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

Outline Background Catalyst Design and Characterization Catalyst Performance Conclusion

Outline Background Catalyst Design and Characterization Catalyst Performance Conclusion

Background H H H H -Cl -H Pd -NO2 -NH2 Chaplin et al. 2012. 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

Background Challenge: low activity and difficulty for recovery Wang et al. 2014. ACS Catalysis. Yi et al. 2006. Chemistry of Materials. Challenge: low activity and difficulty for recovery Magnetic core: catalyst recovery Mesoporous silica shell: the dispersion of reactive Pd sites 2

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

Outline Background Catalyst Design and Characterization Catalyst Performance Conclusion

Catalyst Design TEOS CTAB 4

Catalyst Design APTES MPTES 5

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

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

Outline Background Catalyst Design and Characterization Catalyst Performance Conclusion

Experimental Set-up Fe3O4@mSiO2-Pd (4.42 wt% Pd), Commercial SiO2@Pd (4.28 wt% Pd) Catalyst loading: 0.25 - 0.5 mgPd·L-1 Contaminants Conc.: 20 - 50 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

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

Selectivity Selectivity: > 95 % 50 mg·L-1 Nitroaromatic Catalyst Fe3O4@mSiO2-Pd 0.25 mgPd·L-1 1 atm H2 pH 7 Selectivity: > 95 % 13

Reusability After 5 runs, reduction of nitrobenzene: > 98 % 50 mg·L-1 Nitrobenzene Catalyst Fe3O4@mSiO2-Pd 0.25 mgPd·L-1 1 atm H2 pH 7 Reaction time: 30 min After 5 runs, reduction of nitrobenzene: > 98 % 14

Outline Background Catalyst Design and Characterization Catalyst Performance Conclusion

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 SiO2@Pd k [L / (h · gPd)] Fe3O4@mSiO2-Pd k [L / (h · gPd)] Nitrobenzene 44400 2880 Fe3O4@mSiO2-Pd -NH2 -Na2PdCl4 Water Room Temperature H2 atmosphere Nitrophenol 12720 480 Nitrotoluene 19440 3120 Nitrobenzoic Acid 38160 720 15

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