Treatment Of Petroleum Asphalt By Direct Liquefaction Residue Based On Aldehyde Crosslinking Agent

Asphalt is widely used around the world in road pavement attribute to its good viscoelastic properties. Unfortunately, futher applications of asphalt are restricted by some disadvantages of itself and the increasing volume of traffic. So the matrix asphalt need to modify to improve its performance. Previous research indicated that direct coal liquefaction residue(DCLR) has a similarity physical properties and composition with the TLA, so it may can replace the natural lake asphalt to prepare modified asphalt at a significantly less consumption than TLA. This not only can lower the cost of modified asphalt, but also can relieve environmental problems caused by liquefaction residues and increase economical efficiency of coal oil products. Whereas considering the tetrahydrofuran insoluble fraction of direct coal liquefaction residue will lead to the ductility of modified asphalt reduce, therefore we select tetrahydrofuran soluble fraction of direct coal liquefaction residue(THFS) as asphalt modifier. Crosslinking agent of Aldehydes including:formaldehyde, trioxymethylene and benzaldehyde. The aldehyde group of the formaldehyde can open the aromatic rings serving as bifunctional groups that connect the asphalt and THFS to produce low polymers with multiple aryl methanes.The asphalt was modified by tetrahydrofuran soluble fraction of direct coal liquefaction residue. Modification conditions such as mixing temperature, ratio of THFS and crosslinking agent to asphalt were studied. The optimal conditions were as follows:mixing temperature of 170 ℃, and THFS to asphalt ratio of 4 wt.%. The modified asphalt can get same property with low blending ratio of THFS by using crosslinking agent.Characterisations of modified asphalt and DCLR were performed by means of TG-FTIR, FTIR and fluorescence microscope. The results show that the residue in N2 atmosphere have shown two pyrolytic section, and the heating rate and content of heavy components both have effects on residue pyrolysis. Comparing with other asphalt the weight loss of modified asphalt which added crosslinking agent was lower. The modified asphalt with crosslinking agent has less CH4 release than other samples and CH4 was released at higher temperature. The involvement of crosslinking agent increased the stretching vibration of aliphatics (-CH2-) of modified asphalt at 2924 cm-1 and 2854 cm-1 as well as the transmittance of the absorption peaks at 872 cm-1,810 cm-1 and 746 cm-1 representing benzene substituent significantly, and at 1060 cm-1 it appeared new absorption peak which represented C-O-C stretching vibration. Moreover the new modified particles in the fluorescence microscope images indicated that the involvement of cross-linking agent may cause polycondensation of THFS and the matrix asphalt. Based on asphalt modification experiment by the four components of DCLR respectively can found that heavy oil can significantly enhance the ductility and penetration of the modified asphalt, as well as reduce softening point. While the asphaltenes and pre-asphaltenes can make the softening point of modified asphalt increased, meanwhile the penetration decreased.