Al triple-quantum magic-angle spinning nuclear magnetic resonance spectroscopy (3QMAS NMR). Upon use of these catalysts in the hydrogenation of levulinic acid, the heterogeneity in aluminum speciation is found to increase for both Ru/H-ZSM-5 and Ru/H-β. For Ru/H-ZSM-5, the symmetric, tetrahedral framework aluminum species (FAL) were found to be mainly converted into distorted tetrahedral FAL species, with limited loss of aluminum to the solution by leaching. A severe loss of both FAL and extra-framework aluminum (EFAL) species into the liquid phase was observed for Ru/H-β instead. The large decrease in tetrahedral FAL species, in particular, results in a significant decrease in strong acid sites, as corroborated by Fourier transform infrared spectroscopy (FT-IR). This decrease in acidity, evidence of the inferior stability of the strongly acidic sites in Ru/H-β relative to Ru/H-ZSM-5 under the applied conditions, is considered as the main reason for differences seen in catalyst performance.
AB - The influence of a highly oxygenated, polar protic reaction medium, that is, levulinic acid in 2-ethylhexanoic acid, on the dealumination of two zeolite-supported ruthenium catalysts, namely Ru/H-β and Ru/H-ZSM-5, has been investigated by 27Al triple-quantum magic-angle spinning nuclear magnetic resonance spectroscopy (3QMAS NMR). Upon use of these catalysts in the hydrogenation of levulinic acid, the heterogeneity in aluminum speciation is found to increase for both Ru/H-ZSM-5 and Ru/H-β. For Ru/H-ZSM-5, the symmetric, tetrahedral framework aluminum species (FAL) were found to be mainly converted into distorted tetrahedral FAL species, with limited loss of aluminum to the solution by leaching. A severe loss of both FAL and extra-framework aluminum (EFAL) species into the liquid phase was observed for Ru/H-β instead. The large decrease in tetrahedral FAL species, in particular, results in a significant decrease in strong acid sites, as corroborated by Fourier transform infrared spectroscopy (FT-IR). This decrease in acidity, evidence of the inferior stability of the strongly acidic sites in Ru/H-β relative to Ru/H-ZSM-5 under the applied conditions, is considered as the main reason for differences seen in catalyst performance.
KW - Aluminum
KW - Hydrogenation
KW - Levulinic acid
KW - Nuclear magnetic resonance
KW - Zeolites
UR - http://www.scopus.com/inward/record.url?scp=85034747291&partnerID=8YFLogxK
U2 - 10.1002/cphc.201700785
DO - 10.1002/cphc.201700785
M3 - Article
AN - SCOPUS:85034747291
SN - 1439-4235
VL - 19
SP - 379
EP - 385
JO - ChemPhysChem
JF - ChemPhysChem
IS - 4
ER -