| Abstract | Emisija hlapljivih organskih spojeva u atmosferu predstavlja jedan od najznačajnijih izvora globalnog onečišćenja zraka, a povezuje se s klimatskim promjenama zbog njihovog sudjelovanja u fotokemijskim reakcijama koje rezultiraju nastajanjem organskih aerosola, ozona i smoga. Najvažniji antropogeni izvori emisija hlapljivih organskih spojeva u okoliš su brojne kemikalije, farmaceutici, biomasa, postrojenja za proizvodnju energije, kao i sredstva za čišćenje, uredska oprema i sl. Zbog zdravstvenih problema vezanih uz većinu hlapljivih organskih spojeva, njihove emisije zakonski su regulirane, što uvjetuje primjenu različitih tehnologija za njihovo uklanjanje iz otpadnih plinova. U radu je izučavana katalitička oksidacija toluena na dopiranim CeO2 praškastim katalizatorima. Reakcija je provedena u laboratorijskom reaktoru s nepokretnim slojem katalizatora uz konstantnu početnu masu katalizatora (0,05 g), konstantnu početnu koncentraciju toluena (210,43 ppm), konstantan volumni omjer smjese toluena i dušika te zraka korištenog kao oksidans (20: 3). Katalitička oksidacija toluena provedena je pri različitim temperaturama (100-500 ⁰C) i ukupnom volumnom protoku reakcijske smjese (23-138 ml min^-1). Uspoređene su katalitičke značajke CeO2 u kojima je 10 % cerija zamijenjeno s ionom odgovarajućeg metala (Cu, Mn, Al, Cd, Fe, Ni, Zn i Co). Katalizator koji se pokazao najučinkovitijim detaljno je ispitan pri različitim prostornim vremenima. Nađeno je da dopiranje cerijevog (IV) oksida s manganom, bakrom te djelomično sa niklom i cinkom dovodi do poboljšanja aktivnosti katalizatora u odnosu na čisti (nedopiran) CeO2, što se očituje u relativno niskim temperaturama pri kojima se postiže 20 %-tna, 50 %-tna, 90 %-tna i maksimalna konverzija (T20, T50, T90 i Tmaks.). Dopiranje s aluminijem, željezom, kobaltom i cinkom rezultiralo je smanjenjem toplinske stabilnosti katalizatora odnosno sinteriranjem. |
| Abstract (english) | Emission of volatile organic compounds into the atmosphere is one of the most significant sources of global air pollution and is linked to climate change due to participation in photochemical reactions resulting in the formation of organic aerosols, ozone and smog. The most important anthropogenic sources of volatile organic compounds in the environment are numerous chemicals, pharmaceuticals, biomass, power generation plants, cleaning agents, office equipment, etc. Because of the health problems associated with most volatile organic compounds, their emissions are legally regulated, which requires the application of various technologies for their removal from the waste gases. In this paper, catalytic oxidation of toluene was studied over doped CeO2 powder catalysts. The reaction was carried out in a laboratory fixed bed reactor at a constant initial catalyst mass (0.05 g), constant initial concentration of toluene (210.43 ppm), and at a constant volume ratio of toluene in nitrogen and air used as oxidant (20:3). Catalytic oxidation of toluene was carried out at various temperatures (100-500 °C) and total volume flow of the reaction mixture of (23-138 ml min^-1). The catalytic properties of CeO2 in which 10% of cerium was replaced with ion of the corresponding metal (Cu, Mn, Al, Cd, Fe, Ni, Zn and Co) were compared. The catalyst that proved to be the most effective was tested in various spatial times. It was found out that dopping of ceria oxide with mangane and copper and in small extent with nickel and zinc leads to the increase of the catalytic activity in relation to undopped CeO2, which is reflected in relatively low temperatures at which the 20%, 50%, 90% and maximum conversions (T20, T50, T90 and Tmax) are achieved. Dopping with aluminum, iron, cobalt and zinc resulted in the decreasing of the catalyst thermal stability or catalyst sintering. |
