(316b) Impact of Precious Metal Supply and Demand on the Technology Choices for Three-Way Catalysts
AIChE Annual Meeting
2021
2021 Annual Meeting
Catalysis and Reaction Engineering Division
In Honor of Johannes Schwank's 70th Birthday (Invited Talks)
Tuesday, November 9, 2021 - 12:49pm to 1:07pm
Because of the widespread adoption of increasingly stringent emissions standards that need to be met in an increasing number of countries, there has been a recent increase in the demand for platinum group metals (PGMs). This demand has recently led to an unprecedented increase in their price, especially for Rh and Pd, the main active metals in today’s three-way catalysts (TWCs).
Current annual global vehicle usage of PGMs is roughly 9M troy oz. (toz.) of Pd, 1M toz. of Rh, and 3M toz. of Pt. The price of Pd in mid-May 2019 doubled in ten months from $1350/toz. to $2700/toz. in mid-March 2020 (pre-Covid-19 high). It is still near $2700/toz. in mid-April 2021. Over the same ten-month and thirteen-month periods the price of Rh increased nearly five times from $2900/toz. to $13,800/toz. (pre-Covid-19 high), but then kept growing to a level ten(!) times the May 2019 price ($29,800/toz) in April 2021. Conversely, other market factors have kept the price of Pt comparatively low over this same time frame near $1000/toz. Such large, rapid increases in aftertreatment cost provide difficult challenges for any car manufacturer.
The initial activity of automotive TWCs is significantly reduced by extended operation at high temperatures due to the sintering of active metal sites. Hence, automotive catalysts typically incorporate higher-than-needed initial loadings of PGMs to offset the effects of subsequent sintering. With the recent rise in PGM cost, these overloading practices are now more problematic. In the short-term, methods for replacing Pd with Pt would be interesting. The longer-term approaches that increase active metal utilization by TWCs will be discussed, such as those involving stable encapsulation of the active metal while ensuring good transport of reactant/product species. In this regard, core@shell and atomic layer deposition (ALD) approaches are potential pathways to achieving more durable PGM utilization.
Current annual global vehicle usage of PGMs is roughly 9M troy oz. (toz.) of Pd, 1M toz. of Rh, and 3M toz. of Pt. The price of Pd in mid-May 2019 doubled in ten months from $1350/toz. to $2700/toz. in mid-March 2020 (pre-Covid-19 high). It is still near $2700/toz. in mid-April 2021. Over the same ten-month and thirteen-month periods the price of Rh increased nearly five times from $2900/toz. to $13,800/toz. (pre-Covid-19 high), but then kept growing to a level ten(!) times the May 2019 price ($29,800/toz) in April 2021. Conversely, other market factors have kept the price of Pt comparatively low over this same time frame near $1000/toz. Such large, rapid increases in aftertreatment cost provide difficult challenges for any car manufacturer.
The initial activity of automotive TWCs is significantly reduced by extended operation at high temperatures due to the sintering of active metal sites. Hence, automotive catalysts typically incorporate higher-than-needed initial loadings of PGMs to offset the effects of subsequent sintering. With the recent rise in PGM cost, these overloading practices are now more problematic. In the short-term, methods for replacing Pd with Pt would be interesting. The longer-term approaches that increase active metal utilization by TWCs will be discussed, such as those involving stable encapsulation of the active metal while ensuring good transport of reactant/product species. In this regard, core@shell and atomic layer deposition (ALD) approaches are potential pathways to achieving more durable PGM utilization.