Pyrolysis: recycling mattresses at molecular level

Thema:
Manufacturing industry
16 September 2020

Some 1.2 million mattresses are disposed of every year in the Netherlands. Rather a lot. And recycling them is not easy; consequently, most old mattresses end up in the incinerator. This results in CO2 emissions and in the loss of raw materials. That has to change. Working in partnership with mattress manufacturers, bed suppliers, and recycling companies, TNO is currently investigating how viable the alternative method pyrolysis is.

Pyrolysis? Yes, it’s a technology in which you heat up a material to a high temperature, without adding oxygen. What happens is that the material does not burn, but disintegrates at molecular level. That, in fact, is the very point of the procedure, because it yields new raw materials for the petrochemical industry.

Propene for plastic manufacturers

‘My colleagues in Petten have carried out all the necessary tests at laboratory scale. This involved setting the pyrolysis oven at different temperatures. The heat varied from 300 to 700 degrees. And the higher the temperature, the smaller the molecules. That means that different temperatures produce different types of material. One example is propene, an important raw material in the production of plastics,’ explains Rob de Ruiter. At TNO, he is the business developer for PRIMA, the Pyrolysis Recycle Initiative for Mattresses.

‘We can use the gases that are released during pyrolysis as an energy source for the process’

Pyrolysis of old mattresses

‘When subjecting old mattresses to pyrolysis, methane and CO are also released,’ he continues. ‘That’s very useful, because we can then use that as an energy source for the process. All in all, it’s a step in the right direction for the circular economy. It does, however, raise the question of what happens when you use pyrolysis on a large scale. A pilot scheme is currently underway to find that out. At two so called pilot plants of two of the PRIMA consortium partners, Waste4me in Moerdijk and Enerpy in Delfzijl, old mattresses are already being processed in pyrolysis ovens. It is too early to come to any firm conclusions, but I understand that the results so far are very promising. So you never know – perhaps in the future there will be a special plant for old mattresses.’

‘If we, in the Netherlands, stop burning our old mattresses, we can significantly reduce CO2 emissions’

Reducing CO2 emissions

If we, in the Netherlands, stop burning our old mattresses and instead recycle them chemically, we can significantly reduce CO2 emissions. That is music to the ears of Koninklijke CBM, the professional association for the interior design and the furniture industry, and who are one of the initiators of the PRIMA project.

Pyrolysis is better than burning

As well as CBM and TNO, the whole chain is taking an active part in the project. In other words, the bed and mattress manufacturers, their suppliers, and recycling companies.

‘Anything is better than burning,’ believes Jaap Westland, commercial director at M Line. ‘So it’s great that we can use pyrolysis to extract liquids and gases from old mattresses that can then be used as raw materials. We are very keen to learn what materials are best suited for pyrolysis. We will then be able to factor that in for our own purchases.’

Recycling natural latex

‘We develop and produce our mattresses as much as possible on the basis of natural and renewable raw materials, such as natural latex, wool, and cotton. That is a deliberate choice,’ stresses Riviera Slaapcomfort director, Roel Douma.

‘Although many of these materials are naturally biodegradable, they still end up in incinerators, which just does not feel right at all. Because the recycling of natural latex still only takes place on a small scale, we are hoping that pyrolysis is the solution for making our products more sustainable. We are therefore very much looking forward to the results of all the tests and research projects.’

To learn more about TNO’s research into pyrolysis and recycling methods for old mattresses please contact Pieter Imhof.

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