Enhanced biofuel production from Sacha Inchi wastes: Optimizing pyrolysis for higher yield and improved fuel properties

Abstract

Sacha inchi waste consists of residues (SR) and shells (SS) that are processed into liquid fuel using a traditional pyrolysis process. Pyrolysis was performed at a constant heating rate of 20 °C/min and nitrogen flow rate of 100 mL/min. Before the process took place, a preliminary TGA analysis was performed and the results revealed that the appropriate pyrolysis temperature and time allowed a variation of 250–450 °C and 10–50 min, respectively. The results showed that the pyrolysis oil yields of both SR and SS increased with increasing pyrolysis temperature and time. However, the pyrolysis oil yield of SR was significantly higher than that of SS because the main component of SR contains abundant carbon from saturated fatty acids. The ANOVA method shows that the SS model is more complex and examines more terms and interactions, whereas the SR model is simpler and focuses on fewer components, but still shows significant effects, especially through temperature. The nonsignificant p-value for time in the SR model suggests that time may not have the same influence as temperature on the dependent variable. The SS pyrolysis oil was consistent and resulted in a constant calorific value and flash point between 31.10 and 32.14 MJ/kg and 120 and 124 °C, respectively. However, decreasing the O/C atomic ratio of SR pyrolysis oil from 0.92 to 0.38 influenced the increasing calorific value from 36.66 to 38.75 MJ/kg, while the H/C atomic ratio of SR pyrolysis oil was close to 2.00. This suggests that its effectiveness maintains an alkene structure that can improve fuel efficiency. The molecular formulae of the SS pyrolysis oil were CH16N0.04O7 and that of SR pyrolysis oil was CH2.2N0.08O0.45.