Researchers have developed a new process that converts plastic waste into hydrogen and carbon nanotubes. This could be used worldwide in an effort to reduce plastic pollution on land and in oceans, lakes, and rivers. (Image Credit: Antoine GIRET/Unsplash)
Plastic has become a major environmental problem over the past several decades. Today, 4.9 billion tons of plastic either sit in landfills or nature, a number that is projected to increase each year. Now, by using microwaves, chemists at the University of Oxford in the UK have created a method to convert plastic waste into a clean source of hydrogen and carbon nanotubes. The team accomplished this with a new type of catalysis that utilizes microwaves to stimulate catalyst particles to remove hydrogen from polymers. This technique is much faster than other methods and doesn’t consume a lot of energy.
Ultimately, the team wanted to help solve the issues relating to plastic waste pollution, with the UK producing 1.5 million tons every year. Since hydrogen density is approximately 14% by weight in plastic bags, plastics can be used as a source for countries looking into cleanly produced hydrogen to tackle climate change.
Other methods involve using extremely high temperatures of over 750°C to break down plastic into syngas. Then, another step is used to separate the hydrogen.
Using a kitchen blender, the team broke the plastic into smaller pieces and mixed them with aluminum oxide and iron oxide catalyst. When the mixture was heated with a microwave generator at 1000 watts, the catalyst produced hot spots in the plastic and removed the hydrogen. The conversion process lasted between 30 to 90 seconds, and 97% of hydrogen in the plastic was recovered. The leftover material was almost carbon nanotubes.
This single-step approach is advantageous because it involves heating only the catalyst, not all of the plastic. Since the plastic doesn’t absorb microwaves, it results in less energy use. Additionally, the process doesn’t have any unwanted side reactions, which makes it more efficient.
“This is not good applied science, but rather good science applied. It opens up an entirely new area of catalysis in terms of selectivity and offers a potential route to the challenge of the plastic waste Armageddon, particularly in developing countries as one route to the hydrogen economy – effectively enabling them to leap-frog the sole use of fossil fuels.” said professor Peter Edwards.
Trials have focused on using plastic that weighs just 300 grams. The team plans on using larger plastic in their experiments. This solution could be utilized in the future in an effort to reduce plastic waste pollution.
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