The Route to Better Catalysts: From Surface Science to Nanotechnology

Transcription

1 The Route to Better Catalysts: From Surface Science to Nanotechnology by University of California Riverside, CA 92521, USA Phone: 1 (951) Fax: 1 (951) zaera@ucr.edu aldor Topsøe Catalysis Forum Munkerupgaard, Denmark August 27,

2 Introduction Key Issues in Catalysis Selectivity Stability G T, Gases Reactant Product 1 Product 2 A selective process: Consumes less reactants Avoids separation problems Produces less polluting byproducts F. Zaera, J. Phys. Chem. B, 106(16), (2002). F. Zaera, Catal. Lett., 142(5), (2012). Sintering: Reduces surface area modifies surface structure Requires priodic catalyst recycling F. Zaera, Chem. Soc. Rev., 42(7), (2013). F. Zaera, ChemSusChem, 6(10), (2013). 2

3 Introduction Experimental Approach Surface Science with Model Systems Nanotechnology to Prepare Real Catalysts 1 nm Well-defined samples Controlled environments Multiple techniques F. Zaera, Prog. Surf. Sci., 69(1-3), 1-98 (2001). F. Zaera, Int. Rev. Phys. Chem., 21(3), (2002). F. Zaera, J. Phys. Chem. Lett., 1(3), (2010). 3

4 Outline 1. Surface Science of Olefin ydrogenation 2. Shape Selectivity A B 3. Catalyst Nano-Architectures 4

5 Outline 1. Surface Science of Olefin ydrogenation 2. Shape Selectivity 3. Catalyst Nano-Architectures 5

6 Surface Chemistry of Olefin Conversion ydrogenation, Isomerization, and -D Exchange 3 C C C butane C 3 ydrogenation 3 C C C C 3 2-butyl (ads) C=C 1-butene C 2 5 Double Bond Migration 3 C C 3 C=C cis-2-butene Cis-Trans Isomerization 3 C C=C C 3 trans-2-butene oriuti-polanyi mechanism. Does not account for: effect of coadsorbed, carbonaceous layers, stereoselectivity. M. Polanyi, J. oriuti, Trans. Faraday Soc., 30, (1934). F. Zaera, Catal. Lett., 91(1-2), 1-10 (2003). 6

7 Surface Chemistry of Olefin Conversion ydrogenation under UV: TPD Olefin hydrogenation and -D Exchange easily detected by temperature programmed desorption (TPD). Not catalytic. F. Zaera, Langmuir, 12(1), (1996). 7

8 Surface Chemistry of Olefin Conversion ydrogenation under UV: Molecular Beam Ethylene can be hydrogenated with 2 -rich molecular beams, but not catalytically. F. Zaera, T. V. W. Janssens and. Öfner, Surf. Sci., 368(1-3), (1996).. Öfner and F. Zaera, J. Phys. Chem. B, 101(3), (1997). 8

9 Surface Chemistry of Olefin Conversion Model of Working Catalyst Surface Ethylene ydrogenation Ethylidyne -Ethylene Olefin hydrogenation takes place not on clean metals but in the presence of a carbonaceous layer (alkylidynes). F. Zaera, Isr. J. Chem., 38, (1998). F. Zaera, Catal. Lett., 91(1-2), 1-10 (2003). 9

10 Surface Chemistry of Olefin Conversion RAIRS Detection of Alkylidynes In Situ C C s (C 3 ) Ethylidyne (ads) Ethylidyne is present on the surface during ethylene hydrogenation. A. Tillekartne, J. P. Simonovis, M. F. López Fagúndez, M. Ebrahimi, F. Zaera, ACS Catal. 2, (2012). 10

11 Surface Chemistry of Olefin Conversion Kinetics of ydrogenation and -D Exchange Catalysis Fast and extensive ethylene hydrogenation and -D exchange catalysis in the presence of the alkylidyne surface layer. A. Tillekartne, J. P. Simonovis, M. F. López Fagúndez, M. Ebrahimi, F. Zaera, ACS Catal. 2, (2012). 11

12 Surface Chemistry of Olefin Conversion Intermediate ydrogenation Regime Log[P/Torr] Log[Impinging Rate/ML s -1 ] UV Non catalytic Rate ( -C 2 4 ) 1 On clean Pt Pressure Gap (???) Atmospheric P Catalytic Rate P(C 2 4 ) 0 On alkylidyne/pt TOF ~ 1-10??? Log[Reaction Probability] F. Zaera, Phys. Chem. Chem. Phys., 29, (2013). 12

13 Surface Chemistry of Olefin Conversion igh-flux Molecular Beam Kinetics Indeed, reaction probabilities are high (~70%) in the intermediate pressure range. M. Ebrahimi, J. P. Simonovis, F. Zaera, J. Phys. Chem. Lett., 5, (2014). 13

14 Surface Chemistry of Olefin Conversion Carbonaceous Layer at igh TOFs Less surface alkylidyne at the high 2 :C ratios that display high TOFs: Olefin hydrogenation rate may be limited by carbonaceous layer. M. Ebrahimi, J. P. Simonovis, F. Zaera, J. Phys. Chem. Lett., 5, (2014). 14

15 Surface Chemistry of Olefin Conversion ydrogenation Rate vs. Nature of Alkylidyne Olefin hydrogenation rate may depend on the nature of the carbonaceous deposits present on the surface. A. Tillekartne, J. P. Simonovis, F. Zaera (2015). 15

16 Surface Chemistry of Olefin Conversion ydrogenation vs. -D Exchange Switchover in -D exchange TOF End of C 2 4 ydrogenation -D exchange used to evaluate 2 ads as possible rls. Slower under reaction conditions, alkylidyne vs. clean Pt. Switchover in -D exchange TOF at intermediate conversion. J. P. Simonovis, F. Zaera (2015). 16

17 Outline 1. Surface Science of Olefin ydrogenation 2. Shape Selectivity 3. Catalyst Nano-Architectures 17

18 Shape Selectivity Stereoselectivity of Cis-Trans Isomerization 3 C C 3 C=C cis-2-butene Isomerization depends on stereoselectivity of - elimination step from the alkyl intermediate. 3 C C=C C 3 trans-2-butene C 3 C 3 3 C C 3 3 C C 3 C C 3 C C C C 3 3 C C C C 3 cis-2-butene (ads) 2-butyl (ads) trans-2-butene (ads) I. Lee and F. Zaera, J. Am. Chem. Soc., 127, (2005). I. Lee, F. Zaera, Top. Catal., 56(15-17), (2013). F. Zaera, Phys. Chem. Chem. Phys., 15(29), (2013). 18

19 Shape Selectivity Trans-to-Cis Conversion on Pt(111): IR Evidence 998, 1200, 1376, 1460 cm -1 peaks indicate cis-2-butene. Trans-to-cis isomerization. I. Lee and F. Zaera, J. Am. Chem. Soc., 127, (2005). I. Lee, F. Zaera, J. Phys. Chem. C, 111, (2007). 19

20 Shape Selectivity Preparation of Shape-Selected Pt Nanoparticles Pt(111) Tetrahedral Pt Particles (111) facets Pt(111) 1 nm Pt(100) Cubic Pt Particles (100) facets 1 nm T. S. Ahmadi, Z. L. Wang, T. C. Green, A. anglein, M. A. El-Sayed, Science, 272, (1996). I. Lee, R. Morales, M. A. Albiter, and F. Zaera, Proc. Nat. Acad. Sci., 105, (2008). 20

21 Shape Selectivity Supported Shape-Selected Pt Catalysts: Preparation 2 + SiO 2 Rinsing Calcination 2 PtCl 6 PVP Sonication Drying Oxidation/Reduction Pt Colloidal Particle Preparation Dispersion on Silica Xerogel Catalyst Pretreatment I. Lee, R. Morales, M. A. Albiter, and F. Zaera, Proc. Nat. Acad. Sci., 105, (2008). 21

22 Shape Selectivity Preservation of Nanoparticle Shape during Treatment 3 oxidation-reduction cycles at 475 K 10 nm 3 oxidation-reduction cycles at 575 K 10 nm I. Lee, F. Delbecq, R. Morales, M. A. Albiter, and F. Zaera, Nature Mater., 8, (2009). I. Lee, R. Morales, M. A. Albiter, and F. Zaera, Proc. Nat. Acad. Sci., 105, (2008). 22

23 Shape Selectivity Butene Cis-Trans Catalytic Selectivity 3 C C 3 C=C cis-2-butene 3 C C=C C 3 trans-2-butene I. Lee, F. Delbecq, R. Morales, M. A. Albiter, and F. Zaera, Nature Mater., 8, (2009). I. Lee, R. Morales, M. A. Albiter, and F. Zaera, Proc. Nat. Acad. Sci., 105, (2008). 23

24 Shape Selectivity Olefin Cis-Trans Isomerization Relevance Trans fats in partially hydrogenated oils have been linked to a variety of free radical and degenerative conditions such as cancer, arthritis, and cardiovascular disease. 24

25 Shape Selectivity Other Reactions Size and shape sensitivity also seen in: Unsaturated aldehyde (cinammonaldehyde) hydrogenation Glycerol oxidation Y. Zhu, F. Zaera, Catal. Sci. Technol., 4, (2014). Y. Li, F. Zaera, J. Catal., 326, (2015). 25

26 Outline 1. Surface Science of Olefin ydrogenation 2. Shape Selectivity A B 3. Catalyst Nano-Architectures 26

27 Metal Particle Stabilization In-Situ Growth of Support Around Metal Particles Pt TEOS NaO Pt-Deposition Meso-SiO 2 Coating Etching TEOS NaO Q. Zhang, I. Lee, J. Ge, F. Zaera, Y. Yin, Adv. Funct. Mater., 20(14), (2010). I. Lee, J. Ge, Q. Zhang, Y. Yin, F. Zaera, Nano Research, 4(1), (2011). 27

28 Metal Particle Stabilization XPS and CO-IR Titration Characterization 73.8 NaO PtO TEOS CO/Bead CO/SiO Pt surface becomes available again after etching. Q. Zhang, I. Lee, J. Ge, F. Zaera, Y. Yin, Adv. Funct. Mater., 20(14), (2010). I. Lee, J. Ge, Q. Zhang, Y. Yin, F. Zaera, Nano Research, 4(1), (2011). 28

29 Metal Particle Stabilization Stability and Reactivity 60 min NaO TEM after CO ads 40 min NaO No etching Stable toward CO adsorption igher reactivity after etching. Q. Zhang, I. Lee, J. Ge, F. Zaera, Y. Yin, Adv. Funct. Mater., 20(14), (2010). I. Lee, J. Ge, Q. Zhang, Y. Yin, F. Zaera, Nano Research, 4(1), (2011). 29

30 Metal Particle Stabilization Thermal Stability 300 K 875 K 975 K 1075 K Covered Naked Mesoporous layer stops Pt sintering. Q. Zhang, I. Lee, J. Ge, F. Zaera, Y. Yin, Adv. Funct. Mater., 20(14), (2010). I. Lee, J. Ge, Q. Zhang, Y. Yin, F. Zaera, Nano Research, 4(1), (2011). 30

31 Catalyst Nano-Architectures Tandem Catalysis Shaped Nanoparticles Tethering of Molecular Functionality Yolk-Shell Nanostructures Atomic Layer Deposition Catalysts from Dendrimers Self-Assembled Monolayers 31

32 Catalyst Nano-Architectures Tandem Catalysis Shaped Nanoparticles Tethering of Molecular Functionality Yolk-Shell Nanostructures Atomic Layer Deposition Catalysts from Dendrimers Self-Assembled Monolayers 32

33 Catalyst Nano-Architectures 2 Yolk-Shell Synthetic Strategy TiO 2 Au Advantages: Structural stability, prevents sintering. Selective percolation to and from inside. TiO 2 Au I. Lee, M. A. Albiter, Q. Zhang, J. Ge, Y. Yin, F. Zaera, PCCP, 13(7), (2011). I. Lee, J.-B Joo, Y. Yin, F. Zaera, Angew. Chem., Int. Ed., 50(43), (2011). 33

34 Catalyst Nano-Architectures 2 Thermal Stability As Prepared Calcined, 775K 2 50 nm 50 nm Au/TiO 2 -P25 50 nm 50 nm I. Lee, J. B. Joo, Y. Yin and F. Zaera, Angew. Chem., Int. Ed., 43, (2011). 34

35 Catalyst Nano-Architectures 2 Shell Porosity CO- Pt CO- TiO 2 Pt TiO 2 TiO 2 Pt TiO 2 CO, in gas phase or dissolved in a liquid, can reach the metal inside. Also works with larger molecules (Cd, Zn-TPP) and other solvents (EtO) TiO 2 I. Lee, J.-B. Joo, Y. Yin, F. Zaera, Angew. Chem. Int. Ed., 50, (2011). J. Liang, I. Lee, J.-B. Joo, A. Gutierrez, A. Tillekaratne, I. Lee, Y. Yin, F. Zaera, Angew. Chem. Int. Ed., 51, (2012). J. Li, J. Liang, J.-B. Joo, I. Lee, Y. Yin, F. Zaera, J. Phys. Chem. C, 117, (2013). 35

36 Catalyst Nano-Architectures 2 for CO Oxidation CO oxidation at room temperature with 2 comparable to with Au/TiO 2 -P25. I. Lee, J.-B. Joo, Y. Yin, F. Zaera, Angew. Chem., Int. Ed., 50(43), (2011). 36

37 Catalyst Nano-Architectures 2 for CO Oxidation Cryo Oxidation RT Oxidation New cryogenic T CO oxidation channel also with Au@Void@TiO 2. I. Lee, J. B. Joo, Y. Yin and F. Zaera, Angew. Chem., Int. Ed., 43, (2011). I. Lee, J.-B. Joo, Y. Yin, F. Zaera, Surf. Sci., (2015). 37

38 Catalyst Nano-Architectures Tandem Catalysis Way to combine two or more functionalities in one single catalyst: Bring together incompatible functionalities (i.e., acid + base) Can be used to convert short lived intermediates Solve homogeneous catalyst solubility problems 38

39 Catalyst Nano-Architectures Tandem Catalysis Only acid + base produces nitrostyrene (3). 39

40 Conclusions ighly Selective Catalysts Catalyst synthesis with new nanotechnology F. Zaera, J. Phys. Chem. Lett., 1, (2010). I. Lee, M. A. Albiter, Q. Zhang, J. Ge, Y. Yin, F. Zaera, PCCP, 13(7), (2011). F. Zaera, Catal. Lett., 142, (2012). F. Zaera, Chem. Soc. Rev., (2013). F. Zaera, ChemSusChem, 6, (2013). Reaction mechanisms from surface science Catalytic site structure from theory 40

41 Acknowledgements Juan Simonovis Yujung Dong Ilkeun Lee A Alejandro Negrete Zhihuan Weng B Prof. Yadong Yin 41