Tech Briefs Magazine - May 2021 - 44

Manufacturing & Prototyping
Catalyst Makes Styrene Manufacturing Cheaper and Greener
This could reduce the environmental impact of styrene manufacturing.
North Carolina State University, Raleigh

hemical engineering researchers have
developed a new catalyst that significantly increases yield in styrene manufacturing, while simultaneously reducing
energy use and greenhouse gas emissions. Styrene is a synthetic chemical that
is used to make a variety of plastics, resins,
and other materials. Industry estimates
predict that manufacturers will be producing more than 33 million tons of
styrene each year by 2023.
Conventional styrene production
technologies have a single-pass yield of
about 54%. In other words, for every 100
units of feedstock put into the process, it
would yield 54 units of styrene out of
each pass. Using the new catalyst, the
researchers were able to achieve a singlepass yield of 91%.
The conversion process takes place at
500 to 600 °C - the same temperature
range as conventional styrene manufacturing processes. Current techniques require injecting very large volumes of
steam into the reactor where the conver-

Ethylbenzene + [O]

Styrene + H2O

Redox Catalyst

Catalytic Shell
2eO2-

O2-

Toluene Benzene
2.6% 1.1%
0.2% CO2
1.9% C

Styrene Selectivity
94.2%

storage Core
91.4% single pass yield

Conventional styrene production technologies have a single-pass yield of about 54%. For every 100
units of feedstock put into the process, it yields 54 units of styrene out of each pass. Using the new
catalyst, researchers were able to achieve a single-pass yield of 91%.

sion takes place. The new technique
requires no steam. In practical terms, this
drastically reduces the amount of energy
needed to perform the conversion.
Specifically, the conversion process that
incorporates the new catalyst uses 82%
less energy and reduces carbon dioxide
emissions by 79%.
The new redox catalyst has a potassium
ferrite surface for the catalytic phase and

a mixed calcium manganese oxide core
for lattice oxygen storage. In order to
adopt the new catalyst, styrene manufacturers would need to adopt a different
style of reactor than they are currently
using but the cost savings from the new
process should be significant.
For more information, contact Matt
Shipman at matt_shipman@ncsu.edu; 919515-6386.

3D Printing of Gels and Soft Materials
A new method could jump-start the creation of tiny medical devices for the body.
National Institute of Standards and Technology, Gaithersburg, Maryland

esearchers have developed a new
method of 3D-printing gels and other
soft materials that has the potential to create complex structures with nanometerscale precision. Because many gels are
compatible with living cells, the new
method could jump-start the production
of soft, tiny medical devices, such as drug
delivery systems or flexible electrodes, that
can be inserted into the human body.
A standard 3D printer makes solid structures by creating sheets of material - typically plastic or rubber - and building
them up, layer by layer, until the entire
object is created. In the standard method,
the 3D printer chamber is filled with longchain polymers - long groups of molecules bonded together - dissolved in
water. Then, special molecules that are

sensitive to light are added. When light
from the 3D printer activates those special
molecules, they stitch together the chains
of polymers so that they form a fluffy, weblike structure. This scaffolding, still surrounded by liquid water, is the gel.
Typically, modern 3D gel printers use
ultraviolet or visible laser light to initiate
formation of the gel scaffolding; however,
the researchers focused their attention on
a different 3D-printing technique to fabricate gels using beams of electrons or Xrays. Because these types of radiation have
a higher energy, or shorter wavelength,
than ultraviolet and visible light, these
beams can be more tightly focused and
therefore produce gels with finer structural detail. Such detail is exactly what is
needed for tissue engineering and many

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other medical and biological applications.
Electrons and X-rays offer a second advantage: They do not require a special set of
molecules to initiate the formation of gels.
At present, the sources of this tightly
focused, short-wavelength radiation -
scanning electron microscopes and X-ray
microscopes - can only operate in a vacuum where the liquid in each chamber
evaporates instead of forming a gel. The
researchers demonstrated 3D gel printing
in liquids by placing an ultrathin barrier
- a thin sheet of silicon nitride -
between the vacuum and the liquid chamber. The thin sheet protects the liquid
from evaporating (as it would ordinarily
do in vacuum) but allows X-rays and electrons to penetrate into the liquid. The
method enabled the team to use the 3D
Tech Briefs, May 2021

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Tech Briefs Magazine - May 2021

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