【Haichuan Technology News】With advanced steam cracking, all plastic waste can be turned into new high-quality plastics
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A research team at Chalmers University of Technology in Sweden has developed an effective method to break down any plastic waste at the molecular level, after which the resulting gases can be converted back into new plastic with the same quality as the original plastic. This new process can transform today’s plastic plants into recyclable refineries within the framework of their existing infrastructure. Plastics do not decompose, so they continue to accumulate in our ecosystems, which is one of the major environmental problems on Earth. However, a research team led by Henrik Thunman, a professor of energy technology at Chalmers University of Technology, views plastic as an asset. The fact that it does not degrade allows it to be reused, thereby creating real value from waste plastics and ultimately providing an economic incentive for its collection.
Professor Thunman said, “We should not forget that plastic is a wonderful material that provides us with the products we have always dreamed of.” The problem is that its production cost is so low; it’s even cheaper to produce new plastics from oil and fossil gases, and we don’t recycle plastic waste. ” Now, through chemical recycling experiments involving the steam cracking of plastics, researchers have developed an effective method to convert waste plastics back into plastics of their original quality. Professor Thunman said, “By finding the right temperature (around 850 degrees Celsius), as well as the appropriate heating rate and residence time, we have been able to convert 200 kilograms of plastic waste per hour into a useful gas mixture, which can then be recycled at the molecular level to become new plastic materials of the same quality as the original ones.” ” The experiment was conducted at the Chalmers Power Center plant in Gothenburg.
Professor Thunman said, “We focus on capturing carbon atoms from the collected plastics and using them to create new plastics of the same quality as the original ones; in other words, we move back to the top of the waste hierarchy, thereby achieving true circularity.” ” Today, new plastics are made by crushing fossil oil and natural gas fractions in equipment called “crackers” in petrochemical plants. Building blocks composed of simple molecules can be combined to form many different structures, which results in the existence of a wide variety of plastics in society. Advanced steam cracking process flow diagram: To achieve the same results with recycled plastics, new processes need to be developed. The researchers at Chalmers have demonstrated an economical design process. Ultimately, this technology can enable today’s petrochemical plants to undergo a significant transformation into future recycling refineries. The researchers are continuing their research. Professor Thurnman said, “We are moving from preliminary tests to prove the feasibility of this process toward a more detailed understanding.” This knowledge is necessary to scale up the process from a few tons of plastic per day to hundreds of tons. If it succeeds, it will be the time for this technology to be commercialized. ” This process is suitable for all types of plastics, including those that have historically been stored in landfills or at sea.
In 2017, Sweden’s total plastic waste amounted to around 1.6 million tons, of which only about 8% was recycled to be used in low-quality plastics. Researchers see opportunities in recycling plastics, as it allows us to break free from the reliance on oil and fossil gases needed to produce various high-quality plastics. Professor Thunmann said, “Recycling will give waste plastics real value, thereby creating an economic incentive to collect waste plastics anywhere in the world.” Conversely, this will help to minimize the release of plastics into nature and create a market for areas that have already been polluted by waste plastics. ” Waste bio-based materials, such as paper, wood, and clothing, can also be used as raw materials in chemical processes. This means we can gradually reduce the proportion of fossil materials in plastics. If carbon dioxide is also captured in this process, we may achieve net negative emissions as well. The vision for the future is to create a sustainable recycling system for carbon-based materials.
In 2015, approximately 350 million tons of plastic waste were generated worldwide. A total of 14% of the plastic was recycled, of which 8% was recycled as plastic of lower quality, while 2% was recycled as plastic with a quality similar to that of the original material; approximately 4% was lost in this process. Overall, 40% of the plastic waste collected globally in 2015 was processed after collection, mainly through incineration for energy recovery or volume reduction, thereby releasing carbon dioxide into the atmosphere. The remaining approximately 60% of waste plastics is landfilled. Only about 1% of plastic waste is not collected and ends up in the natural environment. Although it accounts for only a small percentage, this remains a serious environmental problem, as the total amount of plastic waste is so large and the natural degradation of plastic is so slow, resulting in its accumulation over time.
The approach of recycling and reprocessing waste materials has indeed made progress; what’s important is the available process technologies and economic viability. People will continue to work hard to make it a reality
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