The use of biomass to produce energy is becoming more and more frequent as it helps to achieve a sustainable environmental scenario. However the exploitation of this fuel source does have drawbacks that need to be solved. In this work, the torrefaction of woody biomass (eucalyptus) was studied in order to improve its properties for pulverised systems. The process consists in a heating treatment at moderate temperature (220-300 ºC) under an inert atmosphere. The grindability of raw biomass and the treated samples was compared and an improvement in the grindability characteristics was observed after the torrefaction process. Thermogravimetric analysis of the samples was carried out in order to study their reactivity in air. The DTG curves of the torrefied biomass showed a double peak nature. The kinetic parameters were calculated for each reaction stage. The torrefaction process was found to influence the parameters of the first stage, whereas those corresponding to the second remained unaffected.

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The reduction of anthropogenic CO 2 emissions to address the consequences of climate change is a matter of concern for all developed countries. In the short term, one of the most viable options for reducing carbon emissions is to capture and store CO 2 at large stationary sources. Adsorption with solid sorbents is one of the most promising options. In this work, two series of materials were prepared from two commercial activated carbons, C and R, by heat treatment with gaseous ammonia at temperatures in the 200-800 ºC range. The aim was to improve the selectivity and capacity of the sorbents to capture CO 2 , by introducing basic nitrogen functionalities into the carbons. The sorbents were characterised in terms of texture and chemical composition. Their surface chemistry was studied through temperature programmed desorption tests and X-ray photoelectron spectroscopy. The capture performance of the carbons was evaluated by using a thermogravimetric analyser to record mass uptakes by the samples when exposed to a CO 2 atmosphere.

The thermal characteristics and kinetics of coal, biomass (pine sawdust) and their blends were evaluated under combustion conditions using a non-isothermal thermogravimetric method (TGA). Biomass was blended with coal in the range of 5-80 wt.% to evaluate their co-combustion behaviour. No significant interactions were detected between the coal and biomass, since no deviations from their expected behaviour were observed in these experiments. Biomass combustion takes place in two steps: between 200 and 360 degrees C the volatiles are released and burned, and at 360-490 degrees C char combustion takes place. In contrast, coal is characterized by only one combustion stage at 315-615 degrees C. The coal/biomass blends presented three combustion steps, corresponding to the sum of the biomass and coal individual stages. Several solid-state mechanisms were tested by the Coats-Redfern method in order to find out the mechanisms responsible for the oxidation of the samples. The kinetic parameters were determined assuming single separate reactions for each stage of thermal conversion. The combustion process of coal consists of one reaction, whereas, in the case of the biomass and coal/biomass blends, this process consists of two or three independent reactions, respectively. The results showed that the chemical first order reaction is the most effective mechanism for the first step of biomass oxidation and for coal combustion. However, diffusion mechanisms were found to be responsible for the second step of biomass combustion.

Hypercrosslinked polymers (HCPs) synthesized by copolymerisation of pdichloroxylene (p-DCX) and 4-4′-bis (chloromethyl)-1-1′-biphenyl (BCMBP) constitute a family of low density porous materials with excellent textural development. Such polymers show microporosity and mesoporosity and exhibit Brunauer-Emmett-Teller (BET) surface areas of up to 1970 m 2 g-1. The CO 2 adsorption capacity of these polymers was evaluated using a thermogravimetric analyser (atmospheric pressure tests) and a high-pressure magnetic suspension balance (high pressure tests). CO 2 capture capacities were related to the textural properties of the HCPs. The performance of these materials to adsorb CO 2 at atmospheric pressure was characterized by maximum CO 2 uptakes of 1.7 mmol g-1 (7.4 wt %) at 298 K. At higher pressures (30 bar), the polymers show CO 2 uptakes of up to 13.4 mmol g-1 (59 wt %), superior to zeolite-based materials (zeolite 13X, zeolite NaX) and commercial activated carbons (BPL, Norit R). In addition, these polymers showed low isosteric heats of CO 2 adsorption and good selectivity towards CO 2. Hypercrosslinked polymers have potential to be applied as CO 2 adsorbents in pre-combustion capture processes where high CO 2 partial pressures are involved.