The Catalyst Review December 2019 - 11

frequently found in chemical manufacturing and food processing. While the synthesis
of numerous MOFs was demonstrated at laboratory scale, the synthesis recipes and
parameters were specifically revisited for HKUST-1 and ZIF-8 in an up-scale study in
the frame of the ProDIA program. The demonstration at scale one was carried out in
Axel'One (Figure 5), a collaborative platform, located in Lyon (France).

Figure 5. Pictures of the spray-drier demonstration unit at Axel'One, Lyon, France.

The ATEX certified platform is equipped with tools and large vessels specially conceived
for upscaling studies of solids, including organic containing solids. In particular, the
spray dryer pilot unit of 10m high and 2 m diameter has a daily capacity up to 50
kg. The pilot spray-drying tower is designed for scientific and industrial research
and development, as well as for small-scale production, especially for in the frame
of demonstration projects. It can operate in open (air) or closed (nitrogen) cycle
configurations. It is equipped with all kind of nozzles systems allowing adaptation to
different feeds and the control of aggregate size. Solvents are condensed, collected and
reinjected in the drying chamber.
A successful demonstration of HKUST-1 production based on ICN2 upscaling studies was
carried out in 2018. A precursor slurry of 158 kg has been sprayed within two hours. A
total of 18kg of HKUST-1 shaped grains was collected corresponding to a synthesis yield
of 99%wt with 95%wt of solvent recovery. The global space-time-yield was estimated
at 1.000 kg.m-3day-1. The powder as received was activated in oven at 150 °C under N2
flow in order to remove solvent trapped in the microporosity yielding high quality X-Ray
Diffraction pattern and a BET surface area above 1600 m2/g (Figure 6).
Water based synthesis process. MOFapps, Oslo University, and CNRS have developed
a water-based process for the synthesis of Zirconium pyromellitate also called UiO66-(COOH2) which belongs to the MOF family of UiO-66. Zirconium pyromellitate with
composition [Zr6O4(OH)8(H2O)4(Linker)4] was produced on a 650 L reflux reactor using
only water as solvent under reflux conditions. After filtration, washing with additional
water and drying, 128 kg of product have been obtained as white crystalline powder
(Figure 7). The powder was processed by extrusion to get 1mm pellets (see below)
which perform as commercial adsorbents for ammonia air purification for use in
protective filters (Khabzina et al. 2018).
Flow chemistry. Water based continuous synthesis of UiO-66 and other MOFs were
also demonstrated at relatively large laboratory scales using heated coiled as reactor
system (Rubio-Martinez et al. 2014). The startup MOFWORX from CSIRO Australia
is commercializing MOFs based on patented pressurized flowchem manufacturing
technology. The group have built a reactor called Mindi (the aboriginal name for
a mythological serpent that spits out white powder) that is capable of 10 kg h−1

Source: Axel'One.
Figure 6. Collection of HKUST-1 powder at the
bottom of the Axel'One spray-dryer.

Source: Axel'One.
Figure 7. 128kg of UiO-66 obtained in a single
batch aqueous synthesis.

Source: Axel'One.

Progress in MOF Shaping Using Mature and New Technologies

Although extrusion and granulation processes are well-established mature shaping technologies, MOF extrusion and granulation
at industrial scale are missing until now possibly due to challenges linked to their intrinsic fragility. Limitations can be listed into
three categories: (1) relatively low thermal stability preventing the use of classical shaping processes which are based on firing a
binder-containing formulation after pelletization; (2) for some MOFs low chemical stability in water, making extrusion processes not
generalizable; and (3) relatively lower mechanical stability owing to their very high porosity, leading to structural collapsing when the
applied pressure exceeds a given threshold.
Mild tableting by compression appears to be a practical solution for MOFs as it overcomes firing issues and the use of solvent.
The use of binders such as alumina, silica, graphite, or polyvinyl alcohol was reported to limit structure degradation observed
when even moderate strengths are applied, but they also decrease the tablets overall porosity proportionally. The optimization of
MOFs densification consists in finding a compromise between a gain in mechanical stability of the body versus a loss of their initial
properties. Ideally, structural and textural properties of the MOF crystals should be preserved while the tablets density and hardness
should be as high as possible, owing to the "plastic" properties of MOFs, CNRS presented a systematic study on MOF powders
The Catalyst Review 										

December 2019



The Catalyst Review December 2019

Table of Contents for the Digital Edition of The Catalyst Review December 2019

The Catalyst Review December 2019 - cover
The Catalyst Review December 2019 - contents
The Catalyst Review December 2019 - 1
The Catalyst Review December 2019 - 2
The Catalyst Review December 2019 - 3
The Catalyst Review December 2019 - 4
The Catalyst Review December 2019 - 5
The Catalyst Review December 2019 - 6
The Catalyst Review December 2019 - 7
The Catalyst Review December 2019 - 8
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The Catalyst Review December 2019 - 11
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The Catalyst Review December 2019 - 16
The Catalyst Review December 2019 - 17
The Catalyst Review December 2019 - 18