Chemical recycling comprises various processes for processing plastic waste into chemical base materials and chemical precursors. The molecular chains of the plastics (polymers or polymer chains) can be broken down using various methods: liquefaction by pyrolysis, conversion into gas, or the decomposition of the plastics into their chemical building blocks (monomers).

In recent years, thermochemical recycling (pyrolysis) has become the most promising of the chemical recycling processes. In this method, organic compounds are broken down into small molecules by literally "cooking" the plastic at high temperatures (300 °C to 700 °C) in the absence of oxygen and breaking it down into shorter hydrocarbon chains. This results in the formation of oil-like liquids (pyrolysis oil) and gas mixtures. The pyrolysis products can then be used to produce new chemicals and materials for high-quality plastics.

To ensure that the recycled oil is suitable for further processing into new chemicals, new plastic products or fuels, its content of carbon, hydrogen, nitrogen, oxygen and sulfur – or CHNOS for short - must be measured in a qualified manner. While CHNS analysis of fossil raw materials has been carried out for decades, the need for oxygen analysis is new and specific to raw material recycling. Our elemental analyzers for CHNOS analysis, such as the vario EL cube and the rapid OXY cube®, help with the important task of quality control of pyrolysis oil. Through thermal decomposition (O) or combustion (CHNS) of the pyrolysis oil, the CHNOS contents of the sample are reliably converted into the target analyte gases, which are measured with our highly sensitive detectors, so that the exact chemical composition of the recycled materials can be determined easily and quickly.

Admittedly, the chemical recycling of plastics is still in its infancy, but it is already an important building block in the transition to a circular economy and it is much more environmentally friendly than the incineration of plastic waste, which unfortunately still dominates. There are two main application areas for chemical recycling: firstly, where mechanical recycling reaches its limits, for example when the effort involved in sorting and cleaning is too great. Secondly, chemical recycling makes sense when the material has already been mechanically processed several times. If you want high-quality recycled materials, then you need chemical recycling so that the polymer can be broken down into its components and then reassembled.

We are hopeful that the further development of pyrolysis techniques will be successful, as pyrolysis is an important breakthrough on the road to a circular economy for plastics. Our elemental analyzers for CHNOS analysis play a key role in refining chemical recycling techniques and accurately assigning recycling labels to products. CHNOS analysis of pyrolysis oil can help to optimize pyrolysis technologies by providing a quick and easy way to check whether small changes lead to an even more valuable product.

In this way, we hope elemental analysis can contribute to finally getting the global plastic waste problem under control!