New demand for gold from diesel engine pollution control catalysts

Gold-containing exhaust emission control catalysts could provide an excellent opportunity for the gold industry. Tri-metal catalyst can outperform platinum-palladium combinations and save costs.

JOHANNESBURG - 

A new demand stream for gold could be created if recently unveiled gold-containing catalysts are applied to control diesel vehicle pollution.

Dr Richard Holliday of the World Gold Council told Mineweb that if gold became a player in the autocatalyst market for precious metals, it could be a very useful new source of demand for the metal.

The likely loadings of gold on the catalyst or the range of applications it will be used in is not known yet. But annual demand for platinum group metals in car catalysts exceeding 250 tonnes a year is some indication.

Holland said the gold industry should see this first introduction of a gold-containing catalyst for use in diesel vehicle oxidation as an excellent opportunity to create a new demand stream for gold.

Nanostellar, described as a leader in nano-engineered catalyst materials, introduced gold as an oxidation catalyst in diesel emissions technology for the first time in April this year. 

It announced a gold or tri-metal catalyst (platinum, palladium, gold) that enables manufacturers of light- and heavy-duty diesel engines to reduce harmful emissions up to 40% more than existing platinum-palladium catalysts at equal cost

Its first generation product, based on a platinum and palladium alloy, introduced in 2006, achieved a 25-30% higher performance than commercial pure platinum catalysts. And the second generation product, the gold containing catalyst, delivers a further 15-20% increase in performance.

Platinum is the most expensive component of the diesel oxidation catalysts required to meet the new, stringent emissions regulations for light-duty and heavy-duty diesel vehicles produced worldwide.

Therefore, producers of catalyst materials have introduced the use of palladium to partially replace the more expensive platinum. Now gold - about half the price of platinum - is being pioneered to further reduce the amount of platinum needed as well as the overall cost of catalysts.

The tri-metal formulation of gold, platinum and palladium in diesel catalysts allows the proportions of each metal to be adjusted to meet engine-specific performance targets and to stabilise the overall cost - despite fluctuations in the price of precious metals. 

The catalyst does not only improve on the performance of mixed platinum and palladium catalysts, but can also be more easily tuned to the characteristics of a variety of diesel engines, according to Nanostellar.

Holland added that although car manufacturers are often conservative in changing from one technology to another, the potential of cost saving would certainly act as a major enticement.

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