Influence of temperature and particle size on structural characteristics of chars from Beechwood pyrolysis

Abstract

This work investigates the effect of temperature and particle size on the product yields and structure of chars obtained from the pyrolysis of Beechwood Chips (BWC), a lignocellulosic biomass. BWC of three different size fractions (0.21-0.50 mm, 0.85-1.70 mm and 2.06-3.15 mm) were pyrolyzed at atmospheric pressure and temperatures ranging from 300 to 900 °C in a fixed bed reactor. Tar and gas yields increased with increasing temperature, while char yield decreased, particularly between 300 and 450 °C. The effect of particle size was mostly observed at temperatures lower than 400 °C as a larger char yield for larger particles due to intraparticle reactions. At higher temperatures the larger surface area in the char fixed bed favoured reactions increasing char and gas yields from the smaller particles. Pyrolysis chars were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Raman spectroscopy. Loss in oxygenated functional groups and aliphatic side chains with increasing temperature was revealed, along with an increase in the concentration of large aromatic systems, leading to a more ordered char structure but no significant graphitization. The changes in char nature at high temperature led to a loss in their combustion reactivity. Raman spectra indicated that the temperature needed to completely decompose the cellulose structure increased with biomass particle size and the enhanced intraparticle reactions in pyrolysis of large particles was likely to give rise to amorphous carbon structures with small fused ring systems.

Optimization of Slow Pyrolysis of Bamboo for Biochar Production using Taguchi’s L9 Orthogonal Array

“…This is due to the mass transfer resistance within the solid that causes volatiles in larger particles to undergo inter-particle reactions to form char before reaching the particle surface. In contrast, least resistance is experienced in smaller particle size, leading to a higher release of volatiles and the formation of liquid and gaseous products with increasing temperatures [16,17]. In this study, the solid yield trend with increasing particle size was found consistent with literatures.…”

Co-gasification of digestate and lignite in a downdraft fixed bed gasifier: Effect of temperature

“…6 showed the parameters obtained from the Raman spectra of biochar produced at different temperatures. The digestate and lignite were rich in the O-containing functional groups and aliphatic structures, which were not likely to be converted into graphite structures at around 900 °C [54,55]. The G band and D band mainly represented the aromatic ring vibration and the aromatic ring polycondensation with 6 or more polymerized aromatic rings instead of graphite and defect structures [53,55].…”

Purification and rapid dissolution of potassium sulfate in aqueous solutions

“…This phenomenon resulted in an increase in the D and an intrinsic decrease in the h. The particle size was related to the surface area (S). [30][31][32] The particle size distribution for PLN K 2 SO 4 with 0.5% STPP/4% UP varied with crushing time as shown in Table 5. The effect of crushing time on the dissolution time is illustrated in Fig.…”