Nanoporous Polymeric Membranes for Hydrogen Separation
363
Way 2002). Platinum (Pt) is one more metal which is used as a spare filler material
for palladium (Patel and Acharya 2018). Both Pt and Pd also used with Ni, Ag, Au,
and Cu as alloy metals in composite membranes. The performance, fundamental
concept, and mechanism for the metallic membranes for gas separation have been
explained by many researchers (Moss et al. 1998; Ward and Dao 1999).
Due to some of the limitations with the metallic membranes, silica composite
membranes are an alternative approach for H 2 separation application. Compared to
metallic membranes; silica membranes are easy to fabricate, have controllable filler
porosity, and low cost of production. Silica has pores network matrix in which the
approximate diameter of the pore is 0.5 nm. Such small pores can control permeation
of the small gas molecules such as H 2 , CO 2 , He, CO, O 2 , and N 2 . Such type of composite membranes is not 100% selective for an individual component (Ghasemzadeh
et al. 2017; Nwogu et al. 2016). The separation of gas mixtures is centered on a competitive process of different molecules moving in the micropores network (Verweij
2003). Commonly two types of synthesis methods are used for silica-based composite membranes; chemical vapor deposition (CVD) and sol–gel method (Khatib and
Oyama 2013). In a comparison of both methods, sol–gel provides good permeability
as well as selectivity. While the problem with the sol–gel method is reproducibility
of the samples which can be achieved by CVD method by the controlled condition
of deposition.
For the last few years, zeolite membranes have achieved considerable attention in
the field of gas separation (Kosinov et al. 2016; Wee et al. 2008). Zeolite membranes
have controlled pore shape and size with the enhanced properties of mechanical,
thermal, and chemical stability. Such types of membranes have a long lifetime and
can be used multiple times. The optimized thickness of the zeolite membranes is
the key parameter for the selectivity and permeability data. Zeolites have uniform
and molecular-sized pores with crystalline inorganic nature. Most of the zeolites are
made with the TO 2 unit, where T represents a tetrahedral framework atom (Si, Al,
B, Ge, etc.) (Koohsaryan and Anbia 2016).
The long lifetime, stability at high temperature, and the ability of the regeneration makes these membranes a competitive candidate for H 2 separation/purification
application.
5.2 Carbon-Based Membranes
In the comparison with other materials, the composite material of carbon with polymer has been the center of demand due to their unique properties and technological
usage, especially for gas separation application (Haider et al. 2018; Hamm et al.
2017; Ismail and David 2001). Carbon-based polymer composites such as carbon
nanotubes (CNTs), graphite, graphene, graphene oxide (GO) have been reported
widely.
363
Way 2002). Platinum (Pt) is one more metal which is used as a spare filler material
for palladium (Patel and Acharya 2018). Both Pt and Pd also used with Ni, Ag, Au,
and Cu as alloy metals in composite membranes. The performance, fundamental
concept, and mechanism for the metallic membranes for gas separation have been
explained by many researchers (Moss et al. 1998; Ward and Dao 1999).
Due to some of the limitations with the metallic membranes, silica composite
membranes are an alternative approach for H 2 separation application. Compared to
metallic membranes; silica membranes are easy to fabricate, have controllable filler
porosity, and low cost of production. Silica has pores network matrix in which the
approximate diameter of the pore is 0.5 nm. Such small pores can control permeation
of the small gas molecules such as H 2 , CO 2 , He, CO, O 2 , and N 2 . Such type of composite membranes is not 100% selective for an individual component (Ghasemzadeh
et al. 2017; Nwogu et al. 2016). The separation of gas mixtures is centered on a competitive process of different molecules moving in the micropores network (Verweij
2003). Commonly two types of synthesis methods are used for silica-based composite membranes; chemical vapor deposition (CVD) and sol–gel method (Khatib and
Oyama 2013). In a comparison of both methods, sol–gel provides good permeability
as well as selectivity. While the problem with the sol–gel method is reproducibility
of the samples which can be achieved by CVD method by the controlled condition
of deposition.
For the last few years, zeolite membranes have achieved considerable attention in
the field of gas separation (Kosinov et al. 2016; Wee et al. 2008). Zeolite membranes
have controlled pore shape and size with the enhanced properties of mechanical,
thermal, and chemical stability. Such types of membranes have a long lifetime and
can be used multiple times. The optimized thickness of the zeolite membranes is
the key parameter for the selectivity and permeability data. Zeolites have uniform
and molecular-sized pores with crystalline inorganic nature. Most of the zeolites are
made with the TO 2 unit, where T represents a tetrahedral framework atom (Si, Al,
B, Ge, etc.) (Koohsaryan and Anbia 2016).
The long lifetime, stability at high temperature, and the ability of the regeneration makes these membranes a competitive candidate for H 2 separation/purification
application.
5.2 Carbon-Based Membranes
In the comparison with other materials, the composite material of carbon with polymer has been the center of demand due to their unique properties and technological
usage, especially for gas separation application (Haider et al. 2018; Hamm et al.
2017; Ismail and David 2001). Carbon-based polymer composites such as carbon
nanotubes (CNTs), graphite, graphene, graphene oxide (GO) have been reported
widely.