Preparation and characterization of microcrystalline wax from ShenbeiDaqing vacuum residue

To probe the possibility of producing microcrystalline wax with high melting point from Shenbei-Daqing vacuum residue, the residue was first deasphalted through a series of solvent deasphalting procedures with propane and butane to obtain deasphalted oil (DAO), and then the microcrystalline wax was prepared from DAO by solvent refining and dewaxing. The carbon number distribution, average molecular weight，composition and structure of microcrystalline wax were determined by GC, GPC, FT-IR and 1H-NMR. The melting points of microcrystalline wax samples meet the demands of 80# to 85# commercial products. The potential content of microcrystalline wax is about 10% in Shenbei-Daqing vacuum residue. The carbon number of the light microcrystalline wax ranges from 23 to 68. The number average molecular weight ranges from 1200 to 1600 and H/C atom ratio from 1.95 to 1.98. The microcrystalline wax is dominated by paraffins of long chains; of them about 70% are isoparaffins. There are a small amount of cycloalkanes and almost no aromatic hydrocarbons in the microcrystalline wax. The molecular structure of microcrystalline wax can be regarded as cycloalkanes with 1 or 2 rings and various long alkyl chains.