Chemical Engineering January 2022 - 8

in Revivo BioSystems Pte.
Ltd. (Singapore; www.
revivobio.com) - a spinoff
of A*Star (Agency for
Science, Technology
and Research) - to support
the development
and commercialization of
a technology that uses
a realistic 4D model of
human skin for the testing
of
chemical,
cosmetic
and pharmaceutical
compounds. Revivo
BioSystems'
technology
provides an alternative to
animal testing that is also
quicker, more reliable and
cost efficient.
Revivo's organ-on-achip
system simulates
the interaction of human
skin with the substance
being
tested.
Skin
tissues,
which have been
grown in a laboratory or
a human skin sample, are
placed on biochips that
are supplied with nutrients
and reagents. In this way,
the technology creates a
micro-environment for the
tissue models, which reproduce
the architecture
and functions of skin. The
system also automates
testing and sampling procedures,
enabling screenings
that are required for
regulatory approval of
new substances. ❐
Bifunctional catalyst enables economically viable
production of bio-based acrylates
T
he prospects for a
bio-based route to
acrylates (diagram)
received a significant
boost recently, when
startup company Låkril
Technologies Corp. (Chicago,
Ill.; www.lakril.com) licensed
technology from the laboratory of Paul
Dauenhauer at the University of Minnesota
(Minneapolis, Minn.; twin-cities.umn.edu).
Dauenhauer has invented a catalyst said
to be the first in the world capable of generating
yields greater than 90% in the dehydration
reaction of lactate to acrylate. Previous
efforts to catalyze the reaction typically
achieve yields of only 50-60% - too low to
make the transformation an economically
viable alternative to the petroleum-based
route to acrylic acid (which is accomplished
by the oxidation of propylene).
Låkril has obtained funding to scale up
production of the catalyst and further develop
the technology for commercial use.
The company plans to start commercial production
in late 2024.
The catalyst under development is an
acidic solid zeolite (aluminosilicate) that
has been functionalized with an engineered
amine. The rationale for adding functionalization
came out of previous mechanistic
studies of the dehydration reaction. When
lactate comes into contact with zeolite, dehydration
or decarbonylation can occur, explains
Chris Nicholas, co-founder and presLåkril
Technologies
ident of Låkril. The amine functionalization
on the zeolite suppresses side reactions,
including the primary one - decarbonylation,
he says. The nature of the functionalized
catalyst is proprietary, but is proposed
to work wherein a base out-competes the
weaker oxygenated functional groups on
lactate, resulting in a higher coverage of
base than lactate on Brønsted acid sites
generated during reaction.
A technoeconomic analysis of the lactate
dehydration process suggests that by
suppressing side reactions and generating
higher yields of acylate, the reaction moves
into cost parity with the petroleum-based
route, while reducing carbon intensity by at
least 35%, Nicholas says.
Acrylates are industrially important for a
range of products, including superabsorbent
polymers in diapers, and as precursors
for esters used in fibers, paints, adhesives
and other products. With this new catalyst
development, making more environmentally
benign bio-based acrylates - by fermenting
corn sugars into lactic acid, then dehydrating
the lactic acid to acrylate - becomes
economically attractive.
Bulk polymerization of elemental sulfur yields
new flame-retardant plastics
A
8
group of researchers from the University of Arizona
(Tucson; www.arizona.edu), led by chemistry
and biochemistry professor Jeff Pyun, are
aiming to make use of sulfur waste streams
from petroleum refineries. To meet environmental regulations,
sulfur must be removed from crude oil during
refining, but economic end-uses for high-volume sulfur
streams are very limited.
" Typically, sulfur is very challenging to work with, as
it is insoluble in most solvents and difficult to work with
as a solid. Rather than trying to dissolve it, we developed
a new process to melt elemental sulfur and use it
as a monomer for polymerization, " explains Pyun. The
group developed a process called inverse vulcanization
that uses sulfur as both the monomer and the salt for
the polymerization reaction, resulting in a polymer with
a sulfur-based backbone. Initially, the group looked at
using the polymers in battery electrodes or optics materials,
but they also wanted to investigate higher-volume
end products, such as polyurethanes. To do so, Pyun's
group split the polymerization process into steps, first
starting with a prepolymer that is reacted with an olefin
that carries an alcohol group, forming a high-sulfur-content
precursor for segmented polyurethane products.
" We're taking very inexpensive materials, such as sulfur
and the alcohol 1-undecanol, and using them to make
conventional plastics, " adds Pyun.
These new sulfur-based polymers provided a valuable
benefit over traditional polymers - flame retardancy.
Typically, flame-retardant polymers involve either the addition
of specialty monomers to conventional plastics,
which drive up costs and inhibit large-scale production;
or the addition of small-molecule flame-retardant agents,
which are typically heavily halogenated, and introduce
serious environmental concerns. The new sulfur-based
polymers could unlock a pathway to cheaper, more sustainable
flame retardants, says Pyun, noting that there
are currently no similar products on the market. " I anticipate
this chemistry should be scalable, as the materials
and methods are inexpensive. The technology is also
quite modular. We've chosen polyurethanes, but other
polymers could certainly be made, " adds Pyun.
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
JANUARY 2022
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Chemical Engineering January 2022

Table of Contents for the Digital Edition of Chemical Engineering January 2022
