Formation of metal agglomerates during carbonisation of chromated copper arsenate (CCA) treated wood waste: Comparison between a lab scale and an industrial plant
ABSTRACT This paper compares the results obtained by scanning electron microscopy coupled to X-ray analysis (SEM-EDXA) of the solid product after carbonisation of treated wood waste in a lab scale and in an industrial installation. These setups (lab scale and industrial) are characterized by different operating conditions of the carbonisation process. Moreover, the wood waste input to the processes differs significantly. From this study, it is clear that some similarities but also some differences exist between the lab scale study and the study with the industrial Chartherm plant. In both reactors, a metal (and mineral) agglomeration process takes place, even in the case of untreated wood. The agglomerates initially present in the wood input may serve as a seed for the metal agglomeration process during "chartherisation". The industrial setup leads to a broader range of agglomerates' size (0.1-50 microm) and composition (all possible combinations of Cu, Cr, As and wood minerals). Some agglomerates contain the three metals but the major part is a combination of wood minerals and one or two of the three preservative metals, while all agglomerates analysed in the lab scale product contain the three metals. The separate influence of wood input characteristics and process conditions cannot be derived from these experiments, but the observations suggest that the higher the CCA retention in the wood input is, the easier is the metal agglomeration process during chartherisation of CCA treated wood waste. From the analyses performed in this study it seems that copper behaves differently in the sense that it agglomerates easily, but the resulting particles are small (<1 microm).
SourceAvailable from: Suzana Frighetto Ferrarini[Show abstract] [Hide abstract]
ABSTRACT: The species and density of Eucalyptus wood poles installed in the electrical network are useful parameters which must be considered when it is necessary to establish the service life of these structures. In this work, eucalyptus poles samples were collected and analyzed by scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS). SEM image analysis showed that the lumen diameter average of fiber substantially is variable between the three species studied, in line with the wood density obtained in laboratory, for poles with several years in service in the electricity network, as well as for not used poles. In addition, EDS microanalysis was utilized for identify the presence of chemical preservatives employed in the conservation these poles. The analysis method proposed proved effective for characterization for this timber.Materials Research 12/2013; 16(6):1428-1438. DOI:10.1590/S1516-14392013005000148 · 0.48 Impact Factor
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ABSTRACT: Gasification provides a mechanism to convert solids, such as biomass, coal, or waste, into fuels that can be easily integrated into current infrastructure. This paper discusses the use of residual char from a biomass gasifier as a catalyst for tar decomposition and presents an investigation of the catalytic properties of the char. Poplar wood was gasified in a fluidized bed reactor at temperatures ranging from 550 to 920 °C in reaction environments of 90% steam/10% N2 and 90% N2/10% CO2. The properties of the char recovered from the process were analyzed, and the catalytic performance for hydrocarbon cracking reactions was tested. Brunauer–Emmett–Teller (BET) measurements showed that the surface area of the char was higher than conventional catalyst carriers. The surface area, which ranged from 429 to 687 m2 g–1, increased with temperature and reaction time. The catalytic activity of the char was demonstrated through testing the catalytic decomposition of methane and propane to produce H2 and solid carbon. Higher char surface area resulted in increased performance, but pore size distribution also affected the activity of the catalyst, and evidence of diffusion limitations in microporous char was observed. Clusters of iron were present on the surface of the char. After being used for catalytic applications, carbon deposition was observed on the iron cluster and on the pores of the char, indicating that these sites may influence the reaction. When the char was heated to 800 °C in an inert (N2), atmosphere mass loss was observed, which varied based on the type of char and the time. ESEM/EDX showed that when char was heated to 1000 °C under N2, oxygen and metals migrated to the surface of the char, which may impact its catalytic activity. Through investigating the properties and performance of biomass gasification char, this paper demonstrates its potential to replace expensive tar decomposition catalysts with char catalysts, which are continuously produced on-site in the gasification process.Industrial & Engineering Chemistry Research 09/2012; 51(40):13113–13122. DOI:10.1021/ie3014082 · 2.24 Impact Factor
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ABSTRACT: This paper investigates the effect of copper, chromium and boron on the slow pyrolysis of CCB-treated wood. A mixture of softwood has been impregnated with several inorganic salts (individually CuSO4, KCr(SO4)2, B4Na2O7) and with salt of CCB (mixture of CuSO4, KCr(SO4)2 and H3BO3). The weight loss of samples is identified by thermogravimetric analysis (TGA). The results show a higher mass of final residue and a decrease in degradation temperature on treated wood compared to untreated wood. TGA results also show that, the maximum degradation of CCB treated wood occurs at 300 °C. In addition, slow pyrolysis experiments were carried out in a laboratory scale reactor. The pyrolysis products were quantified using analytical balance whereas gases were analyzed by gas chromatography. The trends of weight loss obtained by TGA and by laboratory scale pyrolysis are similar. Furthermore, it is observed that CCB salts inhibit the formation of CO and CO2 but promote that of H2. In the second part of this work, yield of solid pyolysis residue (charcoal) with a high metal content (Cu, Cr, B) has been carried out at 300 °C and 370 °C during residence time of 20 and 30 min. Metals in charcoal are analyzed using Inductively Coupled Plasma Mass Spectrometry. Taking into account the energy recovery of by-products, slow pyrolysis at 300 °C and 30 min appears to be optimal conditions with a high yield of charcoal about 45% and the element recovery is up to 94% of Cu, 100% of Cr and 88% of B.Journal of Analytical and Applied Pyrolysis 11/2013; DOI:10.1016/j.jaap.2013.08.002 · 3.07 Impact Factor