Gas-phase deposition (ALD) for highly efficient preparation of catalysts

Transcription

1 Gas-phase deposition (ALD) for highly efficient preparation of catalysts J. Ruud van Ommen Product & Process Engineering ( ChemE Delft University of Technology, the Netherlands Delft University of Technology Challenge the futurechallenge the future

2 Introduction: ALD on fluidized powders Efficiency of precursor usage Batch and continuous reactor technology Application examples

3 Atomic Layer Deposition (ALD) on Powders ALD: a gas-phase deposition technique with sub-nm control A B A B A B A B A B etc. Number of cycles determines layer thickness

4 Chemistry of ALD Al 2 O 3 Pt Polyester (molecular layer Deposition, MLD)

5 Film growth / island growth on (nano)particles Al 2 O 3 film ~ 3 nm Pt clusters ~ 2 nm 10 nm

6 Wide range of coatings possible Periodic table of ALD Miikkulainen et al., J. Appl. Phys. 113 (2013) Status Dec the pure element has been grown the pure element has been grown compounds with O compounds with F 1 compounds with O compounds with F H compounds with N Z Z other compounds other compounds He 3 4 compounds with compounds with Te compounds with S compounds with Te Li Be B C N O F Ne compounds with Se compounds with Se Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac** Rf Db Sg Bh Hs Mt Ds Rg Cn Mostly applied to flat substrates (semiconductor industry)

7 Fluidization of nanoparticles 4 mm N 2 A B A B A B van Ommen et al., J Nanoparticle Res 14 (2012) 737 De Martín et al., J Nanoparticle Res 15 (2013) 2055

8 Fluidized bed reactor for ALD N 2 Yakovlev, Malygin et al., J Appl Chem USSR 52 (1979) 959 Hakim, Weimer et al., Chem. Vap. Dep. 11 (2005) 420 (1 mbar) Beetstra, van Ommen et al., Chem. Vap. Product Dep. and 15 Process (2009) Engineering 227 (1 bar)

9 Introduction: ALD on fluidized powders Efficiency of precursor usage Batch and continuous reactor technology Application examples

10 Packed particle bed not efficient! Longrie et al., J. Vac. Sci. Technol. A 32 (2014)

11 Industry segment Amount of waste produced Annual product throughput [log kg] E-factor [-] Typical amount of waste [kg] Oil refining 8-10 ~0.1 1E8 Bulk chemicals 7 9 <1 5 2E8 Fine chemicals E7 Pharmaceuticals >100 5E6 Nanomaterials ,000 1E6 Sheldon, Green Chem (2007); Product Eckelman, and Process J. Engineering Ind. Ecol (2008)

12 Industry segment Amount of waste produced Annual product throughput [log kg] E-factor [-] Typical amount of waste [kg] Oil refining 8-10 ~0.1 1E8 Bulk chemicals 7 9 <1 5 2E8 Fine chemicals E7 Pharmaceuticals >100 5E6 Nanomaterials ,000 1E6 Particle ALD? 1-10 Goulas & van Ommen, KONA Powder Product and Process Particle Engineering J. 31 (2014) 234

13 Modelling precursor usage Objective: assessing the precursor utilization efficiency Conservative assumption: CSTR + PFR; re-agglomeration not considered Paper in preparation: Product and Process Grillo Engineering et al.

14 Modelling precursor usage Microscale and surface coverage dynamics

15 Simulation of residual gas analysis 1 bar 20 g TiO 2 P25 N 2 + TMA

16 -CH 3 surface coverage inside NP agglomerate Agglomerate diameter: 300 m 1 mbar 1 bar normalized coverage normalized coverage

17 TMA concentration in the bubble phase 1 bar

18 Effect of operating conditions on efficiency

19 ALD on nanoporous micron-sized particles 120 m nanoporous -alumina particles, at 1 bar normalized coverage

20 Efficiency of precursor use: exp. results 5 Deposition of Pt on TiO 2 nanoparticles Pt loading (% wt.) Amount of Pt fed to system Amount of Pt in product from ICP-OES ALD cycles 10 nm Goulas & van Ommen, J. Product Mat. and Chem. Process Engineering A 1 (2013) 4647

21 Summary modelling results ALD on NPs in FBRs: 1 bar: 100% efficiency possible, but bubbles can reduce it 1 mbar: 100% efficiency in most cases ALD on nanoporous micron-size particles: 1 bar and 1 mbar: sharp reaction fronts, lower efficiency at lab-scale, but still high (>90%) Results are in qualitative agreement with exp. findings Paper in preparation: Grillo et al.

22 Introduction: ALD on fluidized powders Efficiency of precursor usage Batch and continuous reactor technology Application examples

23 Exhaust gas neutralization system ALD reactor Precursors TMA and H 2 O Infrared Heating Lamp Control system

24 Deposition of Pt on TiO 2 nanoparticles Experimental conditions 250 mg TiO 2 P25 (Evonik), diam.: 25 nm Reactants: MeCpPtMe 3 & O 3 T = 250 o C; p = 1bar column diameter: 10 mm gas flow: 0.20 L/min / 4.2 cm/s typical pulse time: 1-10 min

25 Pt on TiO 2 nanoparticles: photocatalyst Goulas, J. Mat. Chem. A 1 (2013) 4647

26 ALD on powders simple & robust mild conditions nm to μm particles many different materials low waste footprint scalable Different reactor technologies possible: temporal spatial

27 A continuous reactor for ALD on particles 4 mm diam. 27 m long ~10 m/s ~1 g/min MeCpPtMe 3 & O 3 Pt on TiO 2 1 bar, 1 cycle Patent Pending: WO2010/100235

28 A continuous reactor for ALD on particles precursor

29 Pneumatic reactor: homogeneous product? 1 ALD cycle 10 m/s 8 m/s 4 mm 20nm 40 m/s 1 ALD cycle; 0.16 wt% Pt 8 m/s 20nm Pt on TiO 2

30 Introduction: ALD on fluidized powders Efficiency of precursor usage Batch and continuous reactor technology Application examples

31 Photocatalysis: Pt on TiO 2 nanoparticles Photocatalytic decomposition of acid blue 9 5x more active! bare TiO 2 TiO wt% Pt

32 Methylcyclohexane oxidation: Pt/TiO 2 vs Au/TiO 2 Photocatalysis with Pt/P25 (ALD) vs Au/P25 (deposition-precipitation) Time evolution of the peak height of the ketone (1710 cm -1 ) vibration catalytic catalytic + plasmonic R. Amrollahi et al., Journal Product of Catalysis and Process 319 Engineering (2014) 194

33 Suzuki-Miyaura c-c cross-coupling: Pd/Al 2 O 3 ALD of Pd with Pd(hfac) 2 and HCHO on micron-sized, nanoporous Al 2 O 3 particles 10nm Frequency (%) Pd particle size (nm)

34 Suzuki-Miyaura c-c cross-coupling: Pd/Al 2 O 3 C-C bond formation between iodobenzene and phenylboronic acid product concentration (a.u.) nm ALD cat 0.25wt.% Pd 3.4nm Commercial cat 0.53wt.% Pd 2.2nm ALD cat 0.06wt.% Pd <2.0nm Preliminary results, further investigation needed! reaction time (min) With Aris Goulas, Nastya Bavykina & Jorge Gascon

35 Opportunities for ALD in catalysis conventional & new catalysts leaching & sintering mitigation activity preservation composition & size control stability enhancement We will explore these opportunities partly in our research group, and partly via a spin-off company (as of 1/1/2015)

36 Li-ion batteries: reduced charging time & aging Sub-micron particles: faster charging, but increased aging Ultrathin coating needed to improve the lifetime 120 g powder, coated at 160 C & 1 bar Al 2 O 3 film on LiMnO 2 particles 20 nm 5 nm Normalized Discharge capacity capacity [mah/g] [-] 1,2 1 0,8 0,6 0,4 0,2 0 Uncoated 5 ALD cycles 5 ALD cycles Uncoated Charge/discharge cycle nr [-] Beetstra, Lafont, Nijenhuis, Kelder, van Ommen; Chem. Vap. Dep. 15 (2009) 227

37 quantumdot film Quantum-dot films for solar cells Solar cells based on quantum dots: theoretical efficiencies of close to 50% possible Coating needed to increase durability and efficiency ALD alumina coating alumina coating quantumdot film 100 nm substrate substrate Infilling of quantum-dot film increased efficiency with Guerra, Valdesueiro, Chandramathi Sukumaran, Houtepen

38 Conclusions Coating of fluidized particles (10 nm-1mm) with ALD at 1 bar Many different core and shell materials can be used Both continuous films & cluster growth Highly efficient use of resources Fluidized bed: scalable process Continuous process is also feasible Wide range of possibilities in catalysis, but also for other applications We will explore these via academic research + spin-off Thanks to all co-workers & students who contributed! j.r.vanommen@tudelft.nl