Thermal cracking of asphaltene by addition of hydrogen donor solvent.

摘要

Better definition of asphaltene structure is needed to develop new technology for upgrading, and to understand various bitumen properties. Analysis of asphaltene structure is hampered by aggregation of molecules at a length scale of 5 to 10 nm. At 300°C, the addition of aromatic solvents can partly, but not completely suppress aggregation of asphaltenes. This study will investigate a new method, thermal cracking combined with presoaking of a mixture of asphaltene and hydrogen donor solvent to suppress the aggregation and to maximize yield of cracked fragments.;Asphaltene thermal cracking was carried out in micro batch reactor at 430°C by fluidized sand bath for 1 hour. Compared with non-solvent addition in thermal cracking, mixing of tetralin and tetrahydroquinoline with asphaltene greatly reduced the coke yield from 38% to 2%. To further enhance the solvent’s hydrogen transfer ability and the disaggregation of asphaltene, a presoaking stage at 200°C was performed prior to thermal cracking. In addition, parallel tests between tetralin and tetrahydroquinoline were conducted at different time periods ranging from 30 minutes up to 3 hours. Effects of nitrogen and oxygen reaction environment were also studied for the presoaking case to check for their effects. Compared with the case of direct solvent addition during thermal cracking, presoaking of either tetralin or tetrahydroquinoline with asphaltene did not show any significant reduction in coke yield for different presoaking periods, gas environment, or cooling interval.