A D V A N C E D M A T E R I A L S & P R O C E S S E S | J U L Y / A U G U S T 2 0 2 2 1 2 SUSTAINABILITY BRIEF MAKING PLASTIC MORE SUSTAINABLY Scientists at Cardiff University, U.K., report a new method of creating cyclohexanone oxime, a precursor to Nylon-6, a common plastic used in the automotive, aerospace, and medical industries. It is estimated that global production of Nylon-6 will reach around 9 million metric tons a year by 2024, prompting scientists to search for greener and more sustainable ways of producing cyclohexanone oxime. Currently, cyclohexanone oxime is produced industrially through a process involving hydrogen peroxide (H2O2), ammonia, and a catalyst called titanosilicate-1 (TS-1). The H2O2 used in this chemical process is producedelsewhere and needs to be shipped in before it can be used in the chemical reaction. This is a costly and carbon-intensive process that also necessitates the shipping of highly concentrated H2O2 to the end-user prior to dilution, which effectively wastes large amounts of energy used during concentration. Similarly, stabilizing agents often used to increase the shelf-life of H2O2 can limit reactor lifetime and often need to be removed before arriving at a final product, leading to further economic and environmental costs. To address this issue, the team devised a method where H2O2 is synthesized in-situ from dilute streams of hydrogen and oxygen, using a catalyst consisting of gold-palladium nanoparticles that are either directly loaded on to the TS-1 or on a secondary carrier. The method can produce yields of cyclohexanone oxime comparable to those seen in current commercial processes while avoiding the major drawbacks associated with commercial H2O2. www.cardiff.ac.uk. PLASTIC WASTE THAT ABSORBS CO2 Researchers at Rice University, Houston, led by chemist James Tour, discovered that heating plastic waste in the presence of potassium acetate produced particles with nanometer-scale pores that trap carbon dioxide molecules. According to the team, these particles can be used to remove CO2 from flue gas streams. “Point sources of CO2 emissions like power plant exhaust stacks can be fitted with this waste-plastic-derived material to remove enormous amounts of CO2 that would normally fill the atmosphere,” explains Tour. “It is a great way to have one problem, plastic waste, address another problem, CO2 emissions.” To make the material, waste plastic is turned into powder, mixed with potassium acetate, and then heated at 600°C (1112°F) for 45 minutes to optimize the nanoscale pores. The process produces a wax byproduct that can be recycled into detergents or lubricants. Pyrolyzing plastic in the presence of potassium acetate produces porous particles able to hold up to 18% of their own weight in CO2 at room temperature. The lab estimates the cost of carbon dioxide capture from a point source like post-combustion flue gas would be $21 a ton—far less expensive than the energy-intensive, amine-based process in common use to pull carbon dioxide from natural gas feeds, which costs $80- $160 a ton. Like amine-based materials, the sorbent can be reused. Additionally, it is expected to have a longer lifetime than liquid amines, cutting downtime due to corrosion and sludge formation. rice.edu. Researchers at the DOE’s National Renewable Energy Laboratory, Golden, Colo., created a solar cell with a record 39.5% efficiency under 1-sun global illumination. This is reportedly the highest efficiency solar cell of any type measured using standard 1-sun conditions. nrel.gov. Courtesy of Pixabay/CC0 Public Domain. Paul Savas feeds raw plastic into a crusher to prepare it for pyrolysis. Courtesy of Je Fitlow.
RkJQdWJsaXNoZXIy MTYyMzk3NQ==