1. Department of Fuels Technology, Faculty of Energy and Fuels, AGH-University Science and Technology in Krakow, Al. A. Mickiewicza 30, Krakow 30-059, Poland
2. Division of Fuels Chemistry and Technology, Faculty of Chemistry, Wroclaw University of Science and Technology, Gdanska 7/9, Wroclaw 50-344, Poland e-mail: