A molecular insight into cracking of the asphaltene hydrocarbons by using microwave radiation in the presence of the nanoparticles acting as catalyst

Abstract

This research aims to the microwave-assisted catalytic cracking of the asphaltene by using nanoparticles of SiO2, Al2O3, clay, and ZnO acting as a nanocatalyst. The nanoparticle-added oil samples were treated by microwave radiation at the radiation power of 1200 W for 10 min. After extracting the asphaltene, Nuclear Magnetic Resonance (NMR), Fourier Transformed Infrared (FTIR), elemental analysis, Energy-dispersive X-ray (EDX) spectroscopies, and Inductively Coupled Plasma Atomic Emission (ICP-OES) were implemented to characterize the treated asphaltene. Based on the characteristic results, aromatic fused rings have been slightly cracked due to the microwave radiation in the presence of the ZnO and Al2O3 nanoparticles. Besides, the average carbon number of the associated aliphatic chains was reduced to the range of 3.3–3.9 from 5.4 after the microwave radiation. In addition, the microwave radiation in the presence of the nanoparticles reduces the Vanadium and Nickel concentrations of the asphaltenes to 71–90% and 75–93% of the ones in the crude asphaltene, respectively. Based on the indexes, calculated from FTIR spectrums, the asphaltenes are adsorbed on the nanoparticles, leading to absorbing higher microwave energy. By adsorbing the polar functional groups of asphaltene on the nanoparticle, they are heated until the bond cracking, leading to asphaltene release. An analogical insight to the viscometric tests and asphaltene molecular structure showed that the reduction of the electrostatic forces and the Hydrogen interactions are the main reason for the lower tendency of treated asphaltene to aggregate. Based on this study, fine particles, co-producing with crude oil, could catalyze the asphaltene cracking during microwave radiation.