Catalysis 2025 Issue

Can pyrolysis oil unlock greater plastic circularity?

Combining pyrolysis and vapour-phase catalytic upgrading offers lower temperature and energy requirements, higher yields, and optimised product distribution and selectivity

Markus Hartung Evonik Catalysts

M uch of our society is dependent on plastics, with the first synthetic plastics manufactured more than 150 years ago. Plastics made the development of computers, cell phones, and advances in modern medicine possible. Food production, transport, and power rely on plastic for efficiency and safety, while our possessions are cheaper, lighter, stronger and safer. It is no wonder that plastic production is increasing expo - nentially. Between 1950 and 2018, consumption grew about 180 times, from two million tons to 368 million tons. The UN Environment Programme (UNEP) states that 430 million tons of plastic are produced each year; production is expected to double yet again by 2050. However, the repu - tation of plastics has suffered in recent decades due to envi- ronmental and public health concerns. Looking at start-of-life, approximately 98% of single-use plastic produced today comes from fossil fuels. About 4% of global oil and gas production is being used as feedstock for plastics, while 3-4% is used to provide energy for the manu - facture of plastics. A 2021 report found none of the 100 larg - est plastic producers procure more than 2% of their feedstock from recycling sources, presenting a window for opportunity. Criticism of plastics has largely been directed towards end-of-life management. A third of plastics are single-use; if we look specifically at the plastic used in packaging, about 95% of its material value is lost after a short first-use cycle, representing an $80-120 billion missed opportunity. The amount of plastics that end up in landfill, incinerated, or leaked into the environment stands at 72%, and the rate of successful plastic recycling sits at a reported 9%. Emissions from plastic production and disposal are expected to double in the next 35 years. A more circular economy is needed to improve the current state of these bespoke statistics. Chemical recycling has been touted as part of the solution, with one particular method, pyrolysis, gaining interest internationally and offering a route to de-fossilising raw material streams into refineries. Organic material, including biomass, waste, tyres, and especially plas - tics, is transformed into pyrolysis (pyrolytic) oil or gas, which can be repurposed and utilised as reusable crude oils. Plastic recycling status There is no single reason behind low recycling rates; they stem from multiple factors. One significant challenge is

the make-up of many individual plastic products using materials such as flexible films, multilayer materials, and coloured plastics, which cannot be recycled with conven - tional mechanical recycling or are entirely non-recyclable. Despite this, industries and legislators face growing public pressure to increase the collection, recycling, and reuse of all plastics. However, varied international management of the problems also presents a barrier to this. In European Organisation for Economic Co-operation and Development (OECD) countries, the annual plastic waste generated per person is 114 kg. In the US, annual plastic waste generation is 221 kg per person, while Australia generates 148 kg per person. In the UK, figure for 2021 was reported at 99 kg per person. The Asian continent is the largest plastic waste producer, and individual Asian countries can vary widely in plastic waste rates. Developing countries in South and Southeast Asia are major destina - tions for waste exports, particularly from the EU and US. There is no dedicated international instrument in place for plastics recycling today. Some countries are taking action to reduce plastic consumption or increase recycling through campaigns and awareness-raising measures. Other coun - tries have specific laws in place, obliging businesses to minimise waste, adopt recycling targets, and phase out single-use plastics. The EU aims to ban single-use plas - tics by 2030 and cut the amount of plastic packaging by 15% by 2040. Australia mandated that 100% of plastic be recycled or reused by 2040. However, the country’s largest soft-plastics recycling scheme collapsed in 2022. Collection of waste differs between developed econ - omies, where recyclable waste is typically collected by waste management companies and sorted and cleaned with equipment, and developing countries, which often rely on human waste pickers. The US faces difficulty because its systems for collection and management of plastics waste are organised at state and regional levels, but they are highly variable. In many Asia Pacific countries, the main drivers of plastic pollution are inadequate waste collection and processing infrastructures. The primary existing method of plastic recycling, an industry standard, is mechanical recycling. Established on an international scale and around for decades, mechani - cal recycling sees plastic waste processed into secondary raw materials or products without chemically disrupting

Catalysis 2025