The growing volume of plastic waste and the limitations of traditional waste management methods mean that circularity remains one of the key issues for the petrochemical and recycling industries. In a discussion with Clariant representatives, it was explained why plastic waste is a significant environmental problem and what role chemical recycling can play in processing streams that are not suitable for efficient mechanical recycling. As noted, more than 400 million tonnes of plastics are produced globally each year, around half of which are designed for single-use applications. If such plastics are not effectively returned to circulation, they end up in landfills or incinerators. According to data cited in the discussion, around 9% of all plastics produced to date have been recycled, while an estimated 8 to 10 million tonnes of plastic waste enter the oceans every year. The speakers also stressed that shifting from a linear model, based on producing, using and disposing of material, to a circular model can reduce CO2 emissions, because plastics recycling lowers the emissions footprint compared with the production of virgin feedstock.
The discussion pointed out that plastics recycling is significantly more complex than the recycling of glass or aluminium. Glass and aluminium can be remelted many times without significant loss of quality, whereas plastics comprise a broad group of polymers with different chemical structures, melting temperatures and additive packages. In practice, this means difficulties in jointly processing different types of materials, especially when they are mixed or contaminated with food residues, adhesives or other impurities. An additional limitation is the deterioration of properties in successive cycles of mechanical recycling. In the case of multilayer, heavily contaminated or overly heterogeneous waste, such a stream often goes to energy recovery through incineration or to landfill. As noted, from a resource perspective this means the loss of both the material and the energy originally used to produce it.
Chemical recycling as a complement to mechanical methods
Clariant representatives describe chemical recycling, also referred to as advanced recycling, as a process that breaks plastics down into their basic chemical constituents. Unlike mechanical recycling, which involves shredding and remelting the material while retaining the existing polymer chains, chemical recycling is intended to make it possible to “reset” the feedstock to a form comparable with virgin material. One of the most commonly used methods is pyrolysis, in which mixed plastic waste is exposed to high temperature in the absence of oxygen. The result is a liquid product referred to as pyrolysis oil, which, after purification, can be reused at the beginning of the plastics production chain.
The discussion emphasised that the main advantage of this route is the ability to process streams that are difficult for mechanical recycling, including mixed, contaminated and multilayer waste. At the same time, effective use of pyrolysis oil in petrochemical plants requires a very high level of feedstock purity. Among the main technical barriers identified were the variability of waste composition, the presence of contaminants such as chlorine or nitrogen compounds, and the need to ensure stable product parameters at industrial scale. According to the speakers, earlier processes were often energy-intensive, costly and did not provide the quality required by the petrochemical sector. Only the development of catalytic and sorption technologies was said to have enabled more efficient purification of such streams.
Clariant portfolio for pyrolysis oil purification
Clariant indicates that its offering for the chemical recycling of plastics is based on solutions that operate in stages. In the first stage, mineral catalysts from the Clarit Pyrolyze series are intended to support the pyrolysis process itself and lead to the production of oil with a lower content of impurities. Next, Clarit Protect adsorbents are responsible for capturing larger particles and contaminants from pyrolysis oil, serving to protect downstream refinery assets against plugging or damage.
The final stage consists of HDMax catalysts, which, according to the company, not only remove contaminants but also convert problematic compounds into forms that can be safely removed or that comply with quality requirements. The discussion explained that this concerns, among other things, chlorine compounds, nitrogen compounds and unstable molecules. The objective of the entire system is to purify pyrolysis oil to such an extent that it can be used as a feedstock compatible with crackers at existing petrochemical sites.
According to Clariant, the use of Clarit Pyrolyze is intended to improve oil quality already at the production stage, which translates into better economics and a lower burden on downstream purification stages. Clarit Protect, in turn, is intended to provide a relatively low-capex way to achieve stringent purity requirements and to act as a buffer limiting the effects of fluctuations in the quality of the incoming waste. In the company’s view, this may support the development of smaller, decentralised plastic pyrolysis plants located closer to where the waste is generated.
Importance of process integration and industrial scale
Among the key elements of its offering, the company lists a multi-stage hydrogenation process based on HDMax catalysts. According to the company, alternative solutions may require three or four separate reactors to achieve a comparable level of purification, whereas the approach proposed by Clariant is intended to deliver this effect in a single stage. According to the speakers, this translates into lower capital expenditure, lower operational complexity, reduced energy consumption and a smaller plant footprint.
In addition, the technology is intended to enable further hydrocracking to obtain hydrocarbon fractions similar to naphtha, increasing the product flexibility of the plant. In the view of the company’s representatives, such an improvement in efficiency is important for achieving the economic competitiveness of chemical recycling relative to plastics production from virgin feedstocks. The speakers also emphasise that, alongside the development of recycling technologies, reducing plastics production and consumption themselves remains equally important, because preventing waste generation is the most effective way to reduce environmental impact.
In summary, Clariant representatives point to the need for parallel development of mechanical and chemical recycling infrastructure, regulatory support, and demand for secondary raw materials and circular solutions. They also highlight the importance of proper segregation of plastic waste and purchasing choices that support the use of recycled materials.
Clarit series and adsorbents
