First in the world with sustainable production of carbon black

Carbon black is one of the world's most common chemicals. It is used in the production of rubber, plastics, paint and electronics to increase durability and improve conductivity.

Alternative methods of producing carbon black are needed

Carbon black is a fine powder formed during the incomplete combustion of organic materials, typically oil or natural gas. The annual production of carbon black exceeds 10 million tonnes, resulting in carbon dioxide emissions of between 30 and 80 million tonnes. Finding a sustainable alternative to produce carbon black would greatly help with the green transition. Carbon black is a product that is 99 per cent carbon atoms. 

”This means that, when creating renewable carbon black, we still need to start with a carbon source, but we must move away from fossil raw materials. It is not possible to replace the carbon source with electricity alone, as we do when using wind, water and solar energy to replace fossil fuels in the transport sector," explains Jonas Wennebro, a research engineer at RISE in Piteå.

The operating conditions for producing carbon black are very specific. For example, it is difficult to start with a solid material such as sawdust.

"Oil works better. In addition, oil is used in most larger production facilities today, so converting production by replacing fossil oil with biogenic oil is easier,” says Jonas Wennebro.

From forest residues to green carbon black

RISE was the first organisation in the world to produce carbon black from pyrolysis oil derived from waste products from the forestry industry. Pyrolysis is a chemical process in which organic material is broken down by heat in an oxygen-free environment created by a closed reactor. The material in the reactor does not burn, but instead breaks down into gas, liquid and solid carbon. The resulting liquid is known as biogenic pyrolysis oil and can be refined into carbon black.

”This oil differs significantly in its properties from fossil oil, so we conducted basic studies funded by Formas to look at different ways of treating it to make it more suitable as a carbon black raw material. By changing the operating temperatures and retention times in the processes, it is possible to obtain different qualities,” explains Jonas Wennebro.

The researchers began with small-scale trials before scaling up the work in 2022. The existing test and demonstration facility in Piteå was expanded to increase production capacity from grams to kilograms per hour.

”This pilot is designed to mimic a commercial process for manufacturing carbon black. The increase in capacity is necessary for testing different rubber compounds to assess wear resistance, for example. This cannot be achieved by analysing a gram of carbon black under a microscope,” says Jonas Wennebro.

Users and suppliers of carbon black involved

The research team is in dialogue with rubber manufacturers and global carbon black suppliers who are interested in the progress being made at RISE in this area. In turn, the business community can contribute industry-specific knowledge about carbon black.

"There is considerable interest from industry, and suppliers are demanding bio-based carbon black made from forest raw materials, which is obviously better for the climate than using fossil fuels. At the same time, however, the forest is needed for other products. We are therefore trying to develop the most efficient and economical method of producing carbon black, converting as many of the carbon atoms from the forest raw material as possible into carbon black."

There are also potential sustainability gains in the production process itself:

”It's about how we generate the heat required in the reactor. Currently, industry mainly uses natural gas for this, whereas we are working with electric heating. In our larger pilot, we aim to use a plasma burner instead of a natural gas burner. This is based on supplying electrical energy only from sources such as nuclear power, solar power, wind power and water power. This further reduces the climate footprint. This could also be seen as a way of binding some of the carbon added to the product, making it a kind of carbon sink. We have come a long way, and now it's a matter of demonstrating that our process works on an industrial scale,” says Jonas Wennebro.