zeolite synthesis, most of the recent research is devoted to applications of zeolites,
while less than 10% is dedicated to the investigation or improving of the zeolitic
synthesis routes.
Contrary, almost 40% of MOF’s research works deal with their associated
synthesis, while the works dedicated to their applications are significantly lower
than in the case of zeolites. In the last case, it is noteworthy to mention that very
often, the studies dealing with the potential applications of MOFs in separation
technology are focused on benchmarking their performances versus the actually
implemented adsorbents (mainly zeolites but not only). The fact that MOFs present
some intrinsic limitations in terms of cost and hydrothermal stability diminishes the
success probability. Contrary to the case of the major zeolites (the more commercialized), the reactants involved in the synthesis of MOFs are significantly more
expensive than the silica-alumina sources employed in zeolite manufacturing.
Finally, only a limited number of MOFs offer the hydrothermal stability necessary
to face industrial operation conditions.
In order to correct for this bias, the selection of applications presenting associated
high-added values seems crucial. The other way around, the experience accumulated
in the tailoring of the new MOFs structures could be partially transposed to zeolites
potentially leading to new breakthroughs for zeolites. Designing virtual framework
structures based on a set of desired physical properties can be a future challenge for
the family of zeolites.
4 Main Industrial Separative Applications
After detergents (%70%) and catalysis (%15%), the use of synthetic zeolites for
adsorption constitutes the third main application (%15%) in terms of production.
Since the energetic cost of the unit operations associated with separation processes
represents the main part of a given industrial application [6], the correct choice of
separation techniques becomes central. Molecular sieving or adsorption-based separation techniques are placed among those presenting the lowest costs. This fact is
mainly explained by the process reversibility leading to higher efficiencies than
those associated with other conventional separation processes. Indeed, highly
engineered distillation towers present overwhelming energy consumptions when
compared to the thermodynamic limit [7]. Adsorption processes are then receiving
increasingly more attention, and high surface area materials with high specificity for
target molecules are continuously being developed. As a result, adsorption is applied
in several industrial domains from refining and petrochemicals to fine chemistry.
In spite of the mentioned advantages associated with adsorptive processes, the
choice between conventional distillation and other more disruptive technologies
such as liquid-liquid extraction, absorption, membrane separation, or adsorption is
far from being evident [8]. Indeed, the debate is often driven by the assumptions
established about the ratio between the costs of energy and capital. Similarly, the
origin of the energy employed in alternative techniques (such as the pumping energy
Industrial Zeolite Applications for Gas Adsorption and Separation Processes
201
while less than 10% is dedicated to the investigation or improving of the zeolitic
synthesis routes.
Contrary, almost 40% of MOF’s research works deal with their associated
synthesis, while the works dedicated to their applications are significantly lower
than in the case of zeolites. In the last case, it is noteworthy to mention that very
often, the studies dealing with the potential applications of MOFs in separation
technology are focused on benchmarking their performances versus the actually
implemented adsorbents (mainly zeolites but not only). The fact that MOFs present
some intrinsic limitations in terms of cost and hydrothermal stability diminishes the
success probability. Contrary to the case of the major zeolites (the more commercialized), the reactants involved in the synthesis of MOFs are significantly more
expensive than the silica-alumina sources employed in zeolite manufacturing.
Finally, only a limited number of MOFs offer the hydrothermal stability necessary
to face industrial operation conditions.
In order to correct for this bias, the selection of applications presenting associated
high-added values seems crucial. The other way around, the experience accumulated
in the tailoring of the new MOFs structures could be partially transposed to zeolites
potentially leading to new breakthroughs for zeolites. Designing virtual framework
structures based on a set of desired physical properties can be a future challenge for
the family of zeolites.
4 Main Industrial Separative Applications
After detergents (%70%) and catalysis (%15%), the use of synthetic zeolites for
adsorption constitutes the third main application (%15%) in terms of production.
Since the energetic cost of the unit operations associated with separation processes
represents the main part of a given industrial application [6], the correct choice of
separation techniques becomes central. Molecular sieving or adsorption-based separation techniques are placed among those presenting the lowest costs. This fact is
mainly explained by the process reversibility leading to higher efficiencies than
those associated with other conventional separation processes. Indeed, highly
engineered distillation towers present overwhelming energy consumptions when
compared to the thermodynamic limit [7]. Adsorption processes are then receiving
increasingly more attention, and high surface area materials with high specificity for
target molecules are continuously being developed. As a result, adsorption is applied
in several industrial domains from refining and petrochemicals to fine chemistry.
In spite of the mentioned advantages associated with adsorptive processes, the
choice between conventional distillation and other more disruptive technologies
such as liquid-liquid extraction, absorption, membrane separation, or adsorption is
far from being evident [8]. Indeed, the debate is often driven by the assumptions
established about the ratio between the costs of energy and capital. Similarly, the
origin of the energy employed in alternative techniques (such as the pumping energy
Industrial Zeolite Applications for Gas Adsorption and Separation Processes
201