Energies (Mar 2023)

Improving the Bio-Oil Quality of Residual Biomass Pyrolysis by Chemical Activation: Effect of Alkalis and Acid Pre-Treatment

  • Gérson Daniel Valdez,
  • Flávio Pinheiro Valois,
  • Sammy Jonatan Bremer,
  • Kelly Christina Alves Bezerra,
  • Lauro Henrique Hamoy Guerreiro,
  • Marcelo Costa Santos,
  • Lucas Pinto Bernar,
  • Waldeci Paraguassu Feio,
  • Luiz Gabriel Santos Moreira,
  • Neyson Martins Mendonça,
  • Douglas Alberto Rocha de Castro,
  • Sergio Duvoisin,
  • Luiz Eduardo Pizarro Borges,
  • Nélio Teixeira Machado

DOI
https://doi.org/10.3390/en16073162
Journal volume & issue
Vol. 16, no. 7
p. 3162

Abstract

Read online

In this study, we investigated the acid (HCl) and alkali (KOH) chemical activation of açaí seeds (Euterpe Oleraceae, Mart.) pre-treatment before pyrolysis at temperatures of 350–450 °C in order to assess how reactions proceed when affected by temperature. Chemical composition of bio-oil and aqueous phase were determined by GC-MS and FT-IR. The bio-char is characterized by XRD. For the activation with KOH, the XRD analysis identified the presence of Kalicinite (KHCO3), the dominant crystalline phase in bio-char, while an amorphous phase was identified in bio-chars for the activation with HCl. The experiments have shown that bio-oil yield increases with temperature for the KOH activated biomass and decreases for the acid activated one. The KOH bio-oil is primarily composed of alcohols and ketones, showing the lowest acid values when compared with the HCl one, which is composed mainly of carboxylic acids and phenols. An increase in alcohol content and a decrease in ketones in the KOH bio-oil with temperature suggests conversion reactions between these two functions. For HCl bio-oil, carboxylic acid concentration increases with temperature while phenols decrease. For production of hydrocarbons, KOH activated biomass pyrolysis is better than acid-activated one, since no hydrocarbons were produced for HCl bio-oil.

Keywords