Dong Ho Lee

Bio: Dong Ho Lee is an academic researcher from Nanyang Technological University. The author has contributed to research in topics: Pyrolysis & Sludge. The author has an hindex of 14, co-authored 16 publications receiving 6767 citations. Previous affiliations of Dong Ho Lee include Huazhong University of Science and Technology.

In-depth investigation of biomass pyrolysis based on three major components: Hemicellulose, cellulose and lignin

Abstract: To better understand biomass pyrolysis, the different roles of the three components (hemicellulose, cellulose, and lignin) in pyrolysis are investigated in depth using a thermogravimetric analyzer (TGA). The pyrolysis characteristics of the three components are first analyzed, and the process of biomass pyrolysis is divided into four ranges according to the temperatures specified by individual components. Second, synthesized biomass samples containing two or three of the biomass components are developed on the basis of a simplex-lattice approach. The pyrolysis of the synthesized samples indicates negligible interaction among the three components and a linear relationship occurring between the weight loss and proportion of hemicellulose (or cellulose) and residues at the specified temperature ranges. Finally, two sets of multiple linear-regression equations are established for predicting the component proportions in a biomass and the weight loss of a biomass during pyrolysis in TGA, respectively. The resul...

Mechanism of Palm Oil Waste Pyrolysis in a Packed Bed

Abstract: To better understand the process mechanism, pyrolysis of palm oil wastes was investigated at different temperatures in a packed bed, with focus on the changing of chemical structure and physical characteristics of solid residues and gas-releasing properties. First, three palm oil wastes were pyrolyzed with temperature increasing from the ambient to 1000 °C, and the main products from it were solid charcoal, liquid oil, and hydrogen-rich gas. The gas component mainly consisted of H2, CO2, CO, and CH4 together with trace C2H4 and C2H6. CO and CO2 evolved out at lower temperature (<450 °C), while H2 released at higher temperature (600−700 °C). Second, the decomposition property of biomass shell was analyzed at variable temperatures (300, 400, ..., 1000 °C). The pyrolysis products were thoroughly identified using various approaches (including micro-GC, FTIR, GC-MS, ASAP2010, SEM, and CNHS/O analyzer) to understand the influence of temperature on product properties and, thus, reaction mechanism involved. Start...

Pyrolysis Characteristics and Kinetics of Sewage Sludge by Thermogravimetry Fourier Transform Infrared Analysis

Abstract: The characteristics and gas product properties of pyrolyzing sewage sludge were determined, aiming to utilize efficiently the waste for energy recovery. The pyrolysis of two predried sludge materials (S1 and S2) was conducted in a thermogravimetry analyzer (TGA). It was found that the pyrolysis mainly occurred at about 150–550 °C, with two and one reaction stages found respectively for S1 and S2. Using the global reaction kinetic model, the activation energy was calculated at ∼30 kJ mol−1 in the first reaction stage for all the selected heating rates, and the pre-exponential factors increased with the increasing heating rate. The kinetic parameters calculated explained well the pyrolysis characteristics observed. In the meantime, the gas products released under different pyrolysis conditions were analyzed online using Fourier transform infrared (FTIR) spectroscopy; the results showed that the gas composition was highly dependent on temperature, and the releasing of the gas species was consistent with the ...

Dynamic molecular structure of plant biomass-derived black carbon (biochar)

Abstract: Char black carbon (BC), the solid residue of incomplete combustion, is continuously being added to soils and sediments due to natural vegetation fires, anthropogenic pollution, and new strategies for carbon sequestration (“biochar”). Here we present a molecular-level assessment of the physical organization and chemical complexity of biomass-derived chars and, specifically, that of aromatic carbon in char structures. Brunauer−Emmett−Teller (BET)−N2 surface area (SA), X-ray diffraction (XRD), synchrotron-based near-edge X-ray absorption fine structure (NEXAFS), and Fourier transform infrared (FT-IR) spectroscopy are used to show how two plant materials (wood and grass) undergo analogous but quantitatively different physical−chemical transitions as charring temperature increases from 100 to 700 °C. These changes suggest the existence of four distinct categories of char consisting of a unique mixture of chemical phases and physical states: (i) in transition chars, the crystalline character of the precursor ma...

Lignocellulosic biomass pyrolysis: A review of product properties and effects of pyrolysis parameters

Abstract: Pyrolysis is one of the thermochemical technologies for converting biomass into energy and chemical products consisting of liquid bio-oil, solid biochar, and pyrolytic gas. Depending on the heating rate and residence time, biomass pyrolysis can be divided into three main categories slow (conventional), fast and flash pyrolysis mainly aiming at maximising either the bio-oil or biochar yields. Synthesis gas or hydrogen-rich gas can also be the target of biomass pyrolysis. Maximised gas rates can be achieved through the catalytic pyrolysis process, which is now increasingly being developed. Biomass pyrolysis generally follows a three-step mechanism comprising of dehydration, primary and secondary reactions. Dehydrogenation, depolymerisation, and fragmentation are the main competitive reactions during the primary decomposition of biomass. A number of parameters affect the biomass pyrolysis process, yields and properties of products. These include the biomass type, biomass pretreatment (physical, chemical, and biological), reaction atmosphere, temperature, heating rate and vapour residence time. This manuscript gives a general summary of the properties of the pyrolytic products and their analysis methods. Also provided are a review of the parameters that affect biomass pyrolysis and a summary of the state of industrial pyrolysis technologies.