1. Sorption 101: Types of sorption
Chemical vs. physical
Physisorption
Weak forces (van der Waals, polarization) = easily Recyclable
Low selectivity
Typically fast
Chemisorption
Strong forces (chemical bonds) =
hard to recycle
High selectivity
Typically slow 1

2. Sorption 201:Types of physisorbent
Classification by pore size
Mesoporous
2 – 50 nm
Microporous
< 2.0 nm
Ultramicroporous
< 0.7 nm 2

3. THE RIGHT PORE SIZE MEANS EVERYTHING
Sorption 301: Ultramicroporous materials
Size really, really matters
THE RIGHT PORE SIZE MEANS EVERYTHING
Abe Stern and Brian Space, 2008, unpublished results 3

4. My favourite space group
Brian Space
Tony Pham 4

5. What about pore chemistry?
Pore chemistry affects sorption properties in rht MOFs 1
PCN-61
Ligand size
1.36
1.41
Space gp
Fm3barm
Cell volume
74901 (3)
78379 (7)
CubOh size
1.2
T-Td size
1.16
1.18
T-Oh size
1.87
1.88
SLang/SBET
3570/3160
3500/3000
VPore
1.27
CO2 uptake
bar
bar
(23.5) 35bar
Qst (CO2)
26.2
22.0
CO2 isotherms
N2 isotherms
CO2 Qst
B. Zheng, J. Bai, J. Duan, L. Wojtas, M.J. Zaworotko, J. Am. Chem. Soc , 5

6. Properly activated and sorption studied in early 2012
SIFSIX-3-Zn: [Zn(pyrazine)2(SiF6)]n
Structure reported in 2009 by Uemura et al.
Properly activated and sorption studied in early 2012
3.8 Å = ultramicropores
SIFSIX
Hybrid
Ultramicroporous
Material (HUM)
HUMs ≠ MOFs
Stephen Burd Amanda Diaz Amy Engel 6

7. HUMs offer design principles
Narrow pores + inorganic walls
Binding sites with strong interactions = high selectivity
High density of binding sites = good working capacity
Single binding site = high Qst across loading
CO2/N2
Selectivty > 2500
Nature, 2013
C2H2/C2H4
Selectivity > 50
Science, 2016
Carol Hua (ChemComm 53, , 2017) 7

8. First observation of flexibility
Sorption 401: What if sorbent changes structure?
Flexible porous materials can transform suddenly or gradually
1995
2005
2015
First observation of flexibility
S. Kitagawa
Bull. Chem. Soc. Jpn, 1998
MIL-53
G. Ferey, JACS, 2002
DMOF-1
Angew, 2004
MIL-88
Science, 2007
Co(bdp)
JACS, 2008, 2010
Nature, 2015
Nature, 2016
DUT-49 8

9. Natural gas (NG) storage
A virtual experiment suggests that rigid materials are unsuited
200cc/cc is the minimally needed working capacity for adsorbed NG at 70 atm
No porous material is yet close to the (DOE) targets for volumetric capacity and simulations on 650,000 compounds suggest that rigid porous materials are unlikely to meet the ARPA-E targets for working capacity
C. M. Simon, et al., Eng. Environ. Sci. 2015, 8, 1190. 9