Pour Point Reduction of Waxy Crude Oil by Pyrolysis in Supercritical Methanol

The reduction of pour point of waxy crude oil by pyrolysis under high pressure N2 or supercritical methanol (scMeOH) environment was experimentally studied at the temperatures ranging from 370 to 400 degrees C. During the pyrolysis under N-2 environment, only a poor pour point reduction less than 5 degrees C, which is at the cost of the substantial condensation of saturates and aromatics to resins and asphaltenes, could be achieved. When the pyrolysis is transferred into the sc MeOH phase, the reaction consists primarily of the preferential cracking of wax fraction to gas. Benefiting from improved diffusivity, the cracking of wax fraction following the Fabuss-Satterfield-Smith mechanism is remarkably accelerated. Being the secondary reaction of the cracking of oil fractions at the moderate temperatures applied, the condensation of oil fractions is suppressed. Accordingly, an effective pour point reduction up to 22 degrees C could be obtained in 15 min of pyrolysis without sacrificing the quality of pyrolysis products.