Chemical Engineering August 2014 - 16

A two-step process for making graphene
ChementatoR
A
Korean team has developed a carbon
material that is as effective
as graphene in applications, such as
solar cells and semiconductor chips,
using a process that requires only two
steps instead of the usual eight.
High-quality graphene is usually
manufactured using chemical vapor
deposition (CVD). In this method the
graphene is manufactured on the
board of a metal film that serves as
a catalyst. The graphene is made by
catalytic conveRteRs
(Continued from p. 15)
polyol reducing agent, such as ethylene
glycol. Nanoparticles of the metal
become deposited on the surface of the
dried alumina powder by the polyol
reduction reaction in heated nitrogen
gas. Finally, the residual polyol is
burned off, leaving behind a catalyst
system with supported nanoparticles.
Not only does the new catalyst system
require less Pt, but it is said to be
blowing out a gas called the source
gas onto the board. The metal must
be subsequently removed and the
graphene has to be transported to another
board. This method is therefore
labor intensive, and there is usually a
degradation of the quality of the graphene,
with the appearance of wrinkles
and cracks.
The Korean team, led by Han-Ik Joh
of the Korea Institute of Science and
Technology (KIST, Seoul; http://eng.
more resistant to high temperatures.
Compared to existing Pt-Pd catalyst
systems, the new system exhibits the
same, or better performance for the
treatment of hydrocarbons from exhaust,
achieving a 95% cleaning efficiency
at temperatures above 250°C.
The high performance is believed to
be due to the small size of the nanoparticles
(about 3-nm dia.), which are
insulated from the detrimental effects
of sintering.
kist.re.kr), Seok-In Na of Chonbuk
National University (Jeonju; www.
chonbuk.ac.kr), and Byoung Gak Kim
of the Korean Research Institute of
Chemical Technology (KRICT, Daejeon;
www.krict.re.kr) has developed
a carbon nanosheet in a two-step
process consisting of coating the substrate
with a polymer solution and
heating it. The team synthesized a
polymer with a rigid ladder structure
- PIM-1 (polymer of intrinsic microporosity-1)
to form the carbon nanosheet.
The carbon nanosheet is spincoated
on the substrate using PIM-1
solution with a light green color, and
then heat-treated at 1,200°C, leading
to a transparent and conducting carbon
nanosheet.
The new method allows massproduction
of the carbon nanosheets
with a high quality, since it bypasses
the steps that tend to form defects,
such as the elimination of the metal
substrate and the transfer of the graphene
to another board.
■
Simultaneous heat transfer
and mass transfer model
in column.
Good thinking.
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A
Engineering advanced
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Chemical Engineering August 2014

Table of Contents for the Digital Edition of Chemical Engineering August 2014
