In Situ Single-crystal X‑ray
Diffraction Studies of Physisorption and Chemisorption of SO2 within a Metal–Organic Framework and Its Competitive Adsorption
with Water
posted on 2024-01-26, 13:04authored byRussell M. Main, Simon M. Vornholt, Romy Ettlinger, Philip Netzsch, Maximillian G. Stanzione, Cameron M. Rice, Caroline Elliott, Samantha E. Russell, Mark R. Warren, Sharon E. Ashbrook, Russell E. Morris
Living on an increasingly polluted planet, the removal
of toxic
pollutants such as sulfur dioxide (SO2) from the troposphere
and power station flue gas is becoming more and more important. The
CPO-27/MOF-74 family of metal–organic frameworks (MOFs) with
their high densities of open metal sites is well suited for the selective
adsorption of gases that, like SO2, bind well to metals
and have been extensively researched both practically and through
computer simulations. However, until now, focus has centered upon
the binding of SO2 to the open metal sites in this MOF
(called chemisorption, where the adsorbent–adsorbate interaction
is through a chemical bond). The possibility of physisorption (where
the adsorbent–adsorbate interaction is only through weak intermolecular
forces) has not been identified experimentally. This work presents
an in situ single-crystal X-ray diffraction (scXRD)
study that identifies discrete adsorption sites within Ni-MOF-74/Ni-CPO-27,
where SO2 is both chemisorbed and physisorbed while also
probing competitive adsorption of SO2 of these sites when
water is present. Further features of this site have been confirmed
by variable SO2 pressure scXRD studies, DFT calculations,
and IR studies.