The effect of temperature on the molecular structure of Raman asphaltenes during pyrolysis

► Asphaltenes were precipitated from Raman heavy crude oil subjected to pyrolysis. ► Molecular structure of unreacted asphaltenes were characterized. ► The breaking off alkyl chains from the asphaltene and aromatization in the asphaltene during the pyrolysis of asphaltene occurred especially at 400 and 450 °C with increasing time.