1. Xiaopeng Min, Yin Wang (Advisor)
Catalytic Destruction of Organic Contaminants by Structured Palladium-based Materials
Xiaopeng Min, Yin Wang (Advisor)
Department of Civil and Environmental Engineering
University of Wisconsin-Milwaukee

2. Outline Background Catalyst Design and Characterization
Catalyst Performance
Conclusion

3. Outline Background Catalyst Design and Characterization
Catalyst Performance
Conclusion

4. Background
H H
H H
-Cl -H Pd
-NO2
-NH2
Chaplin et al Environ. Sci. Technol.
Organic micropollutants are increasingly detected in various water sources, and their presence may pose adverse effects.
Pd-based hydrogenation catalysis has emerged as a promising water purification strategy for reductively destruction of waterborne contaminants. 1

5. Background Challenge: low activity and difficulty for recovery
Wang et al ACS Catalysis.
Yi et al Chemistry of Materials.
Challenge: low activity and difficulty for recovery
Magnetic core: catalyst recovery
Mesoporous silica shell: the dispersion of reactive Pd sites 2

6. Research Objectives -Cl -NO2
Design advanced structured materials to immobilize Pd nanoparticles to enhance the activity and recovery
Evaluate the performance of the integrated catalyst in reduction of organic contaminants
-Cl -H
-NO2
Pd (II) Salt:
Na2PdCl4
Pd(OAc)2
-NH2 3

7. Outline Background Catalyst Design and Characterization
Catalyst Performance
Conclusion

8. Catalyst Design
TEOS
CTAB 4

9. Catalyst Design
APTES
MPTES 5

10. Catalyst Characterization
-NH2
-Na2PdCl4
Pd: 4.42%
-SH
-Na2PdCl4
Pd: 2.65%
-NH2
-Pd(OAc)2
Pd: 2.22%
-SH
-Pd(OAc)2
Pd: 3.96% 6

11. Catalyst Characterization
SEM-EDS & TEM-EDX
Pd Size < 5 nm 7

12. Outline Background Catalyst Design and Characterization
Catalyst Performance
Conclusion

13. Experimental Set-up
(4.42 wt% Pd), Commercial (4.28 wt% Pd)
Catalyst loading: mgPd·L-1
Contaminants Conc.: mg·L-1
pH: 7
Phosphate buffer: 1 mM
Room temperature. PH2 = 1 atm
Contaminants
Products Pd
catalyst
H2, water
Catalyst and Contaminants
Off Gas
UV and HPLC Analysis
Sampling
PH2 = 1 atm 9

14. Nitroaromatic
50 mg·L-1 Nitroaromatic
Catalyst 0.25 mgPd·L-1
1 atm H2
pH 7 NP NB NT NA
Nitrobenzene > Nitrobenzoic Acid > Nitrotoluene > Nitrophenol 12

15. Selectivity Selectivity: > 95 % 50 mg·L-1 Nitroaromatic
Catalyst 0.25 mgPd·L-1
1 atm H2
pH 7
Selectivity: > 95 % 13

16. Reusability After 5 runs, reduction of nitrobenzene: > 98 %
50 mg·L-1 Nitrobenzene
Catalyst 0.25 mgPd·L-1
1 atm H2
pH 7
Reaction time: 30 min
After 5 runs, reduction of nitrobenzene: > 98 % 14

17. Outline Background Catalyst Design and Characterization
Catalyst Performance
Conclusion

18. Conclusion
Load Pd nanoparticles in mesoporous SiO2 using –NH2 as modification functional group and Na2PdCl4 as Pd source.
Immobilization of Pd nanoparticles in mesoporous SiO2 enhance the reduction of organic contaminants.
Commercial
k [L / (h · gPd)]
k [L / (h · gPd)]
Nitrobenzene
44400
2880
-NH2
-Na2PdCl4
Water
Room Temperature
H2 atmosphere
Nitrophenol
12720
480
Nitrotoluene
19440
3120
Nitrobenzoic Acid
38160
720 15

19. Thank you ! Acknowledgment
This work was financially supported by the fund from College of Engineering and Applied Science, University of Wisconsin-Milwaukee.
Thank you !