Conversion of sugarcane bagasse and polyethylene to bio-oil with hydro-solvo thermal liquefaction
Creators: name: BALOCH, Humair
Publisher: name: RMIT University
Year: 2024
Subjects: classificationCode: 400402
subject: Chemical and thermal processes in energy and combustion

description: The co-liquefaction of sugarcane bagasse and polyethylene is a promising method for producing high-quality bio-oil. This technology can also help with the recycling of plastic and organic waste in municipal solid waste. The aim of this research is to better understand the cross-reactions that occur during co-liquefaction between sugarcane bagasse and plastics, as well as to improve these reactions in order to maximize the yields of useful chemicals and hydrocarbons. <br><br>
The main interest to this research study is the production of bio-oil from lignocellulosic biomass and plastic waste and its upgrading process, viz.co-liquefaction of sugarcane bagasse and polyethylene is to improve the quality of bio-oil in laboratory scale studies using a Parr rector. This study also illustrates the interaction of sugarcane bagasse with polyethylene during co-liquefaction process and the role of the interaction in improving the quality and quantity of the product yield. Pyrolysis and liquefaction are widely accepted methods used for the synthesis of bio-oil using biomass. The quality and quantity of the bio-oil, produced either from pyrolysis or liquefaction, depend on various parameters including reaction temperature, reaction time, type of solvent and its ratio to biomass, lignocellulosic composition of feedstock and catalyst. Comparatively, hydrothermal liquefaction (HTL) is considered as more economic and environmentally friendly process than pyrolysis. Hydro/solvothermal liquefaction of sugarcane bagasse was carried out in ethanol and water as solvents at different temperatures, 240 °C, 260 °C and 280 °C. Higher conversion was obtained at the higher temperatures with ethanol. The bio-oil yield ranged from 46.0% to 51.8% in presence of water and from 54.6% to 62.3% with ethanol solvent by changing reaction temperature from 240 °C to 280 °C. The char yield decreased from 36.3% to 28.2% and from 39.3% to 24.7% in presence of water and ethanol respectively by varying reaction temperature from 240 °C to 280 °C. The carbon content and HHV were increased and oxygen content was decreased in the products thereby resulting in improved heating and combustion performance. The TGA results showed that the thermal stability of char was improved which is attributed to the reaction temperature of the liquefaction process. The co-liquefaction of mixtures of sugarcane bagasse and high- density polyethylene (HDPE) in ethanol under subcritical and super-critical conditions was studied with the objective of finding optimal process conditions for bio-oil yield and overall conversion. Taguchi method was employed to design with 9 experiments to find the effect of 4 independent variables (temperature, reaction time, biomass to plastic composition and solvent-to-biomass ratio) on the co-liquefaction of plastic and biomass for total conversion and bio-oil yield. The optimal results showed 60 % conversion with bio-oil yield 32.3 % having HHV of bio-oil 29.6 MJ/kg respectively. The predicted model indicated a good fit with that of experimental data. The co-liquefaction of sugarcane bagasse and polyethylene was found effective to improve the qualitative and quantitate features of products from the biomass. Catalytic co-liquefaction of high-density polyethylene and sugarcane bagasse over metal salt and oxide catalysts in ethanol solvent were investigated. The results of detailed characterization studies suggested that adding ZnSO4 gives the highest HHV (34.61 MJ/kg), while CuSO4 gives the highest bio-oil yield (38.42 %) and conversion (69.54 %). The liquid products are promising bio-fuel precursors for further utilization. Co-liquefaction of high-density polyethylene (HDPE) and sugarcane bagasse (SCB) was investigated in ethanol/water mixed solvent system. It was revealed that various ethanol/water mixing ratios will lead to various reaction mechanisms, which indicates that there is a clear synergy effect between water and ethanol liquefaction process in three reaction media. The conversion and bio-oil yield approach were in the order of pure water<br>

The bio-oil was upgraded in sub-supercritical ethanol using metal supported platinum on activated carbon (Pt/AC) and palladium on activated carbon (Pd/AC) as catalysts. The supercritical upgrading process revealed more effective process compared to the subcritical conditions. Esterification during catalytic upgrading of bio-oil remained prominent which facilitates the conversion of acids present in bio-oil into esters in sub-supercritical ethanol. In addition, heavy compounds of crude bio-oil cracked into lighter compounds in the presence of catalysts. Furthermore, the changes in the upgraded bio-oil relative to crude bio-oil was extensively investigated through higher heating value (HHV), elemental analysis, solution pH, chemical composition (GC-MS), chemical functional groups (FTIR), and 13C and 1H nuclear magnetic resonance spectroscopy (NMR). The chemical composition analysis showed a significant decrease in acid fractions in sub-supercritical upgrading process, which was reflected by increase in solution pH from 2.5 in bio-oil to 5.3 after the supercritical reaction. The HHV of bio-oil increased from 28.55 to 36.4 MJ/kg. This research has shown that crude bio-oil can be efficiently upgraded with carbon-supported metal catalysts in a sub-supercritical upgrading process.