Chemical Engineering December 2018 - 6

CTL processes.
By eliminating CO2 production
in the F-T step, all of
the CO2 produced by a CTL
process takes place in the
water-gas-shift (WGS) reactor,
thereby generating a concentrated
CO2 stream, which
is important for carbon-capture
and storage or utilization
strategies, according to the
researchers, who reported
their findings last month in
Science Advances.
The Sino-Dutch research
team discovered that the CO2
released in the F-T synthesis
is caused by the fact that the
Fe-based catalysts are not
pure, but consist of several
components. They were able
to produce a pure form of
epsilon
iron carbide, which
has a very low CO2 selectivity.
Although the existence of
ε(')-Fe2C had already been
known, the material had not
been stable enough for the
harsh conditions used in the
F-T synthesis. The Sino-Dutch
research team has now shown
that this instability is caused
by impurities in the catalyst.
The phase-pure ε(')-Fe2C is
said to be stable and remains
functional, even under typical
industrial process conditions
(23 bars and 250°C).
By eliminating nearly all CO2
generated in the F-T reactor,
less energy is required, which
reduces operating costs by
roughly €25 million/yr for a
typical CTL plant, according
to TUE.
(Continues on p. 9)
Ammonia synthesized from renewable
power and hydrogen
A
collaboration between
JGC Corp. (JGC, Yokohama,
Japan; www.
jgc.com), the National
Institute of Advanced Industrial
Science and Technology
(AIST), the National Institute
of Technology, Numazu College,
and JGC's subsidiary,
JGC Catalysts & Chemicals
Ltd., (JGC Group), under the
auspices of the cross ministerial
strategic innovation promotion
program (SIP), " Energy
Carriers, " announced that its
joint study has resulted in the
world's first success in the
synthesis of NH3 using H2 produced
through the electrolysis
of water by renewable energy,
and generation of electricity
through gas turbines fueled by
synthesized NH3.
Last May, JGC Group achieved success
in development of a new ruthenium catalyst
supported by rare earth oxide (Ru/REO2),
which is capable of efficiently synthesizing
ammonia at a low (300-400°C) temperature
and low pressure (5-8 MPa), which is
far milder than the 400-500°C and 14-30
MPa used for an iron-based Haber-Bosch
process. The REO-supported Ru catalyst is
said to have " excellent stability " compared
to Ru catalysts that utilize carbon-based
carriers. JGC began operating a demonstration
plant - located at Fukushima Renewable
Energy Institute, AIST in Koriyama
City, Fukushima Prefecture - that is capable
of producing 20 kg/d of NH3. Initial
testing of the new catalyst used high-purity
C
6
urrent oil-water separation
technologies, such as centrifugation,
filtration, dissolved
air flotation,
JGC
New ammonia production process
Air
Electrolysis of water
Renewable energy
* Photovoltaic
* Solar power
* Wind power
* Hydroelectric
Fossil fuels
Reforming/
gasification
* Natural gas
* Oil
* Coal
H2
Catalyst
N2
Air
CO2
hydrogen from gas cylinders.
JGC Group has verified the ability of handling
rapid changes in operational conditions
when using renewable energy. Now,
the group has replaced the bottled H2 supply
with H2 generated by solar-powered
water electrolysis to make ammonia, which
then fueled a gas turbine to generate electric
power (47 kW).
This is claimed to be the first time renewable
H2 has been used to make NH3 that is
subsequently used for CO2-free power generation.
The achievement is a step toward
the vision promoted by SIP Energy Carriers
research of " Japan creating an innovative
low-carbon, hydrogen-fueled economy and
taking the lead in hydrogen-related industries
on the world market " by the year 2030.
MOF-coated mesh membranes separate oil from water
distillation,
oil skinners, adsorption and
electrochemical methods, are of low
efficiency and consume a lot of energy
during complex separation processes.
Mesh membranes have attracted
much interest lately, and some
polymers have been successfully applied
onto mesh membranes. However,
due to their oleophilic properties,
the surfaces of those membranes are
easily polluted or even blocked by oil.
Now, a ZIF-8-coated mesh membrane
for high-efficiency oil-water
separation has been prepared by a
team from Jilin University (Changchun,
China; www.jlu.edu.cn) and Sinopec
Institute of Safety Engineering (Qingdao,
China; www.sinopec.com). ZIFs
- zeolite imidazole frameworks - are
a subfamily of metal organic frameworks
(MOFs) that exhibit various topologies
and morphologies, and are
chemically and thermally fairly stable.
The membranes have micro- and
nano-scale architectures, and are
fabricated by simply immersing mesh
into a precursor solution at room
temperature and atmospheric pressure.
Water molecules are imbibed
into a rough solid surface to form a
barrier layer that produces a strong
repulsive force to an oil droplet, which
makes the membranes exhibit underwater
superoleophobicity. The membranes
are also highly stable at high
temperatures and after exposure to
various organic solvents. Due to its
facile fabrication, the membrane can
be easily enlarged, which is critical for
oil-water separation.
According to the team, the ZIF-8
coated mesh membranes exhibit high
water flux (10.2 × 104 L/m2/h) and
achieve a separation efficiency better
than 99.99% for various oil-water mixtures,
with the residual oil content in
the collected water less than 4 ppm.
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
DECEMBER 2018
Haber-Bosch process
High temperature/
high pressure
Ammonia
O2
N2
Low pressure/
low temperature
Catalyst
H2O
H2
Ammonia
http://www.jgc.com http://www.jlu.edu.cn http://www.sinopec.com http://WWW.CHEMENGONLINE.COM
Chemical Engineering December 2018

Table of Contents for the Digital Edition of Chemical Engineering December 2018
