ABSTRACT
Porous zeolitic materials are one of the most premising categories
of materials particularly for application in separation, purification,
and catalytic processes. Nowadays, crystalline microporous zeolitic
materials contribute to a very large segment of the global economy
(>$350 billion). They are utilized in a wide range of applications
in different industries such as petrochemical, detergent, water
and wastewater treatment purification, and gas separation and
storage. Recently, extensive research has been focused on using
the molecular building block approach to synthesize 3D metal-
organic frameworks (MOFs). Metal-ligand coordination strategies
are used to link the molecular components for construction of
these porous compounds. A number of such frameworks have been
found to exhibit desirable zeolitic properties such as microporosity
of the framework, extraordinary adsorption, and selective catalytic
activity. Thesematerials generally consist ofmetal-oxygen ormetal-
nitrogen polyhedra containing divalent (e.g., Zn2+, Cu2+) or trivalent (e.g., Al3+, Cr3+) cations. Metal cations interconnected with a variety of organic linker molecules result in tailored nanoporous materials.
With appropriate choice of linkers, it is possible to fine-tune the
size, shape, and chemical functionality of materials to improve
the properties. This unique structural feature offers revolutionary
opportunities in H2 storage, CH4 and CO2 separation and storage,
chemical sensors, chiral pharmaceutical synthesis and separation,
and catalysis. The zeolitic-like framework organometallic materials
are similar to zeolites in many aspects such as high crystallinity,
tunable hydrophil(phob)icity, and acid(basic)ity. They are, however,
different in many other aspects such as higher surface area/pore
volume (up to 6000-9000m2/g in comparison to 200-900m2/g for
zeolites) andmuchmore diverse chemistry (e.g., manymetals/metal
clusters and organic linkers can contain functionality). Despite the
abovementioned extraordinary capabilities of MOFs, particularly for
H2 and CO2 storage, one of the main obstacles toward commercial
application of the materials is relatively high expense of the final
product because of their costlymanufacturing process. Conventional
approaches for synthesis of MOFs are very expensive because of
high-energy consumption (e.g., typical synthesis might takes several
hours or days at high temperature of 100◦C-250◦C) and expensive organic linkers and solvents. Therefore development of a novel
synthesis process by means of a new energy source, such as
microwaves (MWs) and ultrasound, to decrease the crystallization
time (seconds or minutes) and to remarkably reduce the energy
consumption for the highly efficient manufacturing of MOFs in a
techno-economically viable manner is very desirable.
