Chemical Engineering March 2014 - 12

ChementatoR
(Continued from p. 11)
This pathway from cellulose to p-xylene
eliminates saccharification step
A
new chemical process is set to create
bio-based p-xylene from cellulosic
waste. Micromidas (West Sacramento,
Calif.; www.micromidas.com) opened a
pilot plant in December 2013 that converts
cellulosic waste materials, such as
rice hulls, switchgrass, sawdust and cardboard
to bio-based p-xylene.
The Micromidas process is unusual in
that it does not require the cellulose to be
saccharified first, and both cellulose and
glucose can be used as feedstock, with
similar yields. In the first reaction step,
cellulose is hydrolyzed and dehydrated
to 2,5-chloromethylfurfural (CMF). In a
subsequent reduction step, the CMF is
reduced to dimethylfuran - typically,
these sorts of reactions are hindered by
the presence of chlorine, but this process
completes the conversion in one step
using a single catalyst. The final step is
accomplished via a Diels-Alder cycloaddition
of the dimethylfuran to ethylene,
followed by dehydration to p-xylene. According
to the company, Micromidas is
among the first to investigate the reaction
from dimethylfuran to p-xylene at an
industrial scale.
This process distinguishes itself from
other bio-based chemical pathways in
that it can achieve very high molar yields
with high selectivity - it results in no
other co-products that are common in
conventional p-xylene manufacturing
processes. Traditionally, p-xylene is produced
in petroleum refineries from heavy
naphtha reformate, resulting in a mixture
of p-, m-, and o-xylene, which requires an
additional adsorption separation step
to reach a p-xylene product of desirable
purity. Micromidas hopes its technology
will provide a more direct means to
high-purity p-xylene streams and allow
producers of polyethylene terephthalate
(PET) and polyesters to avoid having to
purchase raw materials from refineries.
Bio-isobutene fermentation process to be piloted
C
onstruction is underway in France on a
pilot plant for what is believed to be the
first fermentation process capable of directly
producing the light olefin isobutene.
Global Bioenergies (Evry, France; www.
global-bioenergies.com) expects to begin
operations of a 500-L fermentation facility
in the second half of 2014 and plans to
follow that with a 5,000-L fermenter in
Germany the following year.
Isobutene is used in chemical applications,
such as in the manufacture of butyl
rubber, as well as for fuel applications,
where it can be dimerized to produce
iso-octane, a high-quality drop-in fuel for
light passenger vehicles.
Global Bioenergies has engineered a
unique metabolic pathway into a strain
of Escherichia coli bacteria, enabling it
to produce isobutene from glucose. To
accomplish the feat, scientists had to
develop a set of three proprietary new
enzymes. The enzymes catalyze a series
of reactions beginning with naturally
occurring upstream products, but that
produce novel intermediate species that
are not metabolized by other cellular enzymes.
The fermentation pathway ends
of purity - up to 99.9% - for
testing and product development
by industrial and research
customers. In parallel
to current production, KIT and
AVA Biochem are optimizing
the production process.
Biogas liquefaction
Last month saw the inauguration
of a biogas liquefaction
plant, which was delivered
by wärtsilä oy (Helsinki, Finland;
www.wartsila.com) to
Cambi AS (oslo, norway), a
specialist in biotreatment. The
plant, operated by Cambi on
behalf of the waste-to-energy
Agency (eGe; oslo) and
the city of oslo, will produce
biomethane from household
food waste to be used as biofuel
in buses in oslo.
The plant, located in nes,
romerike, an agricultural
region close to oslo, will treat
50,000 ton/yr of food waste to
produce around 14,000 nm3/d
of biomethane. The biogas is
then liquified using wärtsilä's
technology, which uses a
mixed refrigerant in combination
with conventional equipment
to make small-scale
LnG plants economical, says
the company. The liquefied
biogas can be efficiently transported
and used as fuel.
in isobutene, which is in a gaseous state
at ambient temperature and pressure.
" One of the problems with many fermentation
processes is that the target
product is often toxic to the production
strain of organisms, " explains Thomas
Buhl, head of business development for
Global Bioenergies. " By engineering a
pathway to produce gaseous isobutene directly,
we can avoid this toxicity because
the product bubbles out of the fermentation
broth and does not accumulate
around the organisms. "
Generating a gaseous product also simplifies
separation and reduces energy
consumption, because no distillation is
required to isolate the product, he adds.
In addition to the ongoing fermentation
scaleup work, Global Bioenergies
continues to optimize its enzymes' activities
and boost expression of the genes for
the enzymes, hoping to commercialize
a process by 2017. The company is also
investigating various feedstocks other
than glucose, Buhl says. After an initial
commercial facility is built, the company
seeks to license its technology to others
for production.
12 CHeMICAL enGIneerInG www.CHe.CoM MArCH 2014
Methane-to-ethylene
Siluria Technologies (San
Francisco, Calif.; www.siluria.
com) and Braskem S.A. (Sao
Paulo, Brazil; www.braskem.
com.br) have recently formed
a broad-ranging collaboration
around the deployment of
Siluria's proprietary oxidative
coupling of methane (oCM)
technology for the direct conversion
of methane in natural
gas to ethylene.
Under the collaboration,
Siluria and Braskem will jointly
explore commercial deployment
of Siluria's technology
for supplying ethylene to
Braskem. In particular, the
two companies will conduct a
joint feasibility study to identify
commercial deployment opportunities
of Siluria's technology
at Braskem's ethyleneconsuming
plants.
Siluria's oCM technology
provides a novel process for
(Continues on p. 14)
http://www.micromidas.com http://www.wartsila.com http://www.siluria http://www.global-bioenergies.com http://www.braskem http://www.com.br http://www.CHe.CoM
Chemical Engineering March 2014

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