Catalytic converters are key in cutting down harmful emissions from car exhausts. Using precious metals like platinum, palladium and rhodium help trigger chemical reactions that turn toxic gases into less harmful ones.
The three-way catalytic converter was introduced in the 1980s and changed emission control by tackling carbon monoxide, hydrocarbons and nitrogen oxides. Paired with oxygen sensors that adjust the air-to-fuel ratio, this technology has greatly improved air quality worldwide. But, the catalysts themselves are becoming a problem.
Precious Metals in Catalysts
The auto industry depends on platinum group metals (PGMs). This includes mostly platinum, palladium and rhodium, and these are needed for catalytic converters, but are obviously limited and prone to price changes. Recently, a transition between platinum and palladium has occurred due to these costs, though tech advancements were also at play.
Palladium is now widely used in petrol engines, while platinum still leads in diesel engines. However, global events like the Russia-Ukraine conflict has created even more interest in platinum as a more stable option. With the industry so exposed to markets and geopolitics, it’s clear that the need for effective recycling in keeping a sustainable supply.
The Carbon Footprint of Primary PGM Mining
There’s a very energy intensive process when it comes to PGMs. Extracting just 2-6 grams of it can require processing one tonne of ore. Of course, this has sky-high CO2 emissions. According to the International Platinum Group Metals Association, around 72% of the environmental impact of PGM production is from mining and ore processing.
The low concentration of PGMs in the ore means lots of volume needs to be processed. Lots of energy is needed for drilling, blasting, crushing and refining. The depth of PGM deposits in South Africa are also an issue which need energy for ventilation and cooling.
Catalyst Recycling
Recycling catalysts is a promising way to cut the carbon footprint linked to PGM production. Studies by the International Platinum Group Metals Association show that recycled PGMs can save up to 98.5% of CO2 emissions compared to mining new PGMs. This huge reduction comes from skipping the energy-heavy mining and ore processing steps.
Recycling automotive catalysts involves two key stages: pyrometallurgical (smelting) and hydrometallurgical treatments. Smelting contributes about 65% of the carbon footprint of recycling, while refining accounts for the other 35%. Despite this, recycling’s overall impact is far lower than that of primary mining. This makes it a vital approach for the auto industry to lessen its carbon footprint.
Advanced Recycling Technologies
New recycling technologies have greatly enhanced the recovery of PGMs from catalysts. For those looking to take on the responsibility themselves, information about catalytic converter for Golf MK4 on Onlinecarparts can be found, along with tutorials on how to replace the catalytic converter.
More broadly, there have been various advancements that offer greener solutions and cost-effective options. One innovation is Molecular Recognition Technology™ (MRT™), which uses proprietary SuperLig® resins to selectively target specific PGMs, achieving single-pass recoveries of over 99% with high purity.
MRT™ helps reduce the amount of PGM tied up in processing. This lowers costs and allows for earlier metal sales. It also focuses on valuable metals like rhodium and palladium early in the process, and its closed-system design can avoid using harsh chemicals, which is a further environmental (and health) benefit.
Quantifying the Carbon Savings
A study by the International Platinum Group Metals Association highlights the significant carbon savings of PGM recycling. Recycled PGMs can cut CO2 emissions by up to 98.5% compared to primary mining. This is mainly because recycling skips the energy-intensive steps of mining and ore processing.
In the recycling process, smelting (the pyrometallurgical stage) makes up about 65% of the carbon footprint, while refining (the hydrometallurgical step) accounts for the remaining 35%. Despite these impacts, recycling’s overall environmental footprint is far smaller than that of mining, emphasizing its key role in reducing the automotive industry’s carbon emissions.
Fragmented Collection and Processing
Collecting used catalytic converters is a major challenge for the industry. One problem is the fragmented recycling chain, with tens of thousands of dismantlers and collectors in most developed countries. Coordinating this network is tricky to say the least. At best, it leads to inefficiencies, and at worst, it leads to the loss of valuable materials. The global trade of spent catalysts makes things more complicated because materials often travel across country broders a few times, which further increases its carbon footprint (and overall cost). Therefore, better coordination is needed, with bodies like the EU potentially being a force for solving this.
Regulation Is The Answer
Regulations may therefore be the answer. In the European Union, the End-of-Life Vehicles Directive (2000/53/EC) requires that 95% of a vehicle’s weight, and this of course includes catalytic converters, must be reused or recycled. This law has helped create a strong recycling infrastructure, though it doesn’t specifically target catalytic converters specifically.
The EU’s proposed Battery Regulation is helping build a circular economy though, and many are hopeful it’ll become the blueprint for future catalyst recycling. In the U.S., federal regulations are less strict, but some states like California have their own tough recycling standards. Therefore, the US arguably surfers even more from fragmented recycling practices.
