Tuning the performance of a DBD plasma reactor for CO2 reforming

Combatting the ever rising concentrations of greenhouse gases in the atmosphere, in particular CO2 and CH4, is one of the biggest challenges of peoplekind in this century. Reducing emissions and developing innovative solutions for capturing and reusing the gases that are inevitably produced, are the tasks at hand for the next decades. However, novel technologies are required in order to convert these greenhouse gases in a sustainable and efficient way. Plasma technology could offer a viable solution, by directly targeting the molecules in reacting into value-added chemicals. Their quick on-and-off-switching capabilities by electrical energy, in combination with intermittent renewable energy sources, makes them a promising technology to directly convert CO2 and CH4 in a sustainable way. Therefore, in this work, we studied the potential use of the DBD reactor for sustainable CO2 and CH4 conversion. We aimed to improve the reactor performance via different methods, and to develop a technique to gain more fundamental insight on how the kinetics in the reactor change on the macro scale when optimising the performance. First we investigated the influence of micrometre sized discharge gaps and packing materials to enhance CO2 dissociation conversions. The results show that smaller gap sizes are beneficial and that the performance of a packing material greatly depends on the specific combination of material composition, sphere size, and gap size. Further investigation with core-shell structured spheres showed that overall sphere properties can be optimised to a specific use. Next, an apparent first order reversible reaction fit was developed to retrieve more fundamental parameters, such as equilibrium conversion and reaction rate coefficients, on a macro level scale. By tracking the reactor conversion over a wide range of residence times for different cases and matching the results to our fit, we have elucidated how the applied power, reactor pressure, discharge gap size, and the addition of packing materials change the kinetics to influence the reactor performance in CO2 dissociation, CH4 reforming, and dry reforming of methane and their product distribution. Finally, we explored whether the reactor performance can be optimised for bi-component gas mixtures by altering the gas flow design in the reactor. The results assessed the potential of this method for dry reforming of methane and ammonia synthesis and showed room for improvement in conversion and product distribution.

Publication year:2020

Keywords:Doctoral thesis

Accessibility:Open