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

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

3. Background Majour contributors
Global anthropogenic greenhouse gas emissions broken down into 8 different sectors. [

4. Fossil fuel Combustion Energy Crisis and Global Warming
Background
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
Fossil fuel Combustion
Greenhouse Gas CO2
Energy Crisis and Global Warming

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

6. Recycling of CO2 to Fuels
Conversion of Carbon Dioxide
Reforming
(CO, H2)
Electrochemical
(EtOH, HCOOH, CO)
Biological
(EtOH, sugar, CH3COOH)
Photocatalysis
(CO, CH4, HC, MeOH, HCOOH)
Plasma reforming
Thermal reforming
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
Required higher temperature and pressure
Thus, instability of catalysts and uneconomical 6

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

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

9. Hydrogen Reducing Agent
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
(RWGS reaction)
Single step
F-T process

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
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. Plasmonic Au/TiO2 Photonanocatalyst
LSPR of Au
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)
(a)
Efficient separation of electrons
Efficient CO2 reduction via SPR effect
Higher efficiency for trapping electrons
Au can enhance efficiency under UV and visible light
(b)
TiO2

12. Experimental Setup Monoliths Experimental Rig
Schematic of Monolith Reactor
Experimental Rig

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

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

15. XRD, BET and UV-Vis Analysis
A=anatase
BET A A A
(c)
Anatase phase in TiO2 and Au/TiO2 samples
N2 adsorption-desoprtion plots show isothersms of type IV, confirming mesoporous materials of TiO2 and Au/TiO2
UV-Visible analysis confirmed Plasmonic effect in Au/TiO2 catalyst
Plasmon effect
UV-Vis

16. BJH adsorption surface area
Summary of Analysis
Nanocatalyst
Table 1
Catalysts
BET
surface area
(m2/g)
BJH adsorption surface area
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
Table 2
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
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

17. Photoactivity Test of Continuous
CO2 Reduction to CO
(a)
CH4 production
(a)
CO production
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.
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 µmole g-catal.-1
Steady sate process achieved after 2h of irradiation time.
Maximum production of CH4 initially
CH4 production decreased due to photo-oxidation back into CO2 by O2 produced over catalyst surface
Saturation of catalyst sites with intermediate species or deactivation of catalyst
photo-reduction of products back to CO2.

18. Summary of Results CO selectivity 92% to 99% 318 fold
0.5% Au/TiO2
CO selectivity
92% to 99%
318
fold
TiO2
Fig. (a ) Yield rates of products over Au/TiO2 catalysts
Fig. (b) Selectivity of products over Au/TiO2 catalysts.

19. Catalyst Stability Test
b= hydrocarbons production
a= CO production
CH4
C2H6
In the cyclic runs over prolonged irradiation time, higher stability of catalysts
In second and third cycles, photoactivity slightly reduced
Decreased in photoactivity of Au/TiO2 catalyst was possibly due to active sites blockage with intermediate species.

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 Johor Bahru, Johor Malaysia.