Modification of Vacuum Residue by Heat Treatment Aided by Hydrogen Donor to Obtain Needle Coke through Cocarbonization with FCC-DO.

Pyrolytic depolymerization of asphaltene fraction in petroleum low sulfur vacuum residue (LSVR) was achieved at 480-500℃C with the aid of a hydrogen donor, tetrahydrofluoranthene (4HFL). Such depolymerization was effective for removing the bottom mosaic texture in the lump needle coke of excellent low coefficient of thermal expansion (CTE) produced through the cocarbonization of modified LSVR with fluid catalytic cracking decant oil (FCC-DO) of rather paraffinic structure in a tube bomb. The role of the hydrogen donor in such pyrolysis is discussed to clarify the scheme for reducing the molecular weight of the heaviest portion in the asphaltene without the formation of a benzene-insoluble coke precursor. The dealkylation accelerated with the donor may fission the methylene bonds which connect the aromatic nuclei in the asphaltene, increasing the aromaticity and enhancing the thermal stability of the heat-treated asphaltene.