Posts Tagged ‘Fuel Cells’
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June 3rd, 2010
The age old problem…..
Reducing the costs of platinum catalysts in fuel cells has been a goal of the US Dept of Energy’s research program for years. Its easy to be sceptical of so-called breakthroughs in this challenge, but this news reported on Nanowerk looks pretty promising, with a number of new catalyst formulations including the addition of gold to platinum.
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November 23rd, 2009
Alkaline fuel cell membranes
Alkaline fuel cells have been around for years. The Space Shuttle fuel cells (and fuel cells used on the Apollo missions before them) have all used alkaline fuel cells. This is interesting for us working in precious metals because the commonly used Nafion fuel cell membrane operates under acid conditions and requires the use of platinum electrocatalysts. However, under alkaline conditions the chemistry of the fuel cell is obviously very different and it means that the platinum group metals are not necessarily the best electrocatalysts in the fuel cell. For example, World Gold Council sponsored work a couple of years ago that showed gold electrocatalysts were very promising alternatives for oxygen reduction in fuel cells operating under alkaline conditions. However, in order to exploit this what is needed is a reliable alkaline alternative to nafion i.e. an anion exchange membrane.
In a recent development Yushan Yan, chemical and environmental engineering professor at the University of California, Riverside, and his team have developed an alkaline membrane, which contains the polymeric ionomer TPQPOH with a tris(2,4,6-trimethoxyphenyl)phosphonium unit. TPQPOH is very soluble in low-temperature water-soluble solvents, and has high ionic conductivity and alkaline stability. The membrane works on the basis of hydroxide ion exchange rather than hydrogen ion exchange. We’ll be keeping an eye on this development and what it may mean for gold in fuel cells…..
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October 27th, 2009
Ford Motor Company and Au Nanoclad™
Some weeks ago I posted on the subject of fuel cell separator plates and how gold-coated stainless steel was proven to be the best material for this application, in terms of conductivity and durability. The only issue was cost – what was need was a reduced thickness gold coating, still displaying the performance of a thicker coating.
Well, according to a presentation to be made at Fuel Cells Durability & Performance 2009 (December 8-9, 2009 · Alexandria, VA USA) The Ford Motor Company is to present on ”Nanometer Range Gold Coated Stainless Steel for Automotive Polymer Electrolyte Membrane Fuel Cell Bipolar Plate”.
Apparently, Ford is currently developing metallic bipolar plate technology with thin gold-coated stainless steel (under the brand name Au Nanoclad™) provided by Daido Steel. They claim that the use of nanometer range gold coating delivers the required electrical conductivity and corrosion resistance with least impact of cost of gold. Additionally, gold-coated stainless steel shows anodic passivation, thereby exhibiting robustness towards coating defects including surface scratches during the manufacturing of the bipolar plate. Apparently the presentation at the conference will include the ex-situ and in-situ testing data for this material.Looks like a potentially fantastic new use for gold if the fuel cell market takes off…..
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October 15th, 2009
Most-cited Energy and Fuels
I’ve just received news of the Top 20 most-cited articles published in Energy and Fuels during the last three years and the list includes ‘Chemical Fluid Deposition of Pt-Based Bimetallic Nanoparticles on Multiwalled Carbon Nanotubes for Direct Methanol Fuel Cell Application’ *. This paper describes how bimetallic formulations including platinum-gold display an efficiency to oxidize methanol to carbon dioxide at least 60% better than the monometallic Pt nanoparticle catalysts reported previously.
* Energy Fuels, 2007, 21 (4), pp 2268–2271
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September 14th, 2009
Fuel cell research funding remains
It is well known that US Energy Secretary Steven Chu’s planned to cut hydrogen research in the US and move away from the development of hydrogen and fuel cell cars. However, these plans were recently rejected by Congress and the 2010 spending bills recently approved in the House and Senate will continue funding for the programs.
According to Fuel Cell Today, the Secretary has come out saying he will work with lawmakers to ensure that the restored funding is invested wisely and suggested that he would not seek to cut funding for the programme in the next financial year. It is expected that further funding from the DOE will be forthcoming - for hydrogen production, storage, and fuel cell systems. This is good news for promising applications like palladium-gold hydrogen purification membranes which are showing real promise and gold-plated stainless steel biploar plates.
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August 11th, 2009
Separator Plates in PEM’s
It would still take a brave man to predict if and when fuel cells will enter mainstream production as an automotive power source. The remaining barriers and issues are many, and are complicated by ‘external’ influences like the price of oil. Putting that aside, if they do enter high volume production PEM fuel cells offer a potential new source of demand for gold, in a number of different fuel cell applications – as previously highlighted here. One specific fuel cell component where gold already is a material (coating) of choice is for separator plate coatings in automotive PEM fuel cells as described in this recent paper. As the author points out:
……in the aggressive fuel cell environment, corrosion of metal plates can significantly effect fuel cell performance while passivation can also lead to increased ohmic losses. The only metal plate material studied in the literature which meets the performance targets for contact resistance and corrosion is gold coated stainless steel.
As engineers focus on cost reduction it will be interesting to see if gold remains the optimum material here…
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May 8th, 2009
Hydrogen purification membranes
In the heart of the old gold mining region called Golden in Colorado, they are working on what could potentially be an important new industrial application for gold. …..Today I had a project review meeting at the Colorado School of Mines where a research group led by Prof Doug Way is further improving the alloys used in hydrogen purification using palladium membranes. This is an important technology for the emerging hydrogen economy and fuel cell power systems.
Doug Way’s team has demonstrated that the use of palladium-gold alloys in this application has clear advantages, especially with respect to reducing poisoning of the membrane with sulphur and carbon monoxide. He and his team have made great strides since his early findings and their latest results are summarised in a new publication ‘F. Roa, P.M. Thoen, S.K. Gade, J.D. Way, S. DeVoss, G.O. Alptekin, Palladium-copper and palladium-gold alloy composite membranes for hydrogen separations, in Inorganic membranes for energy and environmental applications, A.C. Bose, Editor. 2009, Springer: New York p. 221-239.’ See here.
The Wade research group will also be presenting their work on these membranes at GOLD 2009.
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March 25th, 2009
New 3M Patents on Gold Catalysts for Environmental and Chemical Applications
The team working on preparation of gold catalysts via physical vapour deposition (PVD) at 3M in the USA have had two new patents published, i.e. ‘Selective oxidation of carbon monoxide relative to hydrogen using catalytically active gold’ (WO Patent 2008/076137 A2) (PROX) and ‘Catalyst production process’ (WO Patent 2009/026035 A2). This PVD method for making gold catalysts means gold is deposited onto oxide supports in an oxidising atmosphere. They are chloride-free, and there is therefore no need for washing with water to remove unwanted chloride. Carbon can also be used as a support. These gold catalysts have characteristics useful for removing carbon monoxide from hydrogen for fuel cell feeds, and in respirators to protect users from carbon monoxide poisoning during escape from fires, etc. Other uses claimed are in vehicle and building protection, purification of exhaust gases from internal combustion engines, oxidation of carbonaceous soot in diesel exhaust streams and selective oxidation of organic compounds. The catalysts are active and durable.
Richard Holliday
David Thompson
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