Division of Environmental Physics -
Students Faculty of Mathematics, Physics and Informatics, Comenius University Bratislava
Diana RAČKOVÁ alumni student
MSc. study 2017 - 2019
Supervisor: Karol Hensel Consultant: -- Title: Napthalene removal from gas exhaust by combination of plasma and catalyst - the effect of catalyst size and specific surface area Abstract: Growing energy demand and an aversion to the use of fossils fuels due to environmental reasons have led to interest in alternative technologies and processes for heat and electricity production. Among the alternative energy sources, biomass and separated municipal solid waste have a special position due to their wide availability. The most obvious way to produce the energy from biomass is the combustion process. However, a more efficient way of obtaining energy from biomass and municipal waste is the gasification process that produce a synthesis gas but also various unwanted products as tars, fly ash, nitrogen and sulfur compounds. Tars are a mixture of condensable hydrocarbons, including aromatic compounds with one or more benzene rings, and they may cause technical problems in equipment. They also have a demonstrably negative impact on the environment and human health. The tar-contaminated gas cannot be used to generate electricity. Therefore, effective tar reduction is critical to the commercialization of biomass gasification. In this thesis we focus on removal method for tars decomposition by plasma in combination with catalytic (TiO₂ pellets) or dielectric packing material (glass beads). We built the dielectric barrier discharge reactors and used them with and without package materials. We investigated the effect of catalyst size, shape and specific surface area. Naphthalene was used as a model tar compound. In all reactors we evaluated the efficiency of naphthalene removal and we investigated the formation of gaseous and solid by-products by infrared absorption spectrometry. The results showed that plasma can effectively decompose naphthalene into water, carbon oxides, and solid by-products. When plasma is used in combination with packing material, more efficient removal has occurred, but more complex by-products have been formed. In plasma catalysis with TiO2 catalyst, naphthalene removal efficiency and selectivity of the process were found to be the most efficient. From the results it can also be concluded that the size and shape of the material is more important parameter than the specific surface area of the material.
Bc. study 2016 - 2017
Supervisor: Karol Hensel Consultant: -- Title: Naphtalene removal by combination of plasma and catalyst Abstract: Biomass differs from others renewable energy sources by the possibility of its targeted agricultural production. The most effective way to generate energy from the biomass is its gasification, that leads to production of syngas, that besides the desired gaseous components also contains ash, sulfur and nitrogen oxides and most importantly tars. Tars are a mixture of condensable hydrocarbons, usually aromatic compounds with one or more benzene rings and they may cause many technical issues in combustion equipment and have negative effects to environment and to humans. Syngas contaminated by tars cannot be used for energy production and therefore effective methods of tar decomposition have been sought. In this work, we focus on removal of tars by combination of plasma and catalyst. We constructed two identical types of reactor utilizing dielectric barrier discharge one with and one without a catalyst (TiO2 pellets). In both reactors we monitored chemical changes induced by the discharges as a function of gas mixture, composition and temperature, and amplitude and frequency of the applied voltage. We evaluated efficiency of decomposition of naphthalene, used as a model tar compound, in both reactors and analyzed by-products of its decomposition by FTIR spectroscopy. Results showed efficient decomposition of naphthalene by plasma to carbon oxides, water and solid product. Plasma catalytic system showed even better efficiency. The results proved that plasma in combination with catalyst is an efficient tool that can be used for syngas cleaning from tars and even other toxic compounds.