Environmentally friendly utilization of biomass

Abstract: The thesis deals with various ways of utilization of biomass. Chapter 1 compares three biomass types: birch wood Betula sp., marine brown alga Fucus vesiculosus, and terrestrial moss Pleurozium schreberi, as precursors for preparation of biosorbents for removal of copper ions from diluted water solutions. Small sample doses (0.5 g/100ml) of the biosorbents prepared from alga and moss enabled more than 90 % removal of Cu (II) ions from diluted water solutions (5-20 mg/l). The sample from birch wood was less effective. The maximum sorption capacities (Xm) determined from the experimental equilibrium isotherms by applying the Langmuir model showed that the alga had the best copper-binding ability (Xm = 23.4 mg/g), followed by the moss (Xm = 11.1 mg/g), and the sawdust (Xm = 4.9 mg/g). The performance of the biosorbent prepared from birch was not satisfactory. The regeneration of the sorbents from alga and moss was performed using diluted HCl as eluent. No visible damages or performance losses were detected after five sorptiondesorption cycles.Chapter 2 deals with MnOx-Pd/Alumina-La catalysts for abatement of the emissions from wood combustion. Of primary interest is the calcination temperature used in preparation of the catalysts. Several catalysts are prepared using various calcination temperatures, 500, 600, 700 and 800 oC for 4 h in air and their activities and stabilities are compared. The activity tests were performed using gaseous mixtures containing combustibles representative for the flue gases from wood combustion, carbon monoxide (2500 ppm), methane (200 ppm) and naphthalene (50 ppm). The catalytic oxidation tests were performed in presence of 10 % O2, 12 % H20, 12 % CO2 and N2 (balance). The concentrations of the components in the gaseous mixture and the total flow of the mixture correspond to those in the flue gases from combustion (gas flow 2.5 l/min corresponding to a space velocity of approximately 20000 h-1). In presence of the catalysts carbon monoxide (CO) and naphthalene (C10H8) ignite almost simultaneously in the interval 150-200 ºC and are totally converted at temperatures a little above 200 ºC. The light-off temperatures of methane (CH4) are in the interval 600-650 ºC, and total conversion is reached at around 700 ºC. The most suitable calcination temperature for the catalysts prepared here is 700 ºC. Lower temperatures, 500 and 600 ºC, seem to result in formation of less stable catalysts. The catalysts calcined at higher temperature, 800 ºC, have stable performance in repeated tests, but lower activity.Chapter 3 presents results from literature study on corrosion and deposit formation in combustion of biofuels. Contributing to understanding the reasons for corrosion and the methods for its abatement are the primary goals. The scope is limited to deeper insight of the role of chlorine and alkali in combustion of biomass and the possibilities for hampering their corrosive effects. The role of additives decreasing the corrosion and deposit formation as well as the effect of water and the prospective for availability of low-chlorine biofuels have also been examined.