How to convert methane to ethylene?
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How to convert methane to ethylene?

Pulsed compression technology may enable the use of (bio)methane as a cleaner carbon feedstock by opening up a new possibility for converting methane to ethylene under non-oxidative and non-catalytic conditions. Right now, a new reactor is being built to prove that the technology can run continuously, which is the next step towards industrialization. The reactor will be constructed in the high-pressure lab of the University of Twente, where Yordi Slotboom has been busy conducting the experiments to prove the chemistry works.

For our COMPACT-project – a project that aims to convert methane to ethylene using pulsed compression technology -  ISPT has been working closely with PhD-candidate Yordi Slotboom from University of Twente. Over the past 3 years, Yordi has studied the conversion of methane to ethylene under the supervision of Sascha Kersten, head of the Sustainable Process Technology (SPT) group. We spoke to Yordi about the latest developments within the project.    

Methane conversion to ethylene by pulsed compression

Yordi Slotboom has had an interest in mathematics, chemistry and physics since high school. After completing high school, he decided to study chemical engineering at the University of Twente. “This study offered me the best of both worlds. My struggle was not wanting to work behind a computer only for the rest of my life. With chemical engineering, I got to research a lot of tangible things and work 50/50 from a lab and behind the computer.” 

In 2018, Yordi finished his master’s degree and graduated on methanol synthesis in a novel condensing reactor. Afterwards, he continued to pursue his academic career in chemical engineering by starting a PhD in methane conversion to ethylene by pulsed compression technology: the COMPACT-project. Today, Yordi is almost at the end of his PhD-track and has already hit a few important milestones. In February 2021, he published his first scientific article and in 2022 he received the NPS17 award for giving the best presentation at the conference on his work within the COMPACT-project.  

Methane is valuable carbon source

Through the span of his PhD, Yordi has worked on using new reactor technology (pulsed compression) to compete with current processes for ethylene production by converting methane. Research is currently being done to prove that it is a more energy-saving alternative with fewer CO2 emissions. The pulsed compression does not require a catalyst and therefore, does not deactivate over time. Traditionally, high temperatures are required to pyrolyze methane and to produce ethylene. Instead of the entire reactor being heated, this technology allows only the gas in the reactant chamber to increase in temperature due to the compression.  

Methane remains a valuable carbon source and it is the main component of biogas. At the same time, ethylene is widely used in the chemical industry, and its worldwide production (over 150 million tonnes in 2016) exceeds that of any other organic compound. Converting the methane to ethylene in the pulsed compression reactor is currently difficult due to high separation costs, but possibly poses a more cost-effective solution compared to conventional ethylene production with further research. By not introducing oxygen the feed is only upgraded in energy content and not partially downgraded to CO2 and water. This saves costs in separating out the CO2, water and other oxygenated species in the later stages of the process. Besides, it hopefully reduces emissions by using cleaner natural gas as a feedstock instead of naphtha. 

Pulsed compression allows us to make production more sustainable and also cheaper

Yordi Slotboom

The pulsed compression reactor  

Throughout the research, Yordi has been conducting experiments with a single shot reactor that has a pulse of 15 ms. The peak temperature is maintained shorter than 0.1 milliseconds. Yordi compares what happens inside the reactor to a car engine. “The car engine is the world’s most famous heat engine today: a car converts gasoline into motion so that it can drive. We do the same – only backwards: we convert movement into a fuel.” In this case, ethylene is produced under very unique circumstances. Traditionally, methane conversion reactors are kept at temperatures as high as 700 to 1000 degrees Celsius, whereas this reactor stays cool at 250 degrees. According to Yordi, this is a very important development for the industry: “It allows us to save energy and at the same time CO2 emissions as well. Making the production not only more sustainable, but also cheaper.”   

New reactor in development  

Currently, Yordi has been conducting the experiments with a 15-year-old reactor at his homebase, the University of Twente. However, given the feasibility for industrial applications of the COMPACT-project, a key deliverable in the project is a new reactor that can operate in a continuous mode. It is expected to start running by the end of this year. Besides, along with the valuable ethylene, other products, like for example hydrogen or propylene are produced as well. Making this project extremely valuable for moving towards a more circular industry. This is taking into account that in the future biogas becomes more available and that waste streams of plastics are (partially) converted back into methane. “To me, the transition to a circular economy is very important. By now we all know the negative effects of CO2 pollution on our climate. I believe that things have to be – and can be different in the future. To realize that, we need to make an effort to make everything as much as possible circular: reuse carbon, move to different resources and recycle our raw materials.” Using fossil methane as a carbon source means this process is not circular.  However, Yordi hopes that the technology of pulsed compression can become a small piece of the puzzle in the future.”