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

Abstract

This work investigated the effect of temperature and acid or alkalis chemical activation by pyrolysis of Açaí seeds (Euterpe Oleraceae, Mart.) on the yield of bio-oil, hydrocarbon content of bio-oil, and chemical composition of aqueous phase. The experiments were carried out at 350, 400, and 450 °C and 1.0 atmosphere, KOH and HCl activation, in laboratory scale. The acidity of bio-oils and aqueous phases determined by AOCS methods, while the chemical composition of bio-oils and aqueous phase by GC-MS and FT-IR. The bio-char 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 yield of bio-oil, for the pyrolysis of Açaí seeds activated with KOH, varied between 3.19 and 6.79 (wt.%), showing a smooth exponential increase with temperature. The acidity of bio-oil varied between 12.3 and 257.6 mgKOH/g, decreasing exponentially with temperature, while the acidity of aqueous phase lies between 17.9 and 118.9 mgKOH/g, showing and exponential decay behavior with temperature, demonstrating that higher temperatures favor not only the yield of bio-oil but also bio-oils with lower acidity. For the pyrolysis experiments activated with HCl, the yield of bio-oil varied between 2.13 and 3.37 (wt.%), decreasing linearly with temperature, while that of gas phase varied between 17.91 and 37.94 (wt.%), increasing linearly with temperature. The acidity of bio-oil varied between 127.1 and 218.5 mgKOH/g, increasing with temperature, showing that higher temperatures did not favor the yield of bio-oil and bio-oils acidity. For the chemical activation with KOH, the FT-IR analysis of bio-oils identified the presence of chemical groups characteristics of hydrocarbons and oxygenates, while that of aqueous phase only groups characteristics of oxygenates. For the chemical activation with HCl, the FT-IR analysis of bio-oil and aqueous phases identified only the presence of groups characteristics of oxygenates. For the experiments with KOH activation, the GC-MS of bio-oil identified the presence of hydrocarbons (alkanes, alkenes, cycloalkanes, cycloalkenes, and aromatics) and oxygenates (carboxylic acids, phenols, ketones, and esters). The concentration of hydrocarbons varied between 10.19 to 25.71 (area.%), increasing with temperature, while that of oxygenates from 52.69 to 72.15 (area.%), decreasing with temperature. For the experiments with HCl activation, the GC-MS of bio-oil identified only the presence of oxygenates. Finally, it can be concluded that chemical activation of Açaí seeds with KOH favors the not only the yield of bio-oil but also the content of hydrocarbons while activation with HCl produced bio-oils with only oxygen compounds.

Depolymerization of PMMA-Based Dental Resin Scraps on Different Production Scales

“…All three fixed bed pyrolysis plants were accurately described in previous works [9,[55][56][57][58][59][60][61][62][63]. Basically, the three reaction systems are constructed based on a classic semibatch pyrolysis system (Figure 2) composed of a heated temperature-controlled fixed bed reactor coupled with a tube condenser operating with cooling water.…”

“…Basically, the three reaction systems are constructed based on a classic semibatch pyrolysis system (Figure 2) composed of a heated temperature-controlled fixed bed reactor coupled with a tube condenser operating with cooling water. The condensate and gases are separated in another vessel, where the liquid fraction is collected and the non- All three fixed bed pyrolysis plants were accurately described in previous works [9,[55][56][57][58][59][60][61][62][63]. Basically, the three reaction systems are constructed based on a classic semi-batch pyrolysis system (Figure 2) composed of a heated temperature-controlled fixed bed reactor coupled with a tube condenser operating with cooling water.…”

Improving the Yield and Quality of Bio-Oil from Açaí Seeds Pyrolysis by Activation with KOH: Effect of Temperature and Molarity

“…The impregnation process was conducted at room temperature. The formed suspension was then transferred to a paper filter, washed with 120 mL of distilled water, and left to rest for 24 hours, following a previously described method [31]. Subsequently, it was dried at 100 °C ± 5 °C for 24 hours.…”

“…Although research has been conducted on the pyrolysis of residual Açaí seeds [8,11,[17][18][19][20][21][22][23][24][25][26][27][28][29][30][31], most of these studies have focused on producing activated carbon/bio-adsorbents [8,[17][18][19][20][21][22][23][24][25][26][27][28][29]. These studies have used residual Açaí seeds in their natural state [17][18][19] or activated residual Açaí seeds [8,[20][21][22][23][24][25][26][27][28][29][30][31] and have involved chemical activation with NaOH [8,21,…”

“…In addition, temperature is one of the key factors influencing the thermochemical decomposition of biomass compounds during the production of bio-oil by pyrolysis. The bio-oil obtained by pyrolysis of Açaí seeds contains hydrocarbons and a oxygenate fraction rich in phenols [31,32], which are of great interest due to their potential applications as sources of antioxidants, nutraceuticals, and preservatives in the food industry [34]. In the food industry, phenolic compounds are recognized for their natural antioxidant properties.…”