Publication | Peer reviewed papers | Potentiale, Bioenergiesysteme, Logistik
Part 1─Impact of Pyrolysis Temperature and Wood Particle Length on Vapor Cracking and Char Porous Texture in Relation to the Tailoring of Char Properties
Published 06 June 2024
Citation: Maziarka P, Kienzl N, Dieguez-Alonso A, Fierro V, Celzard A, Arauzo PJ, Hedin N, Prins W, Anca-Couce A, Manyà JJ, Ronsse F. Part 1─Impact of Pyrolysis Temperature and Wood Particle Length on Vapor Cracking and Char Porous Texture in Relation to the Tailoring of Char Properties. Energy & Fuels. 6 June 2024. 38 (11): 9751 - 9771. 10.1021/acs.energyfuels.4c00937
Abstract
Pore size distribution is a key parameter in the performance of biobased pyrolytic char in novel applications. In industrial-scale production, the size of feedstock particles typically exceeds a few millimeters. For such particle sizes, it is a challenge to tailor the final properties of the char based only on the process conditions (experimental and modeling-wise). Pyrolysis studies of single particles larger than a few millimeters provide data sets useful for modeling and optimization of the process. Part 1 of this research focused on the pyrolysis of single particles of beech wood, secondary cracking, and its effect on the char porous texture. It contains a quantitative assessment of the effects of five conversion temperatures (from 300 to 840 °C) and two particle dimensions (Ø8 × 10 mm and Ø8 × 16 mm) on the composition of the pyrolysis vapors and pore morphology of the char. Results from real-time temperature and mass changes are presented along with release profiles of 15 vapor constituents measured by infrared spectroscopy. Furthermore, characterization of the collected bio-oil (using GC-MS/FID) and the textural hierarchical structured char (through N2 and CO2 adsorption, Hg porosimetry, and scanning electron microscopy (SEM)) was performed. Cracking of vapors above 500 °C was compound-specific. The polyaromatic hydrocarbons (PAHs) yield, between 680 and 840 °C, increased 5 times for 10 mm particles and 9 times for 16 mm ones. Besides temperature, PAH yield was suspected to correlate with particle length and PAHs/soot deposition in the micropores. Results showed that the macropores accounted for over 80% of the total pore volume, regardless of the temperature and particle length. Increasing the particle length by 60% caused a reduction in the specific surface area (ca. 15% at 840 °C) of the resulting char, mainly due to a reduction in microporosity. Based on the findings, the production conditions for a specific char application are suggested. The obtained data will be used in Part 2 of this research, devoted to subsequent CFD modeling of the process.