Turning organic waste into green gold

As early as the Stone Age, people were using the pyrolysis of wood to produce charcoal or tar. In this process (heating in the absence of oxygen), polymer chains are cracked into shorter ones that can be used as fuel. Nowadays, pyrolysis is also used to turn wood chips into valuable chemicals. University of Groningen Professor of Chemical Engineering Erik Heeres is involved in producing ‘green gold’ from organic waste.

Success

The latest success is a start-up company that he helped to launch, BioBTX. Some seven years ago, the company started working on a process that could produce benzene, toluene and xylene (BTX) from biomass. These three aromatic compounds are building blocks for the chemical industry, for example to produce plastics. ‘They can use glycerine, a by-product of biodiesel production, as feedstock,’ explains Heeres. ‘But BTX could also be produced from solid organic material, such as wood chips.’

Recently, BioBTX started to produce BTX in a small pilot plant at the Zernike Advanced Processing unit. They are only a few steps away from building an actual production plant. ‘This is a really exciting development,’ says Heeres with a broad smile. ‘In just a few years, they went from a lab bench to producing kilograms of their product.’

Catalysts

The process involved in the conversion of glycerine or wood chips into chemicals like BTX is called catalytic pyrolysis. ‘Heating organic material in the absence of oxygen produces a vapour containing different components. Adding different catalysts determines what type of components you will get,’ Heeres explains. The University of Groningen has produced a short video in which Heeres describes the success of BioBTX.

Although pyrolysis is an ancient technology, there are still improvements to be made. On 31 May, Heeres will preside over a PhD thesis defence on catalytic pyrolysis. ‘When this process is used on a factory scale, many things can go wrong. For example, the catalyst can become less active over time. And the feedstock, your starting material for the process, may affect this.’ The thesis is defended by Doug Elliot, a 66-year-old American scientist who has worked on pyrolysis for his entire career. ‘Doug worked for a government agency in the US and he never got around to doing a PhD,’ explains Heeres. ‘So, I invited him to write a thesis.’

The PhD defence is accompanied by a small symposium on pyrolysis, where the BioBTX story will also be presented, both in a talk and in a video. ‘Both Doug and BioBTX use pyrolysis to turn biomass into something useful.’ Heeres himself is working on – amongst other things – an EU project to produce bio-based kerosene through pyrolysis. ‘Airplanes will need kerosene for the foreseeable future, so the best option, in my opinion, is to produce it from renewable sources.’

Development train

It is an efficient way to use biomass. Heeres: ‘Most of us who work in this field want to stop burning biomass in power plants. That is a waste of good resources, which could be turned into highly valuable commodities.’ In the Groningen region, several start-up companies are already developing these products. BioBTX is the first to get to ‘Technology Readiness Level 5’, where the technology is being tested on a small industrial scale. ‘That is something I would like to see happening more often,’ says Heeres. ‘We now have a real ‘Green Development Train’ in this region, where all the steps from basic research to industrial production can be taken.’ It makes the Groningen region a good place to start producing green gold.