Conference 2018: Interview: Dr Rahul Mital

Technical Fellow, General Motors


There are predictions that diesel passenger car sales are expected to drop in the coming years, which will impact platinum usage, because diesel catalytic converters do use quite a bit of platinum. Earlier, in fact the palladium price was lower than platinum, so we were trying to use a little more palladium. Today, however, because the palladium price is at a premium, we have an opportunity to use more platinum. As diesel-car sales go down, and if platinum prices are under pressure, we actually have an opportunity to use more platinum in diesel cars. This will increase the use of platinum in diesel cars, even though diesel-car sales volumes are going down.

But then also I think that this is just a small sector of usage of platinum. Platinum is also used in the heavy-duty diesel industry, which is not going anywhere, as far as I can tell. In fact, emissions levels in that industry are also getting more stringent, so I expect more platinum usage in the heavy-duty diesel industry. On top, we have fuel-cell cars coming, which use precious metals including platinum. If the platinum price stays down and there is pressure because of the reduction in diesel-auto sales, the gasoline vehicles, which currently use no platinum, essentially, will start to consider using a little more platinum and substitute it for palladium. My thinking is that diesel-car sales will hit platinum usage a little but there are other factors globally and I do not expect platinum demand to go down significantly, if at all.

Gold has been known as a catalyst for a long time and I am sure that, even before I came into this industry, people looked at gold as an automotive catalyst. Definitely I think there is potential. Gold does provide or have limitations. It has a tendency to poison due to sulphur. It has a low melting point. In applications where we have a high temperature exposure, such as gasoline applications, it is harder to use gold. It also sinters easily. What has been done in the industry is a lot of research to figure out how to use gold, and now people have now come up with what we call tri-metal technology, combining gold with palladium and platinum, thereby providing palladium for stability and platinum for sulphur tolerance. With that tri-metal, you can use gold as a catalyst in automotive industry. Again, it is a very sophisticated tri-layer design, where we protect the gold by putting it in the bottom layer and so on.

However, currently gold is more expensive than platinum and palladium, so there is no business case today. In the future, , like it was probably between 2003 and 2008, when platinum was more expensive than gold and there was a lot of interest in doing exactly this, if that happens again I am sure people will probably come back to it and take a look and see if they can implement it in production.