Chemical Engineering October 2016 - 8

by Japan's Ministry of the
Environment. Installed in the
Shoro Dam in Shiranuka-cho,
Shiranuka-gun, Hokkaido, the
system produces approximately
35 Nm3/h of hydrogen
for a small community.
CO2 TO CO
The research group of professor
Yoshinori Naruta at Chubu
University (Kasugai City,
www3.chubu.ac.jp) has developed
an iron-based photoelectrocatalyst
that efficiently and
selectively converts CO2 into
CO. The bio-inspired catalyst
- a binuclear Ni/Fe carbonmonoxide
dehydrogenase
(CODH) - has shown a 93%
selectivity for CO in the reduction
of CO2 at the anode of an
electrochemical cell operating
with artificial sunlight for 6 h.
The researchers used several
co-facial porphyrin dimers
with different substituents
as suitable ligands for holding
two Fe ions with suitable
Fe-Fe separation to efficiently
and selectively promote CO2
to CO conversion with high
turnover frequencies.
WASTE-FREE WAFERS
Silicon wafers are essential
building blocks for the solarenergy
industry, but their
manufacture often results in a
great deal of wasted materials,
from scrap silicon to singleuse
cutting and sawing tools.
A new production technique,
dubbed Direct Wafer from
1366 Technologies Inc. (Bedford,
Mass.; www.1366tech.
com), enables Si wafer manufacture
without the waste that
(Continues on p. 10)
This new, dual-pressure HNO3 process is
commercially available
L
ast month, Weatherly
Inc., a wholly
owned subsidiary
of KBR Inc.
(Houston; www.kbr.com)
introduced its new dualpressure
nitric acid (DPNA)
technology, which enables
economically
viable
production
of HNO3 in large
scale [over 1,000 metric
tons per day (m.t./d)], as
part of large fertilizer-production
complexes. The
technology was launched
at the 2016 AN-NA (Ammonium
Nitrate - Nitric
Acid) conference (September
16-23; Eindhoven, the
Netherlands).
Platinum recovery
Air
Air compression
Mixing and
oxidation reaction
Process heat
recovery
LP weak acid
condensing
NOx gas
compression
HP weak acid
condensing
N20 abatement
Power recovery
NOx abatement
Ammonia
vaporization
Liquid ammonia
Tail gas
exhaust
In the DPNA process
(diagram), ammonia is
first oxidized with air over
a platinum catalyst at
high temperature and low
pressure (LP). The product
of the LP oxidation is
passed through a heat exchanger to recover
a major portion of the heat. The process gas
is cooled and oxidized further in a LP cooler
condenser, where NO, NO2, O2 and water
combine to form dilute HNO3. Some of the
reaction energy is recovered and used to reheat
the tail gas. The LP process gas is then
compressed in the NOx-gas compressor,
and fed to high-pressure (HP) cooler condenser
and absorber to form product HNO3
(68%). Tail gas from the absorber is reheated
to 1,150°C and used to drive a hot-gas expander
to generate power for the air compressor
and NOx-gas compressors.
Weatherly's DPNA process is said to deliver
lower operating costs with its more efficient
R
8
esearchers at the Agency for
Science, Technology and Research
(A*STAR; Singapore;
www.a-star.edu.sg), led by
Sudhakar Jonnalagadda, have provided
another step toward replacing petrochemicals
with renewable resources in
the manufacture of synthetic fibers and
plastics. The team has genetically modified
Escherichia coli bacteria to produce
muconic acid from glucose. Muconic
acid is a commercially important raw
material used in pharmaceuticals, functional
resins and agrochemicals, and is
Absorption
Water
Nitric acid
heat-recovery design. Tail gas exits the system
at 620°C, compared to the lower (490°C)
temperature of alternative DPNA processes.
This enables more efficient recovery of heat
that is subsequently used to generate energy
to power up the system. As a result, the new
process offers an operating cost advantage
over competing technologies of $4-5/ton of
nitric acid produced, says KBR.
The DPNA process also utilizes Weatherly's
vertical reactor - a compact, proven
design widely used in mono-pressure HNO3
plants - that requires less steel and piping
than traditional plants. That means capital
costs for Weatherly plants are 5-10% less
than competing designs, says KBR.
Engineering bacteria to make muconic acid
also a precursor of adipic acid, used to
manufacture nylon.
Jonnalagadda says bacteria do not
naturally produce the required substances
in significant quantities, so the
trick is to persuade these bacteria to
become mini manufacturing plants for
chemicals required by industry. The
A*STAR team inserted three genes
into E. coli to establish the metabolic
pathway that produces muconic acid.
The challenge was to cause the
bacteria to divert more glucose toward
the desired products, Jonnalagadda
says. The team had to control
the combined activity of foreign and
native genes to prevent the accumulation
of metabolic intermediaries as well
as optimize the efficiency of muconic
acid production. Computer simulation
was used to study the metabolism of
the genetically engineered bacteria,
and for deciding on the required genetic
changes.
The team is now looking at other
ways to improve the efficiency of muconic
acid production. " We are at an
early stage, " says Jonnalagadda.
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
OCTOBER 2016
http://www.kbr.com http://www3.chubu.ac.jp http://www.1366tech http://www.a-star.edu.sg http://WWW.CHEMENGONLINE.COM
Chemical Engineering October 2016

Table of Contents for the Digital Edition of Chemical Engineering October 2016
