| |
|
|
|
|
 |
Associate Professor CHUAH GAIK-KHUAN
B.Sc.(Hons), 1982, National University of Singapore; Ph.D., 1987, Texas A&M University
Contact Information
|
|
Department of Chemistry, NUS
3 Science Drive 3
Singapore 117543
|
Office: S5-04-03
Tel: (65)-6516-2839
Fax: (65)-6779-1691
Email: chmcgk@nus.edu.sg |
|
Research Interests
Heterogeneous Catalysis, Nanocrystalline Materials, Green Chemistry
and Solid Acids, High Porosity Materials
Our research interests are focused on materials for heterogeneous
catalysts. Catalysis plays an important part in our lives as many
of the products and energy-related activities are derived from its
application. Most of the chemical reactions in industry and biology
are catalytic. Catalysis is the key to the efficiency of chemical
reactions and is involved in the processing of a large fraction
of products. In the last decade, catalysis has played a crucial
role in the protection of our environment. Catalysts are used to
reduce and minimize pollutants emitted during the processing of
fuels and chemicals. They are vital to the production of new, environmentally
friendlier fuels and chemicals. In addition, an important role of
catalysts is to reduce undesirable emissions from automobiles and
power plants.
High Porosity Materials
One of our research interests is in improving the properties of
existing materials. Both crystalline and amorphous materials are
investigated. By studying the chemistry involved in the processing,
we try to tailor materials with the suitable properties. For example,
in order to be useful as catalyst supports, a material must have
a high surface area. We are able to make high surface area support
materials like zirconia, alumina and titania which have the additional
advantages of being thermally stable and crystallizing in only one
phase. The research focuses on the parameters influencing the properties
of these materials such as pore size and surface area.
Crystal structure of zirconia
Application of Zeolites in Organic Reactions and Fine Chemical
Synthesis
The use of zeolites in the synthesis of organic intermediates and
fine chemicals is in a relatively early stage of development. This
is largely due to the limited size of the zeolite pore systems which
blocks out bulky organic molecules. Organic catalysis involves the
application of zeolites and related catalysts in organic synthesis
with the view to produce new low-waste processes. The Meerwein-Ponndorf-Verley
reduction of aldehydes and ketones to the corresponding alcohols
has traditionally been carried out using homogeneous catalysts like
aluminium or titanium alkoxides. The reaction proceeds with high
chemoselectivity for unsaturated aldehydes and ketones in contrast
to hydrogenation using noble metals. Because of the mild reaction
conditions, the reaction is widely used in the synthesis of natural
products, pharmaceuticals, flavour and fragrance agents. The use
of heterogeneous catalysts for the MPV reaction, offering ease of
use, handling, separation and recycling, in contrast to homogeneous
catalysts. We have recently synthesized Zr-zeolite beta and found
it to be a highly active and selective catalysts for the MPV reduction
of a number of aldehydes and ketones, with the added advantage that
these materials were highly water-resistant, hence allowing for
ease of handling. We are exploring the activity of zeolite beta
in a number of organic reactions.
Micro-Mesoporous Materials
The synthesis of porous inorganic materials possessing multiple
pore dimensions in a single material is a major contemporary technical
challenge with clear applications in catalysis and separation technologies.
The formation of such materials with stable crystalline structures
has proven to be an even more challenging target. The formation
of mesoporous or mesostructured zeolites has been a long sought
after goal. The synthesis methods generally succeeded in producing
either intimate mixtures of two different materials, or simple degradation
of one or other of the components. Among the recurring themes in
the synthesis of both mesostructures and zeolites is the power of
the synthetic method where subtle changes can have profound effects
on the outcome. We investigate how the modification of the zeolite-seed
assembly method permits control over the formation of mesostructured
and hexagonally ordered crystalline zeolite.
 |
 |
| Crystal structure of zeolite beta |
TEM of micro-mesoporous BEA* |
Green Chemistry
Traditionally, oxidation can be carried out using heavy metal oxidants
which forms toxic wastes. Nitric acid, a conventional industrial
oxidant, leads to the formation of various nitrogen oxides. We explore
the use of oxygen, air and hydrogen peroxide for the synthesis of
fine chemicals and pharmaceuticals, many of which require high chemical
purity. Furthermore, these oxidants do not form waste-polluting
wastes. Our research here focuses on catalysts and catalytic systems
using these green oxidants.
Representative Publications
 Yongzhong
Zhu, S. Jaenicke, and G. K. Chuah
Supported zirconium propoxide - a versatile heterogeneous catalyst
for the Meerwein-Ponndorf-Verley reduction
Journal of Catalysis, 218, 2003, 396 - 404.
Stephen
A. Bagshaw, Stephan Jaenicke and Chuah Gaik Khuan
Structure and Properties of Al-MSU-S Mesoporous Catalysts: Structure
Modification with Increasing Al Content
Industrial Engineering and Chemical Research,42, 2003, 3989-4000.
D.
B. Ravindra, Y. T. Nie, S. Jaenicke and G. K. Chuah
Isomerisation of -Pinene Oxide over Microporous and Mesoporous Catalysts,
Catalysis Today, 96 (2004) 147 - 153.
Yongzhong
Zhu, Gaikhuan Chuah, Stephan Jaenicke
Chemo- and Regioselective Meerwein-Ponndorf-Verley and Oppenauer
Reactions,
Journal of Catalysis, 227 (2004) 1- 10.
Shu
Hua Liu, Gaik Khuan Chuah, Stephan Jaenicke
Liquid-phase Oppenauer oxidation of primary allylic and benzylic
alcohols to corresponding aldehydes by solid zirconia catalysts,
Journal of Molecular Catalysis A, 220 (2004) 267 - 274.
Zhu
Yongzhong, Nie Yuntong, Stephan Jaenicke, Gaik-Khuan Chuah
Cyclisation of citronellal over zirconium zeolite beta-a highly
diastereoselective catalyst to (±)-isopulegol, Journal of
Catalysis, 229 (2005), 404 - 413
|
|
