Nanocatalyst

1. Nanocatalyst U1 Rodrigo Benedetti KamalBanjara Bob DeBorde John DeLeonardis

2. What is a Catalyst? • Changes the rate of a reaction • ↑ rate: catalyst • ↓ rate: inhibitor • Does not affect equilibrium composition • Neither a product nor reactant www.pnl.gov/.../highlights/highlight.asp?id=383

3. Often specific to one reaction • Can promote one product if there are competing reactions • the catalyst can be recovered unchanged at the end of the reaction it has been used to speed up, or catalyze. www.cnms.ornl.gov/nanosci/lp10.shtm

4. How do they work? • Changes activation energy • Offers an alternative reaction pathway • New pathway requires less kinetic energy in molecular collisions

5. Types of Catalyst • Catalysts can be either heterogeneous or homogeneous, depending on whether a catalyst exists in the same phase as the substrate • Other classifications: • Electrocatalyst • Organocatalyst http://www.bnl.gov/bnlweb/pubaf/pr/photos/2009%5C05%5CPlatinumCatalyst-300.jpg

6. Common Examples • Enzymes • DNA Polymerase • Industrial catalysts • Alumina • Platinum • Catalytic converter • Platinum or rhodium 2 CO + 2 NO → 2 CO2 + N2 www.bionutrisyon.com/e-nutrients.html www.allproducts.com/.../product4.html http://maremare1225.wordpress.com/2008/03/31/sleep-with-one-eye-closed-one-eye-on-catalytic-converter/

7. Intro to Nanocatalysts http://www.news.cornell.edu/stories/Nov08/nanocatalysts.ws.html

8. Definition: ANanocatalyst is a substance or material with catalytic properties that has at least one Nanoscale dimension, either externally or in terms of internal structures1 • Generally, catalysts that are able to function at atomic scale are Nanocatalysts https://www.jyu.fi/fysiikka/en/research/material/compns/research/index_html/supported.jpg 1http://www.the-infoshop.com/report/bc21463_nanocatalysts.html

9. Growing interest • The chart below represents the number of the publish reports on nanostructured metal catalyst http://www.bepress.com/cgi/viewcontent.cgi?article=2132&context=ijcre

10. Specific metal catalyst Interest in specific elements in the preparation of Nanoparticlesin the period 2000-2007 http://www.bepress.com/cgi/viewcontent.cgi?article=2132&context=ijcre

11. Physical properties • Sizes may varies but can be controlled at less then 10 nm depending upon the application • Particle position can be controlled increasing the reaction stability and mechanism • Controllable exposed atomic structure • Uniform dispersion http://news.princeton.edu/uploads/243/image/nanocatalyst_diagram.jpg http://www.htigrp.com/data/upfiles/pdf/Nanocatalysts0304.pdf

12. Chemical Properties • Catalytic activity • Stability http://www.tacc.utexas.edu/research/users/features/stefano.php

13. Catalytic Activity • Very important factor in choosing a nanocatalyst • Porous nanostructure provides high surface to volume ratio hence increase the catalytic activity1 • Example : in a Direct Formic Acid Fuel Cells, CO poisoning significantly limits the catalytic activities of Pt/Ru and Pt/Pd alloys for formic acid oxidation • Solution to the Poisoning ; Decoding the nano particles with carbon support2 http://tinyurl.com/yzqps4d 1Nanocatalyst fabrication and the production of hydrogen by using photon energy; ming –Tsang Lee, David J. Hwang, Ralph Greif and Costas P Gigoropoulous 2References: Performance characterization of Pd/C nanocatalyst for direct formic acid fuel cells; S.HA, R. Larsen and R.I. Masel

14. Stability • Most notable property • Stability helps in achieving desire size nanopartilces with uniform dispersion on the substrate like carbon • Nanocalatyst like Pt can be stabilize by stabilizing agents like surfactants, ligands or polymers http://www.natureasia.com/asia-materials/article_images/425.jpg

15. Effect of temperature and pressure on the Nanocatalysts • Melting point may lower from the original metal species • For example: platinum has melting point is around 2000K but the nano catalyst made up of Pt has melting point around 1000K • Change in melting point have both pros and cons Pros • Possibility of using these Nanocatalysts in liquid phase • In case of fuel cells it may penetrate through the layers to increase the surface area of reaction Cons • May not be useful in some reactions • Durability may change as it might reduce the adherence capability to substrate http://www.ufz.de/index.php?en=5979 References: Dr. Balbuena; Chemical Engineering professor at TAMU

16. Advantages of Nanocatalyst • These advantages are related to the inherent properties of the material. • Also to their: • Size • Charge • Surface area http://www.inano.au.dk/research/research-areas/nano-energy-materials/nanocatalysis/

17. Size and surface area • Nanocatalyst can fit where many of the traditional catalyst will not. • By nanocatalyst being very small in size, this property creates a very high surface to volume ratio. This increase the performance of the catalyst since there is more surface to react with the reactants chemistry.brown.edu/research/sun/research.html http://www.bnl.gov/bnlweb/pubaf/pr/photos/2002/nanoparticles-w.jpg

18. Charge • Some Nanocatalyst can develop partials and net charges that help in the process of making and braking bonds at a more efficient scale.

19. Nano-catalysts are part of tomorrow’s cutting edge technology. • One example is the use of Hydrogen as a domestic fuel. As you may know, Hydrogen is as abundant as it is environmentally friendly. Companies would love to develop an efficient Hydrogen Fuel cell that is financially feasible. • One major problem however, is the method of reversible storage of Hydrogen. One company, HRL Laboratories, is currently working on a multi-million dollar project that will increase the efficiency of current Hydrogen storage methods by utilizing the properties of Nano-catalysts. A typical Hydrogen fuel cell1. Imagine filling up your tank with a gas instead of liquid2. The next slide shows the project overview

20. HRL Laboratories are working hard to meet and exceed Department of Energy standards for hydrogen storage. http://www.hydrogen.energy.gov/pdfs/review06/st_16_olson.pdf

21. Hydride Destabilization Cycle • The system cycles between Hydrogen-containing alloy and a stabilized-alloy state. • There is a lower ∆H for the stabilized alloy (where Hydrogen is destabilized). • The alloy allows for Hydrogen to become released at a lower temperature and energy level. • Nano-catalysts decrease the diffusion distance resulting in fast exchange rates making the whole process more efficient. • Nano-catalysts also can act as a scaffold for the metal hydride, allowing structure-directed agents as well as deterring particle conglomeration. http://www.hydrogen.energy.gov/pdfs/review06/st_16_olson.pdf

22. 8. 3. 7. With Nano-catalysts, many companies are on the verge of breaking through the Hydrocarbon age and transforming how we imagine energy and fuel for domestic as well as industrial purposes. 4. 6. 5.

23. Pictures cited 1.http://www.ngdir.org/SiteLinks/Kids/html/energy_mfahem_%20%20HYDROGEN.html.htm 2. http://www.fastfocus.tv/Media.aspx?id=18 3. http://www.casfcc.org/2/StationaryFuelCells/WhyFuelCells.aspx 4. http://www.netl.doe.gov/technologies/coalpower/fuelcells/seca.html 5. http://www.hydrogenics.com 6. http://www.hydrogendiscoveries.com/index.html 7. http://energiatechnologies.com/contact.asp 8. http://www.h2fc.com/Newsletter/Companies/PRs/axane_041504.html

24. Sources • Wikipedia.org • http://www.htigrp.com/data/upfiles/pdf/Nanocatalysts0304.pdf • http://www.the-infoshop.com/report/bc21463_nanocatalysts.html • Faculty member: Dr.  Perla B. Balbuena