Slow pyrolysis of xylan as pentose model compound for hardwood hemicellulose: A study of the catalytic effect of Na ions

04/12/2018

In this study, the effect of sodium (Na) ions on the slow pyrolysis of hemicellulose is assessed using xylan as a representative of hardwood hemicellulose. Thermogravimetric analysis and pyrolysis tests were conducted at slow heating rates (5 K/min) up to 973 K on commercial xylan, demineralized xylan and Na+ doped xylan samples. Commercial xylan was demineralized by using a cation-exchange resin to reduce the presence of inherent inorganics (mainly alkali or alkaline-earth metals). Subsequently, the demineralized xylan was doped with controlled amounts of Na ions (0.4, 0.5 and 1.1 wt.%) by using cation-exchange resin in Na+ form. The pyrolysis products yields (gas, liquid and char) and the composition of the gas mixture were quantified for each sample. Gas chromatography/mass spectrometry (GC/MS) analysis were performed to quantify the main species in the liquid products. The results, discussed considering of the available hemicellulose pyrolysis models, demonstrate that the presence of Na+ greatly affects the pyrolytic behavior of the samples, whereas only slight quantitative effects are observed on the solid residues yields, which increase with Na+ concentration. Furthermore, Na+ favors the ring opening reactions (increasing the production of CO2, CO and hydroxy ketones) and the rearrangement of the xylose ring to form furan derivatives. The reaction pathways competing with 2-furaldehyde production mechanism could explain the non-monotonous trend of this compound as function of Na+ content.

Autores da comunidade :

• 

  A

  Ana Isabel Marques Ferreiro

  ist168476

  Afiliações e fontes

  IST > IDMEC

  Instituto de Engenharia Mecânica

• 

  M

  Miriam Estefânia Rodrigues Fernandes Rabaçal

  ist154586

• 

  M

  Mário Manuel Gonçalves da Costa

  ist13384

  Afiliações e fontes

  IST > IDMEC

  Instituto de Engenharia Mecânica

  IST > LAETA

  Laboratório Associado de Energia, Transportes e Aeronáutica

  IST > DEM

  Departamento de Engenharia Mecânica

AO - Versão original do autor

Elsevier

https://www.sciencedirect.com/science/article/pii/S0165237018309409

Journal of Analytical and Applied Pyrolysis

266

275

137

10.1016/j.jaap.2018.12.004

mechanical-engineering - Engenharia Mecânica

Palavras-chave

• Xylan
• Hemicellulose
• Pyrolysis
• Demineralization
• catalysis
• Na

eng - Inglês

CC-BY-NC-ND - CC-BY-NC-ND