fast but unprecedentedly selective for the olefin/paraffin separation [62, 123,
124]. Although the prominent adsorbents in terms of olefin capacity and selectivity
are MOFs, they need open metal sites on which to adsorb olefin molecules, increasing the cost. In this regard, heteroatom-substituted or exchanged zeolites hold the
same, if not greater, potential to separate hydrocarbon mixtures, as demonstrated
using FeAl-LEV and Ag-LTA [81, 102]. We have also noted that zeolites and related
crystalline microporous materials are desirable over other materials like MOFs or
ACs, in terms of the cost, industrial applicability, and stability [4]. Furthermore,
zeolites can outperform some MOFs with respect to selectivity as well as showing
relatable adsorption kinetics [107]. Nevertheless, however, the preparation of
zeolite-MOF composite materials can in our view lead to an enhancement of the
adsorption capacity, selectivity, or both. This can be supported by a very recent study
on the CH 4 /N 2 separation using ZIF/Zn-Y and ZIF/Zn-ZSM-5 hybrid adsorbents,
where an increase in selectivity relative to its constituents is observed [125].
Apart from the current research motivations in the small gas adsorption field, such
as climate change mitigation, environmentally friendly catalysis, and capture/separation of poisonous and noble gases, among others, it would be wise if zeolite
researchers start to consider how current and future framework types may be adapted
or utilized in the future hydrogen economy. For example, current zeolite materials
are not suited for hydrogen storage, yet they seem highly functional for separation of
hydrogen from gas mixtures, as well as its deuterium isotope [126]. With this is
mind, we expect that many small-pore zeolitic materials with new framework
structures and/or compositions and their composite materials will certainly be
discovered in the near future and then applied in existing gas adsorption and
separation equipment without the need for refurbishing. We also anticipate that
both new and existing zeolites will be synthesized in a more environmentally benign
manner.
Acknowledgments We acknowledge financial support from the National Creative Research
Initiative Program (2012R1A3A2048833) through the National Research Foundation of Korea.
References
1. Colella C, Gualtieri AF (2007) Cronstedt’s zeolite. Microporous Mesoporous Mater
105:213–221
2. Eldridge RB (1993) Olefin/paraffin separation technology: a review. Ind Eng Chem Res
32:2208–2212
3. Patel HA, Byun J, Yavuz CT (2017) Carbon dioxide capture adsorbents: chemistry and
methods. ChemSusChem 10:1303–1317
4. D’Alessandro DM, Smit B, Long JR (2010) Carbon dioxide capture: prospects for new
materials. Angew Chem Int Ed 49:6058–6082
5. Shin J, Jo D, Hong SB (2019) Rediscovery of the importance of inorganic synthesis parameters in the search for new zeolites. Acc Chem Res 52:1419–1427
6. Foster MD, Treacy MMJ. Atlas of prospective zeolite structures. http://www.
hypotheticalzeolites.net/. Accessed 29 Nov 2019
24
K. C. Kemp et al.
124]. Although the prominent adsorbents in terms of olefin capacity and selectivity
are MOFs, they need open metal sites on which to adsorb olefin molecules, increasing the cost. In this regard, heteroatom-substituted or exchanged zeolites hold the
same, if not greater, potential to separate hydrocarbon mixtures, as demonstrated
using FeAl-LEV and Ag-LTA [81, 102]. We have also noted that zeolites and related
crystalline microporous materials are desirable over other materials like MOFs or
ACs, in terms of the cost, industrial applicability, and stability [4]. Furthermore,
zeolites can outperform some MOFs with respect to selectivity as well as showing
relatable adsorption kinetics [107]. Nevertheless, however, the preparation of
zeolite-MOF composite materials can in our view lead to an enhancement of the
adsorption capacity, selectivity, or both. This can be supported by a very recent study
on the CH 4 /N 2 separation using ZIF/Zn-Y and ZIF/Zn-ZSM-5 hybrid adsorbents,
where an increase in selectivity relative to its constituents is observed [125].
Apart from the current research motivations in the small gas adsorption field, such
as climate change mitigation, environmentally friendly catalysis, and capture/separation of poisonous and noble gases, among others, it would be wise if zeolite
researchers start to consider how current and future framework types may be adapted
or utilized in the future hydrogen economy. For example, current zeolite materials
are not suited for hydrogen storage, yet they seem highly functional for separation of
hydrogen from gas mixtures, as well as its deuterium isotope [126]. With this is
mind, we expect that many small-pore zeolitic materials with new framework
structures and/or compositions and their composite materials will certainly be
discovered in the near future and then applied in existing gas adsorption and
separation equipment without the need for refurbishing. We also anticipate that
both new and existing zeolites will be synthesized in a more environmentally benign
manner.
Acknowledgments We acknowledge financial support from the National Creative Research
Initiative Program (2012R1A3A2048833) through the National Research Foundation of Korea.
References
1. Colella C, Gualtieri AF (2007) Cronstedt’s zeolite. Microporous Mesoporous Mater
105:213–221
2. Eldridge RB (1993) Olefin/paraffin separation technology: a review. Ind Eng Chem Res
32:2208–2212
3. Patel HA, Byun J, Yavuz CT (2017) Carbon dioxide capture adsorbents: chemistry and
methods. ChemSusChem 10:1303–1317
4. D’Alessandro DM, Smit B, Long JR (2010) Carbon dioxide capture: prospects for new
materials. Angew Chem Int Ed 49:6058–6082
5. Shin J, Jo D, Hong SB (2019) Rediscovery of the importance of inorganic synthesis parameters in the search for new zeolites. Acc Chem Res 52:1419–1427
6. Foster MD, Treacy MMJ. Atlas of prospective zeolite structures. http://www.
hypotheticalzeolites.net/. Accessed 29 Nov 2019
24
K. C. Kemp et al.