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Mária CÍBIKOVÁ alumni student
MSc. study 2019 - 2021
Supervisor: Karol Hensel Consultant: Richard Cimerman Title: Selected aspects of naphthalene removal in plasma and catalyst systems Abstract: Biomass is one of the alternative sources of energy. However, conversion of biomass into energy by gasification or combustion processes produces a lot of pollutants including tars. Tars are complex compounds of mostly liquid hydrocarbons, that are highly toxic and carcinogenic, and also cause failures in industrial devices. Therefore, their removal is in high demand. There are few catalytic and thermal methods of tars removal, however energy efficiency of those methods is often very low. Plasma catalysis represents a promising method potentially useful for tars removal. Plasma is a mixture of various chemically reactive species that can react with a target compound (tar) and decompose it. Catalysis may improve energy efficiency and selectivity of the process. The combination of plasma and catalysis is often characterized by synergic effects. In such case the total effect is higher than a sum of individual effects of plasma and catalysis.
In this study we investigated plasma and plasma-catalytic reactors, their electrical characteristics including number of current pulses and their amplitudes, their chemical activity and effects on naphthalene removal as function of specific input energy (SIE) as well as temperature and the type of packing material used in the plasma-catalytic reactor. The plasma was generated in air by dielectric barrier discharge (DBD) in plasma and plasma-catalytic reactors packed with ferroelectric BaTiO3 and catalytic ZrO2 in the form of pellets. We also analysed gaseous and solid products produced during the naphthalene removal by FTIR, SEM and EDX methods. The results showed that the amplitudes and the number of pulses observed were significantly higher in the plasma-catalytic reactors when compared to the plasma reactor. The highest number and the highest amplitudes of the current pulses we observed with the BaTiO3 reactor. During the naphthalene removal at both SIE (150 J/L and 320 J/L) the best removal efficiency was found with the BaTiO3 reactor ~ 72 % and ~ 80 %. We also analysed the gaseous products produced during the naphthalene removal process by monitoring the concentration of CO. All in all, we demonstrated and proved that plasma-catalysis is a promising method for naphthalene or eventually also another tars removal.
Bc. study 2018 - 2019
Supervisor: Karol Hensel Consultant: Richard Cimerman Title: The effect of BaTiO3 a ZrO2 on naphtalene removal by plasma catalysis Abstract: Biomass is one of the alternative sources which can be used to produce energy without using fossil fuels that are harmful to a human health and have unfavorable environmental impact. Energy can be obtained by gasification or combustion processes of the biomass. The gasification leads to production of syngas, that also contains pollutants including tars. The tars inhibit the syngas utilization and it is necessary to remove them. In the process of combustion of biomass, pollutants are also produced including tars, although in much smaller amounts, but still they must be removed. Tars are a mixture of hydrocarbons with one or more benzene rings. They are highly toxic, carcinogenic, and may cause many technical problems in devices. The tars produced by gasification must be removed by using reduction process in order not to degrade the syngas. Tars formed in the combustion process can be removed also by oxidation processes as exhaust gas has no value and only gas cleaning before its release to the atmosphere is necessary.
In this study we dealed with the removal of tar by using plasma combined with ZrO2 and BaTiO3 catalysts in the form of pellets. Naphthalene was used as a model polyaromatic tar compound. Firstly we studied the electric and optical characteristics of plasma-catalytic reactors. Next we observed chemical changes in the gas caused by dicharge combined with catalyst for different frequencies and amplitudes of the applied voltage. We analyzed naphthalene removal efficiency and formation of the gaseous and solid by-products by using infrared and X-ray spectroscopy. The results show that the plasma-catalysis is more efficient in naphthalene removal as well as have better selectivity in comparison to plasma. BaTiO3 was more efficient than ZrO2 with higher frequency and lower energy were used. When tested repeatedly, BaTiO3 shown better durability and catalytic activity as well. On the other hand ZrO2 was very efficient in combination with lower frequency and had better absorption properties. Aside from that we also noticed higher production rate of desired products. In general we can conclude that plasma combined with catalyst has high efficiency and it can be considered to be effective method of tars removal.
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PhD students:
Jana KŠANOVÁ
Darina KUŽMOVÁ
Ramin MEHRABIFARD
Zuzana OKRUHLICOVÁ
Pankaj PAREEK
Gokul SELVARAJ
Sergei SMIRNOV
Peter TÓTH
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