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Most solid fuels contain S and Cl and during their gasification, the formation of pollutants such as H2S and HCl becomes inevitable, however, a better understanding of the mechanism involved in their formation and subsequent destruction during the process could help to define operating conditions and to achieve synergy during co-gasification to minimize their emissions. The formation of these pollutants along with the partitioning of S and Cl in the gas and solid phases can be predicted using theoretical models in software packages like FactSage. If the tendency of H2S and HCl emissions predicted by the model corresponds to what has been observed, then an overall mechanism could be derived at using the thermochemical stability data. In this paper a comparison between numerical and experimental results is presented. The results obtained...
The Lisbon and surrounding area of the Lower Tagus Valley has experienced in the past the effects of
several moderate sized earthquakes that caused significant damage and destruction. They have been
attributed to local sources, though in some cases the source remains to be located. The lack of outcrops in
the flat lying Quaternary terrains, the low slip-rates of the area in connection with sedimentation and
erosion rates that erase surface ruptures are among the causes of a poor association between faults and
seismicty, which has opened way to geophysical studies. Seismic, potential-field and seismicity data have
been recently used to improve the seismic hazard evaluation of the area. In this work we complement these
studies with DTM and PSInSAR data with the purpose of obtaining an accurate evaluation of the seismic
hazard of the stud...
Hydrogen production by sodium borohydride through hydrolysis in alkaline solutions has been extensively studied as a production/storage option due to the high volumetric and gravimetric efficiency exhibited. The potential application of this option is based on an easily controllable catalysed hydrolysis reaction, non-toxic and recyclable by-products, and the high purity hydrogen produced can be used in fuel cells. This work reports on a comparative study of own-developed, supported and non-supported, nonnoble catalyst. Ru based catalysts are taken as reference. Characterization of the catalyst was accomplished using a FEG-SEM scanning electron microscope and FTIR analysis. Obtained values amount to 10 NLmin-1g-1 for Ni-based catalyst while Ru-based catalyst amount to twice as much in the same experimental conditions. Typical solutions ...
In this work was studied the effect of experimental conditions in the production of liquid
compounds from slow batch pyrolysis of mixtures of plastics, tires and pines wastes. The major
compounds formed were toluene, ethylbenzene, and linear alkanes from C5 to C10 (each reaching
yields around 5% w/w of the initial waste mixture). The pyrolysis reaction time and temperature
improved the production of those species, while decreasing heavier alkanes formation. An increase
of plastics content in waste mixture seemed to favour the production of lighter alkanes, although
this effect was not as notorious as the ones just mentioned. The styrene production decreased
regularly with the decrease of tyres content in the mixture. Autoclave initial pressure variation did
not seem to affect significantly the formation of the major compounds.
This work aimed to study the recovery of three types of waste by the process of pyrolysis: biomass, plastics and used tyres. The effects of experimental conditions in products yield and composition were studied. The increase of reaction time increased alkane content both in gas phase from 53% to 70% v/v and in liquid fraction from 48% to 60% w/w. The rise of reaction temperature led to a decrease of liquid yield (from 82% to 73% w/w), which was followed by the increase of solids and gases. The increase of reaction temperature also allowed the increase of the alkane content in gas phase from 39% to 70% v/v. The increase of initial pressure did not lead to appreciable variations in product yields or composition. The parameter that most affected products yield and composition was plastics content on the wastes initial mixture. The enhance...
In this study, waste olive cake (OC) was utilized as the raw material for the production of biosorbents by chemical treatment and its adsorption capacity for zinc ion was evaluated. Tests were conducted with the total biomass (T) and with the fraction > 2.00 mm (P), in order to determinate the influence of this fractionation step on subsequent treatments. Two chemical agents were used: sulfuric acid and sodium hydroxide. The parameters studied include physical and chemical properties of materials, contact time, pH, adsorbent dose and initial concentrations. The kinetic data were best fitted to the pseudo-second order model. Zinc binding is strongly pH dependent, with more zinc ions bound at a higher pH (5-7 in a range of 3-7). Both Langmuir and Freundlich models are well suited to fit the data on sorption of zinc by OC. Data on sorptio...
