A comparative study on the pyrolysis of metal- and ash-enriched wood and the combustion properties of the gained char

Abstract

This study aims to investigate the pyrolysis behaviour of metal-contaminated wood and the combustion properties of char derived from wood pyrolysis. Seven metals (Na, Mg, Ca, Zn, Cd, Pb and Fe(III)) were introduced to willow in cation form by ion-exchange and the thermal behaviour of demineralised samples and samples with additional ash were also investigated. The results show that the char yield increased from 21% to 24-28% and levoglucosan yield in vapour phase decreased from 88% to 62-29% after the addition of inorganic compounds, even though the metal binding capacity of wood varied from one metal ion to another. While char yield seems to be effected mainly by the concentration of the metal ions, levoglucosan yield was more dependent on the ionic species especially when sodium ions were present. When combustion experiments were carried out with char made of the metal enriched wood, two consecutive steps were observed, both effected by the presence of inorganic compounds. The first step was identified as the release and combustion of volatiles, while the second peak of the burning profile is the actual combustion of the fixed carbon. The burnout temperatures, estimated ignition indices and the conversion indicate that the type and not the amount of metal ions were the determining factors during the second step of combustion

High resistance to thermal decomposition in brown cotton is linked to tannins and sodium content

“…The smaller activation energy in the early stage of the thermal decomposition of cellulose has been observed in the presence of natural inorganic salts (Nam et al 2014). Various metal ions introduced by ion exchange have been shown to affect the thermal behavior of cellulose (Mayer et al 2012;Richards and Zheng 1991;Soares et al 1998). The dominant role of sodium in cellulose combustion was demonstrated by the variations in HRC and char yield with the concentration of Na, K, and P, as shown in Fig.…”

“…Earlier studies (Mayer et al 2012;Richards and Zheng 1991) reported that inorganic compounds introduced to wood cellulose by ion exchange influenced its pyrolysis and combustion, depending on the types and concentration of metals present. This study showed that sodium plays an important role in lowering the thermal decomposition temperature of cellulose, which resulted in reduced oxygen consumption for combustion and increased char yield.…”

Catalytic reforming of pyrolysis tar over metallic nickel nanoparticles embedded in pyrochar

“…It showed a stable mass loss rate for the used RHC Ni from 400 to 500°C, possibly ascribed to the fixed carbon burn off. Basically, the burnout temperature of char and coke (R9) was over 500°C [44], where the mass loss rate of the used 10 g-RHC Ni decreased, compared to the used 3 g-RHC Ni and 5 g-RHC Ni. It is also indicated that hydrocarbons decomposition (R10) and carbon deposition (R11) are easier take place when a small amount of catalyst is employed.…”

Intermediate pyrolysis of biomass energy pellets for producing sustainable liquid, gaseous and solid fuels

“…It is worth noting that the barley straw pellets contain nearly twice as much ash as wood pellets (6 wt.% for barley straw compared with 3.6 wt.% for wood). Ash in the feedstock can seriously affect the yield and characteristics of char, and is considered undesirable in the feedstock (Mayer et al 2012). …”