Study on the Isolated Asphaltene Thermal Cracking from an Unconventional Oil Using Diverse Estimating Arrhenius Parameter Approaches.

The lack of complex schemes and proper kinetic studies for asphaltenes pyrolysis is a significant problem for understanding the reaction mechanisms. Therefore, this study evaluates various parameter estimation approaches (focusing on reaction rate coefficients and Arrhenius parameters), objective functions (sum of squared errors and average absolute errors), and reaction schemes (4-lump and 6-lump) for kinetic modeling of asphaltene pyrolysis. The reaction schemes include asphaltenes, maltenes, gases, and coke, as well as the fractionation of maltenes into polar aromatics, naphthene aromatics, and saturates. Both networks showed adequate accuracy, but the 6-lump model improves yield predictions. Using Method 1 (optimizing reaction rate coefficients) and the sum of square errors as the objective function yields the best accuracy. The analyses confirm that temperature influences selectivity: lower temperatures (below 390 °C) favor the generation of maltenes and gases, while higher temperatures (above 390 °C) promote coke formation. Extended high-temperature exposure leads to secondary cracking of maltenes. Furthermore, the key transformations include the cleavage of aliphatic chains, the aromatization of saturated aromatics, and the polyaddition of free radicals.