TY - JOUR
T1 - Sulfation of metal-organic frameworks
T2 - Opportunities for acid catalysis and proton conductivity
AU - Goesten, Maarten G.
AU - Juan-Alcañiz, Jana
AU - Ramos-Fernandez, Enrique V.
AU - Sai Sankar Gupta, K. B.
AU - Stavitski, Eli
AU - Van Bekkum, Herman
AU - Gascon Sabate, Jorge
AU - Kapteijn, Freek
PY - 2011/7/1
Y1 - 2011/7/1
N2 - A new post-functionalization method for metal-organic frameworks (MOFs) has been developed to introduce acidity for catalysis. Upon treatment with a mixture of triflic anhydride and sulfuric acid, chemically stable MOF structures MIL-101(Cr) and MIL-53(Al) can be sulfated, resulting in a Brønsted sulfoxy acid group attached to up to 50% of the aromatic terephthalate linkers of the structure. The sulfated samples have been extensively characterized by solid-state NMR, XANES, and FTIR spectroscopy. The functionalized acidic frameworks show catalytic activity similar to that of acidic polymers like Nafion® display in the esterification of n-butanol with acetic acid (TOF ∼ 1 min
-1 @ 343 K). Water adsorbs strongly up to 4 molecules per sulfoxy acid group, and an additional 2 molecules are taken up at lower temperatures in the 1-D pore channels of S-MIL-53(Al). The high water content and Brønsted acidity provide the structure S-MIL-53(Al) a high proton conductivity up to moderate temperatures.
AB - A new post-functionalization method for metal-organic frameworks (MOFs) has been developed to introduce acidity for catalysis. Upon treatment with a mixture of triflic anhydride and sulfuric acid, chemically stable MOF structures MIL-101(Cr) and MIL-53(Al) can be sulfated, resulting in a Brønsted sulfoxy acid group attached to up to 50% of the aromatic terephthalate linkers of the structure. The sulfated samples have been extensively characterized by solid-state NMR, XANES, and FTIR spectroscopy. The functionalized acidic frameworks show catalytic activity similar to that of acidic polymers like Nafion® display in the esterification of n-butanol with acetic acid (TOF ∼ 1 min
-1 @ 343 K). Water adsorbs strongly up to 4 molecules per sulfoxy acid group, and an additional 2 molecules are taken up at lower temperatures in the 1-D pore channels of S-MIL-53(Al). The high water content and Brønsted acidity provide the structure S-MIL-53(Al) a high proton conductivity up to moderate temperatures.
KW - Esterification
KW - Flexibility
KW - MIL-101
KW - MIL-53
KW - Metal-organic frameworks
KW - Proton conductivity
UR - http://www.scopus.com/inward/record.url?scp=79958100804&partnerID=8YFLogxK
U2 - 10.1016/j.jcat.2011.04.015
DO - 10.1016/j.jcat.2011.04.015
M3 - Article
AN - SCOPUS:79958100804
SN - 0021-9517
VL - 281
SP - 177
EP - 187
JO - Journal of Catalysis
JF - Journal of Catalysis
IS - 1
ER -