@article{TeribeleCostaSalesdaSilvaetal., author = {Teribele, Tiago and Costa, Maria Elizabeth Gemaque and Sales da Silva, Concei{\c{c}}{\~a}o de Maria and Pereira, Lia Martins and Bernar, Lucas Pinto and de Castro, Douglas Alberto Rocha and da Costa Assun{\c{c}}{\~a}o, Fernanda Paula and Santos, Marcelo Costa and de Sousa Brand{\~a}o, Isaque Wilkson and Fonseca, Cl{\´i}cia Joana Neves and Shultze, Maja and Hofmann, Thomas and Bremer, Sammy Jonatan and Machado, N{\´e}lio Teixeira}, title = {Hydrothermal Carbonization of Corn Stover: Structural Evolution of Hydro-Char and Degradation Kinetics}, series = {Energies}, volume = {16}, journal = {Energies}, number = {7}, editor = {Di Giacomo, Gabriele}, publisher = {MDPI}, issn = {1996-1073}, doi = {10.3390/en16073217}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:523-16975}, abstract = {Hydrothermal processing of biomass may be able to overcome a series of problems associated with the thermochemical conversion of lignocellulosic material into energy and fuels. Investigating the process parameters and an adequate process description is one of the first steps to being able to design and optimize a certain treatment concept. In the present article, we studied process evolution with respect to reaction time in order to evaluate structure changes and kinetics of corn stover decomposition in a hydrothermal reactor. The effect of the biomass-to-H2O ratio was also investigated. A pilot-scale reactor of 18.75 L was used to conduct hydrothermal processing runs at 250 °C at different reaction times (60, 120 and 240 min) and biomass-to-H2O ratios (1:10, 1:15 and 1:20). Solid phase products were characterized by thermogravimetry (TG), scanning electron microscopy (SEM), elemental composition (EDX), crystalline phases by X-ray diffraction (XRD) and surface area (BET). For the experiments with a constant reaction time, the yields of hydro-char, aqueous and gaseous phases varied between 31.08 and 35.82\% (wt.), 54.59 and 60.83\% (wt.) and 8.08 and 9.58\% (wt.), respectively. The yields of hydro-char and gases tend to increase with higher biomass-to-H2O ratios, while aqueous phase yields are lower when using lower ratios. As expected, the yields of liquid and gases are higher when using higher reaction times, but there is a reduction in hydro-char yields. TG showed that 60 min was not enough to completely degrade the corn stover, while 120 and 240 min presented similar results, indicating an optimized time of reaction between 120 and 240 min. SEM images, elemental composition and XRD of hydro-char showed that higher biomass-to-H2O ratios increase the carbonization of corn stover. The surface area analysis of hydro-char obtained at 250 °C, 2.0 °C/min, a biomass-to-H2O ratio of 1:10 and 240 min showed a surface area of 4.35 m2/g, a pore volume of 18.6 mm3/g and an average pore width of 17.08 μm. The kinetic of corn stover degradation or bio-char formation was correlated with a pseudo-first-order exponential model, exhibiting a root-mean-square error (r2) of 1.000, demonstrating that degradation kinetics of corn stover with hot-compressed H2O, expressed as hydro-char formation, is well described by an exponential decay kinetics.}, subject = {Biomasse}, language = {en} } @article{DanielValdezValoisBremeretal., author = {Daniel Valdez, G{\´e}rson and Valois, Fl{\´a}vio Pinheiro and Bremer, Sammy Jonatan and Bezerra, Kelly Christina Alves and Hamoy Guerreiro, Lauro Henrique and Santos, Marcelo Costa and Bernar, Lucas Pinto and Feio, Waldeci Paraguassu and Moreira, Luiz Gabriel Santos and Mendon{\c{c}}a, Neyson Martins and de Castro, Douglas Alberto Rocha and Duvoisin, Sergio and Borges, Luiz Eduardo Pizarro and Machado, N{\´e}lio Teixeira}, title = {Improving the Bio-Oil Quality of Residual Biomass Pyrolysis by Chemical Activation: Effect of Alkalis and Acid Pre-Treatment}, series = {Energies}, volume = {16}, journal = {Energies}, number = {7}, editor = {Di Giacomo, Gabriele}, publisher = {MDPI}, issn = {1996-1073}, doi = {10.3390/en16073162}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:523-16821}, pages = {1 -- 18}, abstract = {In this study, we investigated the acid (HCl) and alkali (KOH) chemical activation of a{\c{c}}a{\´i} seeds (Euterpe Oleraceae, Mart.) pre-treatment before pyrolysis at temperatures of 350-450 °C in order to assess how reactions proceed when affected by temperature. Chemical composition of bio-oil and aqueous phase were determined by GC-MS and FT-IR. The bio-char is characterized by XRD. For the activation with KOH, the XRD analysis identified the presence of Kalicinite (KHCO3), the dominant crystalline phase in bio-char, while an amorphous phase was identified in bio-chars for the activation with HCl. The experiments have shown that bio-oil yield increases with temperature for the KOH activated biomass and decreases for the acid activated one. The KOH bio-oil is primarily composed of alcohols and ketones, showing the lowest acid values when compared with the HCl one, which is composed mainly of carboxylic acids and phenols. An increase in alcohol content and a decrease in ketones in the KOH bio-oil with temperature suggests conversion reactions between these two functions. For HCl bio-oil, carboxylic acid concentration increases with temperature while phenols decrease. For production of hydrocarbons, KOH activated biomass pyrolysis is better than acid-activated one, since no hydrocarbons were produced for HCl bio-oil.}, subject = {Acai-Beere}, language = {en} }