Chemical Engineering February 2014 - 12

ChementatoR
(Continued from p. 11)
A sorption-enhanced catalyst improves CO2 methanation
C
onverting CO2 into methane is a way
to mimic the natural carbon cycle and
close the energy cycle by producing synthetic
hydrocarbons (see, for example,
CO2 Utilization, Chem. Eng., July 2013,
pp. 16-19). However, the Sabatier reaction
(CO2 + 4H2 -> 2H2O + CH4) is a
complex surface reaction that is kinetically
limited, says Andreas Borgschulte,
a group leader at the Laboratory for Hydrogen
and Energy of the Swiss Federal
Laboratories for Materials Science and
Technology (EMPA; Dübendorf, Switzerland;
www.empa.ch). Commercial nickelbased
catalysts for this reaction achieve a
90% conversion, but only at temperatures
over 250°C; and at high temperatures,
CO is also formed, he says.
To improve both the yield and selectivity,
Borgschulte's group at EMPA has developed
a new catalyst that simultaneously
absorbs water (diagram), thereby shifting
the reaction to the right according to Le
Chatelier's principle. In laboratory trials,
the so-called sorption catalyst has been
shown to be more active than commercial
catalysts with yields up to 100%.
The new catalyst consists of nanoparticles
of Ni bound to a molecular sieve
(type 5A zeolite with 5-Å sized pores).
To make the catalyst, the zeolite is first
mixed in a solution of NiNO3, whereby
alkali ions are exchanged by Ni+1 ions
within the zeolite. The Ni+1-loaded zeolite
is then dried and calcined with H2
at 650°C, which reduces the Ni+1 to form
nanoparticles of Ni0.
CO2
+ 4H2
CH4
+ 2 H2
O
EMP
So far, the reaction has been carried
out in a single, fixed-bed tubular reactor.
The group plans to make the process
semi-continuous by using several
reactors alternating between reaction
and regeneration (removing absorbed
water). Because the regeneration time
is roughly three times longer than the
reaction time, Borgschulte says at least
four reactors would be used. The group
is also studying the effect of catalyst poisoning
(by sulfur, for example, in biogas
plants), and investigating the possibility
of using other metals besides Ni. The researchers
are in contact with potential
industrial partners.
A new low-temperature shift catalyst
passes longterm testing
A
new water-gas shift catalyst has undergone
1,000 h of successful operation in
a demonstration carried out by the New
Energy and Industrial Technology Development
Organization (NEDO, Kawasaki;
www.nedo.go.jp) and Hitachi, Ltd. (Tokyo,
both Japan; www.hitachi.com). The tests
were performed at the Eagle pilot plant
(Chem. Eng., July 2013, p. 13) using coalderived
syngas, as part of an ongoing
project to develop CCS-IGCC technology
(carbon capture and storage - integrated
coal gasification, combined cycle).
Developed by Hitachi, the new shift catalyst
converts CO2 and water vapor into
CO and H2 with a conversion rate of 40-
70% - even at temperatures below 250°C,
much lower than conventional high-temperature
shift catalysts. The theoretical
conversion rate of 70% was maintained
after 1,000 h of operation, even under conditions
of reduced water content (H2O-toCO2
mole ratio of 1.2 - nearly two thirds
that of normal conditions). The researchers
believe that coal-fired power generation
using the new shift catalyst at a CCSIGCC
facility system has the potential to
reduce CO2 emissions by 200,000 ton/yr
compared to conventional coal-fired power
generation (1,000 MW class).
12 ChemICAL eNGINeerING WWW.Che.Com FebrUAry 2014
mweg thermal power station
in Chemnitz, Germany. This is
the first large-scale application
of the technology in europe.
A set of 60 Lewabrane ro
b400 Fr filter elements apply
a reverse-osmosis (ro) process
to cleanse 50 to 60 m3/h
of pre-treated river water for
steam-generation purposes.
The ro facility in the Chemnitz
power plant was developed
and designed by berkefeld, a
subsidiary of Veolia Water Solutions
& Technologies.
The Chemnitz plant uses
cogeneration to generate
power and district heating.
The power plant draws water
for the cooling processes and
steam production from the rivers
Chemnitz and Zschopau.
The water's intended use
- as cooling water, process
water or almost pure, completely
desalinated water (demineralized
water) for steam
generation - determines the
need for complex mechanical
and chemical treatment procedures.
even after it has been
softened and desalinated
using ion-exchange resins,
the water still contains a considerable
amount of organic
substances that cause excessive
conductivity in the watersteam
cycle that is harmful to
the turbine and other components.
The membrane filter
elements from Lanxess lower
the degree of fluctuation in
water quality and in particular,
filter out organic substances.
Mineral analyzer
researcher Graeme hansford
from the University of Leicester's
Space research Center
(SrC) has recently started
a collaborative project with
bruker elemental Gmbh (Kalkar,
Germany; www.bruker.
com/elemental) to develop a
handheld mineral analyzer for
mining applications - said to
be the first of its kind.
The analyzer will allow
rapid mineral identification
and quantification in the field
through a combination of X-ray
diffraction (XrD) and X-ray
fluorescence (XrF). The novel
XrD method was invented
at the University of Leicester
and has been developed at
the Space research Center.
(Continues on p. 14)
http://www.empa.ch http://www.bruker http://www.nedo.go.jp http://www.hitachi.com http://WWW.Che.Com
Chemical Engineering February 2014

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