Researchers from Eindhoven University of Technology developed iron-based catalysts that captures large amounts of CO2
Researchers from the National Institute of Clean-and-Low-Carbon Energy in Beijing and Eindhoven University of Technology developed iron-based catalysts that captures large amounts of CO2 that are generated by the conversion of coal to liquid fuels (CTL) and help to reduce operating costs. The first stage in CTL process includes conversion of coal to syngas, which is a mixture of carbon monoxide (CO) and hydrogen (H2). The process is called Fischer-Tropsch process that helps to convert these components to liquid fuels. However, prior to the conversation, the composition of the syngas requires to be changed to acquire correct end products, liquid fuels. Therefore, CO is converted to CO2 through a process called ‘water-gas shift’, to reduce the amount of CO.
Chemical processing requires catalysts to enable the reactions. CTL catalysts are mainly iron based that convert around 30% of the CO to unwanted CO2, which is a byproduct that in Fischer-Tropsch process is hard to capture. This results in release of large volumes of CO2, which consumes a lot of energy without benefit. The Beijing and Eindhoven researchers found that impure iron-based catalysts cause the release of CO2. The team produced a pure form of a specific iron carbide known as epsilon iron carbide, which generates less CO2. Although, the existence of epsilon iron carbide was already known, it was not stable enough for Fischer-Tropsch process.
The researchers demonstrated that this instability is caused by impurities in the catalyst. The team developed a phase-pure epsilon iron carbide that is stable and remains functional under typical industrial processing conditions of 23 bar and 250oC. The new catalyst efficiently eliminates nearly all CO2 generation in the Fischer-Tropsch reactor. This in turn helps to reduce the energy needed and the operating costs by around US$ 30 million annually for a typical CTL plant, according to the researchers. The research was published in the journal Science Advances on October 12, 2018.