resolver

H 2
adsorbed, mmol/g
94 Chapter 4
Furthermore, CO adsorption of the parent Ru-MOF, 1a and 1c at 298 K also illustrates the
tendency of enhanced uptake in case of the Ru-DEMOF samples (Figure 4.28). The small
difference between the sample 1a and the parent Ru-MOF on CO adsorption is attributed
to the low incorporation degree of the 5-OH-ip DL (8%). Along with the increase of the DL
incorporation (such as in 1c), the CO uptake rises even at very low pressure (ca. 4 mbar).
This increase of the CO capacity of the Ru-DEMOF is probably due to the generation of the
modified paddlewheels of type A, which expose more open sites as one carboxylate
ligator-site of BTC is substituted by the hydroxyl-group of 5-OH-ip. Besides, the average
electronic density is varied as the oxidation state of ruthenium at the CUS is changed. Both
could contribute to the enhancement of the adsorption properties.
10
8
6
4
2
parent Ru-MOF
1a
1c
0
200 400 600 800 1000
P, mbar
Figure 4.29. H 2 isotherms measured at 77 K for the parent Ru-MOF and DEMOFs 1a (8%) and 1c
(32%) with 5-OH-ip DL. Black circles – parent Ru-MOF; blue triangles – 1a; magenta squares – 1c.
The H2 adsorption isotherms (at 77 K) of the parent Ru-MOF and the Ru-DEMOFs 1a and
1c follow nearly the same trend as in case of CO2 and CO adsorption (Figure 4.29). Both
defect-engineered materials 1a and 1c exhibit higher H2 uptake at 1 bar than the parent
intact framework. In fact, there should be two main kinds of adsorption sites in the Ru-