Introduction Currently, there are ecological and energy crises due to the increasing demand for industrialized products and personal comfort (thermal conditioning, ali- mentary needs, transport demand, etc.). The con- sumption of fossil energy sources (coal and oil) is significant considering depleting supplies. In under- developed countries, native forest territory is being lost as the original forest biomass is consumed and agricultural land borders expand. The release of pollutant carbon into the atmosphere is increasing; this carbon was previously fixed in wood, oil beds and native forest. Meanwhile, the fossil reserves will be depleted in a few decades. Due to this situation, petroleum natural gas (PNG) is beginning to be used intensely worldwide, in the past it was released into the atmosphere. The development of cheap materials for large-scale permanent fixation of carbon, while adsorbing PNG for storage and transport, is desired. There are three options for storing PNG: • the use of appropriate solvent; its drawback is the low solubility of the methane, requiring high pressures [1] • the inclusion of composites [2]; its disadvantage is the low storage capacity • the adsorption in porous materials [3–8]; that is the most promising mechanism • A lot of research is focused on the development of microporous adsorbers with a large superficial area, high packing density and good mass and heat transfer properties [9, 10]. The best choice so far is activated charcoal acting as an adsorber. Such a system can store PNG at moderate pressures (3.5 MPa), compared with the high pressures (20 MPa) required for natural gas compression [11]. Its storage capacity is in the range of 300–700 Kg m –3 , with the adsorbed/adsorbent volume rate varying from 101 to 172 V/V, whereas the ideal rate is around 150 V/V [4, 5, 7, 12–17]. The pyrolysis of vegetal organics is a common process for activating carbon. The activation of carbon can occur in some environments, such as vacuum, steam, and CO 2 , with different results on the microporosity lacking meso- and macroporosity. The maximization of the superficial area and adsorption capacity of the activated charcoal is still under study [18–20]. In this work, the pyrolysis of the Aroeira (Astronium Urundeuva), a wood of the Middle West Brazilian Biome, is presented. The samples were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Experimental Materials and methods Samples with 55×20×3 mm of heartwood of aroeira were heat treated under vacuum for 60 min. Each sample was heated at 1°C min –1 up to a different heat treatment temperature: 230, 310, 450 and 950°C. After heat treatment, the thermal behavior of about 10 mg of milled wood samples was charac- terized by DSC and TG using a Shimadzu-TA-50H, in platinum crucibles under nitrogen flow at 10°C min –1 heating rate. The experiments were repeated under dry air for 1 mg milled wood samples. 1388–6150/$20.00 Akadémiai Kiadó, Budapest, Hungary © 2008 Akadémiai Kiadó, Budapest Springer, Dordrecht, The Netherlands Journal of Thermal Analysis and Calorimetry, Vol. 93 (2008) 3, 915–919 VACUUM PYROLYSIS OF ASTRONIUM URUNDEUVA J. R. J. Delben * , P. D. Candelorio, F. F. de Oliveira, T. A. Spontoni, Angela A. S. T. Delben, M. B. Coelho and L. H. C. Andrade DFI-CCET-Universidade Federal de Mato Grosso do Sul, cx.p. 549, 79070-900 Campo Grande, MS, Brasil Petroleum natural gas (PNG) reserves will last even when the oil reserves are exhausted, requiring the development of technologies for PNG storage. Activated charcoal is the best material for such a purpose. Under vacuum samples of aroeira (Astronium Urundeuva) underwent pyrolysis in diverse conditions. The samples were characterized by thermal analysis, scanning electronic microscopy and infrared spectroscopy. When the pyrolysis temperature increased, mechanical anisotropy resistance tended to disappear. The pyrolysis became complete only at high temperatures and using a long time of treatment. Keywords: adsorption, pyrolysis, wood * Author for correspondence: delbenbr@yahoo.com.br