NanocatalystU1

Rodrigo BenedettiKamal BanjaraBob DeBorde

John DeLeonardis

What is a Catalyst?Changes the rate of a

reaction↑ rate: catalyst↓ rate: inhibitorDoes not affect

equilibrium composition

Neither a product nor reactant

www.pnl.gov/.../highlights/highlight.asp?id=383

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

How do they work?Changes activation energy

Offers an alternative reaction pathwayNew pathway requires less kinetic energy in

molecular collisions

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

Common ExamplesEnzymes

DNA Polymerase Industrial catalysts

AluminaPlatinum

Catalytic converterPlatinum or rhodium2 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/

Intro to Nanocatalysts

http://www.news.cornell.edu/stories/Nov08/nanocatalysts.ws.html

Definition:A Nanocatalyst 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

1http://www.the-infoshop.com/report/bc21463_nanocatalysts.html

https://www.jyu.fi/fysiikka/en/research/material/compns/research/index_html/supported.jpg

Growing interestThe chart below represents the number of the

publish reports on nanostructured metal catalyst

http://www.bepress.com/cgi/viewcontent.cgi?article=2132&context=ijcre

Specific metal catalyst Interest in specific elements in the preparation of Nanoparticles in the period 2000-2007

http://www.bepress.com/cgi/viewcontent.cgi?article=2132&context=ijcre

Physical propertiesSizes 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://www.htigrp.com/data/upfiles/pdf/Nanocatalysts0304.pdf

http://news.princeton.edu/uploads/243/image/nanocatalyst_diagram.jpg

Chemical Properties

Catalytic activity Stability

http://www.tacc.utexas.edu/research/users/features/stefano.php

Catalytic ActivityVery important factor in choosing a nanocatalystPorous 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

2References: Performance characterization of Pd/C nanocatalyst for direct formic acid fuel cells; S.HA, R. Larsen and R.I. Masel

1Nanocatalyst fabrication and the production of hydrogen by using photon energy; ming –Tsang Lee, David J. Hwang, Ralph Greif and Costas P Gigoropoulous

http://tinyurl.com/yzqps4d

StabilityMost notable propertyStability 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

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

References: Dr. Balbuena; Chemical Engineering professor at TAMU

http://www.ufz.de/index.php?en=5979

Advantages of NanocatalystThese advantages

are related to the inherent properties of the material.

Also to their:Size Charge Surface areahttp://www.inano.au.dk/research/research-areas/

nano-energy-materials/nanocatalysis/

Size and surface areaNanocatalyst 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

ChargeSome Nanocatalyst can develop partials and

net charges that help in the process of making and braking bonds at a more efficient scale.

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.

The next slide shows the project overview

A typical Hydrogen fuel cell1.

Imagine filling up your tank with a gas instead of

liquid2.

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

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

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.

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Pictures cited1.http://www.ngdir.org/SiteLinks/Kids/html/energy_mfahem_

%20%20HYDROGEN.html.htm2. http://www.fastfocus.tv/Media.aspx?id=183. http://www.casfcc.org/2/StationaryFuelCells/WhyFuelCells.aspx4. http://www.netl.doe.gov/technologies/coalpower/fuelcells/seca.html5. http://www.hydrogenics.com6. http://www.hydrogendiscoveries.com/index.html7. http://energiatechnologies.com/contact.asp8. http://www.h2fc.com/Newsletter/Companies/PRs/axane_041504.html

SourcesWikipedia.orghttp://www.htigrp.com/data/upfiles/pdf/Nanocatal

ysts0304.pdfhttp://www.the-infoshop.com/report/bc21463_nan

ocatalysts.htmlFaculty member: Dr.  Perla B. Balbuena