The catalytic reduction of C02

1. Chemical Reaction Engineering Group (CREG)
N01-Faculty of Chemical Engineering
Universiti Teknologi Malaysia
UTM 81310 Johor Bahru, Johor Malaysia.
noraishah@cheme.utm.my
www.cheme.utm.my
Carbon Dioxide Reduction with Hydrogen
Using Photonanocatalyst
Nor Aishah Saidina Amin

2. Presentation Outline
• Background of Study
• Research Scope
• Methodology
• Results and Discussions
• Conclusions
• Acknowledgement

3. Global anthropogenic greenhouse gas emissions broken down into 8 different sectors.
[http://en.wikipedia.org/wiki/Greenhouse_gas]
Majour
contributors
Background

4. • Energy consumption has been
increasing with world
population
• Fossil fuels are the main source
of energy supply
• Reserves of fossil fuel is fossil
depleting Combustion of fossil
fuels generates greenhouse
CO2
Background
Fossil fuel
Combustion
Greenhouse
Gas CO2
Energy
Crisis and
Global
Warming

5. How?
(i) How CO2 can be re-utilized easily and efficiently
(ii)How CO2 can be recycled or converted to fuels
Mitigation of
Greenhouse Gas CO2

6. 6
Conversion of
Carbon Dioxide
Biological
(EtOH, sugar,
CH3COOH)
Electrochemical
(EtOH, HCOOH,
CO)
Photocatalysis
(CO, CH4, HC,
MeOH, HCOOH)
Thermal
reforming
Plasma
reforming
Reforming
(CO, H2)
Recycling of CO2 to Fuels
• Required higher
temperature and
pressure
• Thus, instability of
catalysts and
uneconomical
• Required
electricity for
the process
• Required high
voltage and
cause fouling on
electrode
surface
• Required
biocatalyst
• Required very
specific
conditions
• Specific
bioreactors
• Short life time
of biocatalyst
• Workable under
solar energy
• Economical
process
• Required normal
temp and
pressure
• Sustainable
process
• High stability of
catalysts 6

7. Semiconductor
Material
Photocatalytic
Reactor
Reducing
Agent
Photocatalysis
System
Efficient
Phototechnology
for CO2 Reduction
• Higher photonic Efficiency,
• higher illumination area
• Have good photoactivity
• Higher charger production
• Lower charges recombination
• Can easily be oxidized
• Can reduced CO2
• Can help to produce
• desire products

8. Hydrogen
Reductant
Plasmonic
PhotoCatalysts
Monolith
Photoreactor
What we are Offering??

9. 9
Hydrogen Reducing Agent
,
2 2 2
CO H CO + H O
hv catalyst
 
 (RWGS reaction)
,
2 2 2 4 2
2CO +6H C H +4H O
hv catalyst


,
2 2 2 6 2
2CO +7H C H +4H O
hv caalyst


,
2 2 3 6 2
3CO +9H C H +6H O
hv catalyst


,
2 2 3 8 2
3CO +10H C H + 6H O
hv catalyst


Single step
F-T process
• Hydrogen is good
reducing agent for CO2
conversion via RWGS
reaction
• Syngas (CO and H2) can
be used for F-T process
• CO2 reduction with H2
can also be produced
hydrocarbons in single
step.
• H2 for CO2 reduction
can be obtained from
water splitting

10. Monolith Photoreactor
√ It has microchannels of
different shape and sizes
√ Light distribution is
effective over the catalyst
surface.
√ Larger surface area to
reactor volume.
√ Catalyst loading is higher
with enhanced stability.
√ Very suitable for systems
operating in gas- solids.
√ Larger conversion with
improved selectivity.
√ Higher quantum
efficiency
√ Higher light distribution
over the catalyst
Monolith
10
 Honeycomb, foam or fibers structure
 Channels have square, circular, and triangular
 Density varies from 9 to 600 cells per square inch
(CPSI)
 Higher void fraction (65 to 91 %) compared to
packed bed catalyst (36 to 45 %)

11. 11
LSPR of Au
(a)
(b)
Plasmonic Au/TiO2 Photonanocatalyst
TiO2
When the incident light is (in the
range of LSPR) absorbed by Au-
metal NPs, electric filed (e-/h+ ) is
produced (Fig. a)
Plasmonic electrons are transferred
to TiO2 CB band for its activation
(Fig. B)
 Efficient separation of electrons
 Efficient CO2 reduction via SPR
effect
 Higher efficiency for trapping
electrons
 Au can enhance efficiency under
UV and visible light

12. Schematic of Monolith Reactor
Experimental Rig
Experimental Setup
Monoliths

13. Catalyst Preparation and Coating
Hydrolysis
Au-loading
Dip-coating
Drying and
Calcination
Ti (C3H7O)4
+ isopropanol
Acetic acid
+ isopropanol
Gold chloride
+ isopropanol
Aging
Monolith
Calcined at 500oC
for 5h @ 5oC/min
Dried at 80 oC
for 24 h

14. SEM and TEM Analysis
• Uniform coating of catalysts over the
monolith surface
• TiO2 particles are spherical in shape
and uniform size
• Au/TiO2 have mesoporous structure
 TEM images of Au/TiO2 exhibit
uniform particle size and mesoporous
structure of TiO2
 TiO2 d-spacing confirmed anatase
TiO2.
TEM (Au/TiO2)
SEM
TiO2 Au/TiO2
Front view Side View

15. 10 20 30 40 50 60 70 80
Intensity
(a.u)
2-Theta (degree)
TiO2
0.2% Au-TiO2
0.3% Au-TiO2
0.5% Au-TiO2
0.0 0.2 0.4 0.6 0.8 1.0
0
20
40
60
80
100
120
140
160
Relative pressure (P/Po)
Volume
adsorbed
(cm
3
/g
at
STP)
TiO2
0.3 wt.% Au/TiO2
0.5 wt.% Au/TiO2
200 300 400 500 600 700 800
Absorbance
(a.u)
Wavelength (nm)
TiO2
0.3% Au/TiO2
0.5% Au/TiO2
(a) (b)
(c)
XRD
UV-Vis
BET
XRD, BET and UV-Vis Analysis
Plasmon effect
(a) Anatase phase in TiO2 and Au/TiO2
samples
(b) N2 adsorption-desoprtion plots show
isothersms of type IV, confirming
mesoporous materials of TiO2 and
Au/TiO2
(c) UV-Visible analysis confirmed
Plasmonic effect in Au/TiO2 catalyst
A
A A
A
A=anatase

16. Summary
of Analysis
Element B.E (eV) State
Ti2p 459.50
465.20
Ti4+
Au4f 83.86
88.12
Au
O1s 530.72
532.94
O-O
O-H
C1s 284.60
286.05
C-C
C-O
Catalysts
BET
surface area
(m2/g)
BJH
adsorption
surface area
(m2/g)
BJH
pore volume
(cm3/g)
Crystallite
size
(nm)
Band gap
energy
(eV)
TiO2 43 52 0.134 19 3.12
0.3 wt.% Au-
TiO2
46 58 0.23 17 3.03
0.5 wt.% Au-
TiO2
47 74 0.24 18 2.93
 Au has no effect on BET
surface area
 Au has no effect on
Crystallite size
 Band gap energy shifted to
visible region in Au/TiO2
 Gold was present over TiO2
in metal state
Table 1
Table 2
Nanocatalyst

17. • Plasmonic Au/TiO2 registered significantly
enhanced CO production activity over irradiation
time
• Optimum Au-loading of 0.5%Au was
determined
• Maximum yield of CO was 12445 µmole g-
catal.-1
• Steady sate process achieved after 2h of
0 2 4 6 8 10
0
2000
4000
6000
8000
10000
12000
14000
16000
Yield
of
CO
(µmole
g-catal.
-1
)
Irradiation time(h)
TiO2
0.2% Au-TiO2
0.3% Au-TiO2
0.5% Au-TiO2
0.7% Au-TiO2
0 2 4 6 8 10
0
2
4
6
8
10
12
14
16
18
20
22
24
Yied
of
CH
4
(µmole
g-catal.
-1
)
Irradiation time (h)
TiO2
0.2% Au-TiO2
0.3% Au-TiO2
0.5% Au-TiO2
0.7% Au-TiO2
CO production
CH4 production
(a) Maximum production of CH4 initially
(b) CH4 production decreased due to photo-
oxidation back into CO2 by O2 produced over
catalyst surface
(c) Saturation of catalyst sites with intermediate
species or deactivation of catalyst
(d) photo-reduction of products back to CO2.
(a)
(a)
Photoactivity Test of Continuous
CO2 Reduction to CO
Fig. Effects of Au-loading and irradiation time on CO2 reduction with H2 at CO2/H2 ratio 1.0, molar flow rate
20 mL/min, and temperature 100oC; (a) CO production, (b) CH4 production.

18. Summary of Results
C2H4 C2H6 CH4 CO
0
20
40
60
80
100
Selectivity
(%)
Products
TiO2
0.5 wt.% Au/TiO2
(b)
TiO2 0.2% Au-TiO2 0.3% Au-TiO2 0.5% Au-TiO2 0.7% Au-TiO2
0
500
1000
1500
2000
2500
3000
3500
4000
4500
Yield
rate
(µmole
g-catal
-1
h
-1
)
Photocatalysts
CH4
CO
(a)
Fig. (a ) Yield rates of products over Au/TiO2
catalysts
Fig. (b) Selectivity of products over
Au/TiO2 catalysts.
318
fold
0.5% Au/TiO2
TiO2
CO selectivity
92% to 99%

19. Catalyst Stability Test
a= CO production
(a) In the cyclic runs over prolonged irradiation time, higher stability of
catalysts
(b) In second and third cycles, photoactivity slightly reduced
(c) Decreased in photoactivity of Au/TiO2 catalyst was possibly due to active
sites blockage with intermediate species.
0 2 4 6 8 10
0
2000
4000
6000
8000
10000
12000
14000
Yield
of
CO
(ppm)
Irradiation time (h)
Cycle R-1
Cycle R-2
Cycle R-3
0 2 4 6 8 10
0
1
2
3
4
5
6
7
8
0 2 4 6 8 10
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Yield
of
CH
4
(ppm)
Irradiation time (h)
Cycle R-1
Cycle R-2
Cycle R-3
Yield
of
C
2
H
6
(ppm)
Irradiation time (h)
Cycle R-1
Cycle R-2
Cycle R-3
b= hydrocarbons production
CH4 C2H6

20. Conclusions
 Enhanced efficiency of monolith photoreactor for CO2
reduction to fuels
 Efficient CO2 reduction with H2 to CO and HCs over
Au/TiO2.
 Yield of CO production over Au/TiO2 increased to 318
times higher than TiO2
 Selectivity of CO production reached above 99% by Au
 Enhanced Au/TiO2 activity was due to plasmonic effect
 Efficient trapping of electrons and inhibited charges
recombination by Au-metal
 Tests revealed prolonged stability of Au/TiO2 in cyclic
runs.

21. Acknowledgements
Ministry of Higher Education (MOHE) Malaysia for financial
support under NanoMite LRGS (Long-term Research Grant
Scheme , Vot 4L839),
Universiti Teknologi Malaysia (UTM) for the RUG (Research
University Grant, Vot 02G14) and
FRGS (Fundamental Research Grant Scheme, Vot 4F404).

22. THANK YOU FOR YOUR ATTENTION
Chemical Reaction Engineering Group (CREG)
N01-Faculty of Chemical Engineering
Universiti Teknologi Malaysia
UTM 81310 Johor Bahru, Johor Malaysia.
noraishah@cheme.utm.my
www.cheme.utm.my/staff/noraishah