Introduction of MoF compounds and comparison of statistical data of these compounds with zeolites.

1. 1

2. MOF, METAL-ORGANIC FRAMEWORKS:
A VERSATILE CLASS OF ADVANCED
MATERIALS
Presented by
Mahsa Ehsani nia
PhD ( Inorganic Chemistry)
RAZI Uni
Supervisor:
Dr. Mohammad Joshaghani
2

3. Title and Content Layout with List
› Introduction
– Nanoporous Materials ( What are?, and types)
› Review of Metal-Organic Frameworks
– Basic structure
– Structural features
– Important of pore size
– Preparation of MOFs
– Common ligands used for MOFs
– Properties of MOFs
– For better application
– Synthesis method
– Chemistry of MOFs
– Applications of MOFs
› Literature review
› Conclusion and Scope for future work for MOFs
3

4. › Consist of a regular organic or inorganic structure, supporting a periodic
porous system.
Nanoporous
materials
Microporous
(R<2nm)
Mesoporous
(2<R<50 nm)
Macroporous
(R>50 nm)
4

5. NANOPOROUS
ZEOLITES
MOFs
POFs
5

6. Zeolites are microporous crystalline solids with well-defined structures.
Generally they contain silicon, aluminium and oxygen in their framework
and cations, water and/or other molecules within their pores.
Zeolites form with many diffrenet crystalline structures, which have large
open pores ( sometimes referred to as cavities) in a very regular
arrangement and roughly the same size as small molecules.
The most interesting thing about zeolites is their open, cage-like
framework structure and the way it can trap other molecules inside it.
6

7. POFs are composed of different organic moieties linked by covalent
bonds, resulting in ordered and rigid structure.
Exceptional Thermal stabilities and low Frameworks Densities.
Exibit permanent porosity and specific surface areas.
Application: Gas storage, Separation, Catalysis and etc.
7

8. Metal-Organic Framework, abbreviated to MOF, is a Coordination Polymer
( or alternatively Coordination Network) with an open framework
containing potential voids.
MOFs are self-assembled metal clusters with organic ligands, are well
known for their structure, permanent porosity, and tunable properties and
have shown great prospect for various applications.
8

9. MOFs structures made up of inorganic nodes, which can either
be single ions or clusters of ions, and organic linkers.
9

10. They contain potential voids which can be used for various application.
Very low density
Crystalline
Large voids
Significant van der waals interaction
Complex unit cell
10

11. 1
• Many potential applications of MOFs depends on the size and nature
of the available free volume or pores within the frameworks
structure
2
• Tuning of the pores is typically achieved by variation of the metal
ions or organic ligands
3
• Lenghening the organic chains can lead to increased pore size but is
often limited by a decrease in stability of the framework.
11

12. 4
• With no gas present, the thermal conductivity decreases with increasing pore size. In
the presence of adsorbed gas, MOFs with smaller pores experience reduced thermal
conductivity due to phonon scattering introduced by gas crystal interactions.
5
• For larger pores (>1.7 nm), the adsorbed gas does not significantly affect thermal
conductivity.
6
• This difference is due to the decreased probability of gas-crystal collisions in larger
pore structures.
12

13. 13

14. 14
The coordination complex formed by the metal ions and the
donor atoms of the linker, termed the secondary building unit
(SBU), dicates the final topology of the MOF framework.

15. 15

16. The backbone of the compound is constructed from metal ions which act
as connectors and organic bridging ligands as linkers.
Readily accessible porosity.
The coexistence of inorganic ( hydrophilic) and organic ( hydrophobic)
moieties in structure may influence on adsorption properties.
Although most of MOFs are electrical insulators, several materials in this
class have recently demonstrated excellent electrical conductivity and
high charge mobility.
The thermal stability of MOFs is determined by the coordination number
and local coordination environment instead of framework topology
In general MOFs are poor thermal conductors with thermal conductivity
that is similar to concrete.
16

17. Surface Area: MOFs with higher surface area are more desirable.
Pore Size: MOFs must have the proper pore size to allow uptake and
release of analytes.
Stability: MOFs must exhibit reasonable stability upon exposure to
oxygen, moisture, the analytes of interest or changes in temperature.
Solubility: MOFs shoud be insoluble in aqueos media.
Analyte interaction: MOFs may exhibit special structural characteristics
that may facilitate selective uptake and release of analytes.
17

18. Different methods of synthesis of MOFs have been described:
I] non-solvothermal ( open flasks, below the solvent boiling point,
at atmospheric pressure)
A) Traditional synthesis:
II] Hydrthermal/solvothermal ( special closed chemical reactors, boiling
temperature of the solvent or above this boiling point, elevated
pressure caused by solvent vapour or produced by a pump.)
Notice: method I] dose not require complex equipment
method II] Solvothermal synthesis affords higher yields and better crystallinity of the
product.
but requires special equipment (autoclaves or sealed containers that
can withstand increased pressure); in addition, the duration of
the process should be taken into account (the synthesis can continue for
several weeks and even months).
18

19. I] microwave method
II] electrochemical method
III] mechano chemical method
B) Non-traditional methods:
IV] sono-chemical method
V] microemulsion method
19

20. But most of the time, MOFs are synthesized by combining organic ligands and
metal salts in solvothermal reactions at low temperatures (below 300°C),
that:
Polar solvent: Water, dialkyl formamides, dimethyl sulfoxide or acetonitrile.
The most important parameters of solvothermal: temperature, the source
and concentration of metal salt and ligand (which can be varied across a
large range), the solubility of the reactants in the solvent, the PH of the
solution, reaction time and etc.
20

21. The organic linkers used in MOFs are capable of connecting two metal oxide
clusters (ditopic linkers).
Linkers with higher dimensionality can also be used.
Organic ligands with rigid backbones are often preferred, because the rigidity
makes it easier to predict the network geometry, and in addition the rigidity
also helps to sustain the open pore structure after the removal of the included
solvent.
Transition metal ions are often used as the inorganic components of MOFs.
Different metal ions are well known to prefer different coordination numbers
and geometries, such as linear, T- or Y-shaped, tetrahedral, square-planar,
square-pyramidal, trigonal-bipyramidal, octahedral, trigonal-prismatic, and
pentagonal-bipyramidal.
The bonds formed between the metal ions and donor atoms of the linker are
strong and as a result, the extended network structure in the MOF is quite
robust.
21

22. Careful selection of MOF constituents can yield crystals of ultrahigh
porosity and high thermal and chemical stability. These characteristics
allow the interior of MOFs to be chemically altered for use in gas
separation, gas storage, and catalysis, among other applications.
Active sites on MOFs are located at the metal nodes, functional linker on
the crystalline structure and guest species; when the reaction occurs, the
framework protects their active sites and increases the efficiency.
22

23. By using appropriate system it possible to synthesis extended polymeric
structures. MOFs containing large spaces may result in the formation of
interpenetrating structures. Formation of interpenetrating networks can
be inhibited by choosing suitable organic ligands.
23

24. MOF
Gas separation
Gas adsorption
Gas purification
Catalysis
Hydrogen
storage
Bio-medical
App
Ion-
exchange
Sensor
materials
24

25. 25

26. 1. Number of publications on zeolites and MOFs:
26

27. 2. Population and representative researches in research countries:
zeolites
MOFs
27

28. 28
26%
13%
8% 7%
5%
3% 2%
3. Research area population
11%
7%

29. 29
37%
22%
11%
8% 7%
5%
2% 1% 1% 1%

30. 4. Next Classify of Research Domain for Zeolites and MOFs
We next classify the research domain using the four stages
defined in Scheme 2.
30

31. Figure 6 summarizes the percentages and representative large
domains for zeolites and MOFs. The research area for zeolites has
been focused on “properties” and “applications”, whereas that for
MOFs has been focused on “synthesis” and “applications”.
1
2
1 2
31

32. SYNTHESIS OF ZEOLITES:
Around 200 framework types of zeolites
have been synthesized and reported.
Primarily, zeolites have been
synthesized using hydrothermal
methods.
The lower number of framework
structures of zeolites is due to the low
number of building unites and mystery
in the self-assembly processes of
zeolites. In general, the synthesis of
new framework structures is difficult to
achieve.
SYNTHESIS OF MOFS:
The synthesis of new MOFs is widely studied
because of the variety in combinations of
metal ions and bridging ligands.
These structures are important with regard
to the surface area. Likewise, the
incorporation of functional building unites
basically allows their molecular functionality
to be adopted by porous materials.
Most of these are synthesized using
hydrothermal methods, along with
microwave or ionothermal synthetic
methods.
Interest in them is also due to their
topological structures, which are not found
in inorganic salt or molecular crystals.
32

33. PROCESS OF ZEOLITES
Processing in zeolite synthesis mainly
includes two topics: 1) synthesizing
zeolites from low-cost starting materials
and 2) control zeolite morphologies.
The starting materials for zeolites are
relatively cheap, with a cost of
approximately $200 to produce 1 kg of
typical zeolite Y.
For SiO2, using industrial wastes such as
coal fly ash and asbestos has been well
studied.
PROCESS OF MOFS
Processing of MOFs is a minor topic in this
research area. The chemicals needed for
syntheses, such as organic ligands and
solvents, are more expensive than the
building blocks for zeolites.
In case of MOF-5, which could be the most
famous class of MOFs, this cost is more than
$14,000 to produce 1 kg. This is because of
the requirement for expensive organic
solvents such as DMF and chloroform.
Industrial researchers are still investigating
the processing strategy. BASF started the
electrolysis of Cu for the synthesis of HKUST-1
[Cu3(btc)2]n (btc = 1,3,5-
benzenetricarboxylate), and some researchers
have started to use organic waste such as PET
bottles as a route for MOF syntheses.
33

34. PROPERTIES OF ZEOLITES
One of the most important properties of
zeolites is their acidity. Zeolites have
Brønsted acidic proton sites as
counterparts to anionic frameworks,
which can be introduced by the
isomorphous substitution of Si(IV) by
Al(III) atoms in the TO4/2 (T = Si, Al)
tetrahedral.
PROPERTIES OF MOFS
Adsorptive properties are tunable in terms
of pore functionalization. MOF-74
[M2(dobdc)]n (dobdc = 2,5-dioxido-1,4-
benzenedicarboxylate) can be synthesized
with a variety of metal centers such as Zn2+,
Ni2+, Mn2+, Co2+, and Fe2+.
The H2 adsorption heat is also tunable.
These tunabilities in relation to the
adsorption energy are particularly important
for gas separation based on interactions.
The flexibility of the framework is specific
for MOFs and has been shown as unique
porous properties. This is because such
porous materials change their structures in
response to guest adsorption, making these
materials useful for some applications. 34

35. APPLICATION OF ZEOLITES
Catalytic applications are more ideal for
zeolites because of the use of robust
frameworks and their acidic sites
compared with MOFs. Acidic sites
provide various organic reactivity such
as cracking and isomerization. Tons of
zeolites have been used for the fluid
catalytic cracking of heavy oils.
Redox active sites are introduced using
metal site substitutes such as Ti and Sn.
The redox activity can be used for
epoxidation, and so on.
Extra-framework cations such as Cu2+
and encapsulated clusters such as Pt
clusters can also be catalytic reaction
sites.
APPLICATION OF MOFS
Gas adsorption applications as portable
storage are more suitable for MOFs because
of the light composition of formula weights.
Hydrogen and methane gases are the general
targets for gas storage as a demonstration of
energy transport. Because of their high
surface area and strong interaction with
guest molecules, they already exceed the
theoretical limits for zeolites and carbon-
based materials.
Gas separation applications have also been
studied. Syn-gas can be contaminated with
CO2. Therefore, CO2/CH4 or C2H6/CH4
separation has been studied.
35

36. 5. Well-cited research areas from citation network analysis
high impact areas of research by analyzing what types of research areas are acceptable to
high-impact journals (HIJs) on average.
HIGH IMPACT AREAS OF RESEARCH FOR ZEOLITES HIGH IMPACT AREAS OF RESEARCH FOR MOFS
36

37. 6. Research area preferences by country
A. zeolites
Membrane reactor
Nanosheet-based catalysis
Cation exchange and the basic spectroscopic characterization of zeolites
Cation exchange and the basic spectroscopic characterization of zeolites
37

38. B. MOFs
Synthesis of MOFs
Gas storage
Catalysis, semiconductors and films
Synthesis of MOFs and battery-basedapplications
38

39.  The research area of zeolites has been application-oriented compared with that on
MOFs because of their solid acid and ion-exchange properties with robust frameworks.
Designable zeolite synthesis based on the physical properties and framework structures
will be a future challenge.
 On the other hand, research areas of MOFs are still being developed. Their structural
design ability leads to the control of physicochemical properties. Structural robustness
of MOFs will be required for the future development of industrial applications and
processes.
 Basically, the research areas classified as “application” in the zeolite area, such as
harsh catalytic reactions, have not been examined in the MOF area. Similarly, the
application areas for MOFs are seldom investigated in contrast to zeolites. This
tendency seems to reflect the longer research history for zeolites compared to MOFs,
with many studies in the “application” stage. Referring to the future applications of
zeolites will be beneficial for MOFs. Here, we propose possible research areas for
zeolites and MOFs, as listed.
39

40. 40