Investigations of wood treated by mild pyrolysis in a semi-industrial reactor for sustainable material production: thermal behavior, property changes and kinetic modeling

• Main Author: Lin, Bo-Jhih
• Other Authors: Laboratoire d'Etudes et de Recherche sur le Matériau Bois (LERMAB), Université de Lorraine (UL), LabEx ARBRE : Advanced Research on the Biology of Tree and Forest Ecosystems ( LabEx ARBRE ), Institut National de la Recherche Agronomique (INRA)-AgroParisTech-CRITT Bois-Office national des forêts (ONF)-Université de Lorraine (UL)-Centre National de la Propriété Forestière-European Forest Institute = Institut Européen de la Forêt = Euroopan metsäinstituutti (EFI), Université de Lorraine, Mathieu Pétrissans, Wei-Hsin Chen, ANR-11-LABX-0002,ARBRE,Recherches Avancées sur l'Arbre et les Ecosytèmes Forestiers(2011)
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2019
• Subjects: Pyrolysis kinetics; Thermal behavior; Devolatilization; Mild pyrolysis; Wood heat treatment; Torrefaction; Cinétique de pyrolyse; Comportement thermique; Dévolatilisation; Pyrolyse légère; Traitement thermique du bois; [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering; [SPI.MAT]Engineering Sciences [physics]/Materials; DML
• Online Access: https://hal.univ-lorraine.fr/tel-02132730; https://hal.univ-lorraine.fr/tel-02132730/document; https://hal.univ-lorraine.fr/tel-02132730/file/DDOC_T_2019_0023_LIN.pdf

Mild pyrolysis is a promising and widely applied process conducted at 200-300 °C in an inert condition to produce sustainable materials (i.e. heat treated wood) or solid fuel (i.e. torrefied wood). The aim of this study is to investigate the woods heat treated in a semi-industrial scale reactor for sustainable material production. Two different European wood species, a hardwood species (poplar, Populus nigra) and a softwood species (fir, Abies pectinata), are used to perform the experiments. The present research is divided into three parts. In the first part, the thermal behavior of wood boards is studied in a semi-industrial scale reactor. The experiments are carried out at 200-230 °C with a heating rate of 0.2 °C min-1 in a vacuum condition (200 hPa) to intensify the thermal degradation. Four different stages of thermal degradation during wood heat treatment are defined based on the intensity of differential mass loss (DML). The devolatilization characteristics of treated woods are evaluated by the devolatilization index (DI) based on the results of proximate analysis. The correlation of DI with respect to mass loss of the two wood species is strongly characterized by linear distribution, which is able to provide a simple tool to predict the mass loss of wood. In the second part of the study, a number of analyses, such as Fourier-transform infrared spectroscopy, X-ray diffraction, measurement of color change, equilibrium moisture content, and contact angle) are performed to evaluate the property changes of treated woods. The obtained results clearly demonstrate the thermal degradation through dehydration, deacetylation, depolymerization, and condensation reactions during the heat treatment. The observed phenomena of color change and hygroscopic transformation are illustrated and discussed in detail. The decarbonization, dehydrogenation, and deoxygenation of the treated woods are also evaluated. It is found that the three indexes can be well correlated to the total color difference and hygroscopicity reduction ...