Upcycling as a climate game changer: a nanocatalyst was created at TU Wien from old batteries and aluminum foil remnants, which can be used to convertCO2 from the air into valuable methane.
Battery waste is a serious environmental problem: it contains substances that endanger both human health and ecosystems. At the same time, they also contain valuable materials such as nickel, which we urgently need - for the production of new batteries, for example. Better recycling methods for batteries are therefore urgently needed. Vienna University of Technology has now succeeded in developing a process that can be used to recover nickel from used nickel-metal hydride batteries. But that's not all: from this battery waste and used aluminum foil, as used in the kitchen, it was possible to produce a nanocatalyst that convertsCO2 from the air into valuable methane. In this way, the waste problem can be reduced and an excellent fuel can be obtained at the same time.
Battery recycling: important for the environment and the economy
"Modern batteries, such as nickel-metal hydride (Ni-MH) and lithium-ion batteries, consist of various components, which makes recycling and recovery processes technologically challenging," says Prof. Günther Rupprechter from the Institute of Materials Chemistry at TU Wien, head of the research project. "Improper disposal can lead to chemical leaks, fires and environmental pollution."
The recovery of nickel from used Ni-MH batteries is also of great economic importance: In the EU, used batteries and scrap from battery production could provide around 16% of the nickel needed by 2030, enough to equip 1.3 to 2.4 million electric vehicles (EVs) annually.
Despite this potential, current recycling capacity in the EU and the UK is only around a tenth of what will be required by 2030. Investment in recycling infrastructure is therefore needed.
Upcycling: from waste recovery toCO2 capture
"Recycling is an important step, but even greater impact can be achieved by upcycling nickel into catalysts capable of producing fuels," says Dr. Qaisar Maqbool, lead author of the study.
Conversion of battery/aluminum waste to nanocatalysts for methane production (fuel) and recycling of spent nanocatalysts to catalyst precursors (Graphic: TU Wien)The team extracted nickel from used Ni-MH batteries and produced aluminum oxide from used aluminum foil. These materials were then converted into a powerful nanocatalyst in an environmentally friendly way - using green chemistry methods.
"Our nanocatalyst consists of 92-96% aluminum oxide and 4-8% nickel, which is ideal for converting the greenhouse gasCO2 together with hydrogen into methane," explains Günther Rupprechter. The process requires neither high pressure nor high temperatures; the catalyst works at normal atmospheric pressure and an easily achievable temperature of 250°C.
From greenhouse gas to clean energy
This provides a method of convertingCO2 into a valuable fuel in a climate-neutral way: Methane plays an important role as an energy source in industry, for example. "We now want to investigate how this process can be scaled up for technological applications," says Prof. Günther Rupprechter. "We believe that this approach can change sustainable fuel production. Our approach shows a solution to the climate problem - and in a way that also helps to solve a pressing waste problem."
Recycled material can also be recycled
Many catalysts become deactivated over time - because the catalyst changes structurally at some point or becomes less effective due to the accumulation of foreign materials. No such deactivation was detected in the study. Nevertheless, it was important for the team to think in terms of closed cycles and also consider how the catalyst itself can be recycled.
"To close the sustainability loop, the used catalysts can be broken down into their original components so that they can be reused," says Dr. Qaisar Maqbool. This ensures that the entire process remains environmentally friendly and the amount of waste is minimized.
Qaisar Maqbool, Hamilton Uchenna Aharanwa, Michael Stöger-Pollach, Günther Rupprechter, Upcycling Hazardous Waste into High-Performance Ni/η-Al2O3 Catalysts forCO2 Methanation, Green Chemistry, https://doi.org/10.1039/D4GC05217J
