Thermal Cracking Characteristics and Kinetics of Oil Sand Bitumen and Its SARA Fractions by TG-FTIR

The thermal cracking process of oil sand bitumen was investigated via studying the thermal cracking behaviors and online-gas-releasing characteristics of its SARA fractions (saturates, aromatics, resins, asphaltenes) by using TG-FTIR. The results showed that the asphaltenes contributed the most to coke formation of oil sad bitumen according to its largest weighted coke yield-compared with that of others. The online FTIR analysis for the gases evolved from the thermal cracking process of oil sand bitumen and its SARA fractions indicated that the gaseous products in the main reaction stage showed more complex composition than those in the volatilization stage, and predominantly consisted of CO2, CO, methane, ethylene, other light-alkalies and olefins, light aromatics, and hydrogen sulfide. Moreover, the release behaviors of typical gaseous products (CO2. CO, methane, ethylene, and light aromatics) for oil sand bitumen and its SARA fractions were different due to the different composition and Structure. The thermal-cracking kinetic parameters of oil sand bitumen and its SARA fractions were determined using the iso-conversional Friedman procedure at heating rates of 10 to 800 K/min. The activation energy of oil sand bitumen ranging from 93.74 to 215.99 kJ/mol in the whole thermal cracking process fell in between that of aromatics and resins. The variation of activation energy with the conversion rate for oil sand bitumen during the thermal cracking process was influenced by the interaction between SARA. fractions.