Supercritical methanol as an effective medium for producing asphaltenes-free light fraction oil from vacuum residue

Abstract

The upgrading of vacuum residue (VR) in supercritical methanol (scMeOH) was investigated without using catalysts. Various process parameters, including temperature (350–425°C), reaction time (30–90min), and additives (toluene and hydrogen) were explored to optimize the yield of light fraction oil (LFO) with few impurities. At a 400°C, 16.7wt% of VR in methanol for 60min, the LFO produced in scMeOH contained very low asphaltene content (0.74wt%) and a very low amount of heteroatom/metallic impurities (S, 3.58wt%;N, non-detectable; Ni, 10.4ppm;V, 36.9ppm, Fe, 7.3ppm). In addition, the naptha-to-diesel fraction increased from 1wt% (VR feed) to 15wt% and the saturate+aromatic content increased from 43.7 area% (VR feed) to 59.6 area% in the LFO. When the reaction time was extended to 90min at 400°C, a complete removal of asphaltenes could be achieved.