Mixture of fossil hydrocarbons with palm oil for co-processing: a thermokinetic approach
摘要
This work focuses on the thermal and kinetic characterization of mixtures of petroleum intermediate distillates with palm oils, through the combined use of thermogravimetry (TGA) and advanced isoconversional analysis. The thermokinetic behavior of the hydrocarbon mixture, regardless of the presence of bio-oil, describes a simple vaporization process, with energy barriers < 100 kJ mol−1, linked to the energy required to overcome long-range cohesive intermolecular forces. Conversely, thermokinetic results for bio-oil in the hydrocarbon mixture occur in multi-step processes, with variable energy barriers between ~ 210 and ~ 340 kJ mol−1, typical of competitive processes. These results reflect the high degree of dispersion of the bio-oil and its low interaction with the components of the hydrocarbon mixture, which allows the chemical and thermophysical characteristics of both to be preserved, at least for the concentrations explored. The thermodynamic activation parameters show the endothermic (ΔH≠ > 0) and endergonic (ΔG≠ > 0) character and the minimal influence of the TΔS≠ term on the formation of the transition state. A constant and close to unity transformability index (Zα,T ≈ 0.91) validates the simple nature of the process for T < 453 K, the low influence of bio-oil in the hydrocarbon mixture, and the independent character of the physical phenomenon that controls the rate-limiting step of the process. The study shows the usefulness of thermogravimetric (TG) analysis and advanced isoconversional analysis to establish thermal stability limits, compatibility criteria and nature of interactions in liquid fuels or mixtures, critical factors for their co-processing, storage, transportation and utilization.