Catalytic co-pyrolysis of Vachellia Farnesiana with polypropylene plastic to produce bio-oil: Parameter optimization study

Abstract

Catalytic co-pyrolysis of biomass Vachellia Farnesiana (VF) and Polyropylene (PP) plastic was carried out using sodium carbonate (Na2CO3) catalyst to produce high quality oil. A semi batch pyrolysis reactor was used to perform the co-pyrolysis of VF and PP at different temperatures (350–550 °C), time (20-60mins), VF/PP ratio (0–100 %) and catalyst loading (0–10 %). The experiments were conducted using 40 g feed mixture to optimize the feed ratio, temperature, reaction time, and Na2CO3 catalyst ratio. The best conditions for the process were thus found to be 450 °C temperature, 40 min time, and 5 wt% Na2CO3 catalyst. Under these conditions, the maximum fuel oil yield of ∼ 64 % was achieved, which was approximately 4 % higher than oil yield obtained without utilization of Na2CO3 catalyst. Variations in temperature, the VF/PP ratio, and the Na2CO3 catalyst parameters had the most significant effects on improving the quality of the oil. The utilization of Na2CO3, along with an increase in temperature and the amount of PP in the VF/PP blend, contributed to higher yields and a greater gross calorific value (GCV) of the obtained oil. FTIR analysis was conducted to identify the functional groups present in the oil. Similarly, GCMS analysis further revealed that the presence of a significant alkanes and alkenes, along with fewer oxygenates, was responsible for the favorable GCV of the oil. The addition of the Na2CO3 catalyst was found to increase the concentrations of alkanes, alkenes, and alcohols, while reducing acids, ethers, and ketones. As a result, it was able to enhance the quality of the oil.